Статті в журналах з теми "Bionic hand prosthesis"

Finger joint angle pattern recognition is significant for the development of an intelligent bionic hand. It makes the intelligent prosthesis understand the users intension more accurately and complete movements better. Surface electromyography signals have been widely used in intelligent bionics prosthesis research and rehabilitation medicine due to its advantages like high efficiency, convenient collection and non-invasive access. An improved grid-search method using a support vector machine has been proposed for the finger joint angle pattern recognition issue in surface electromyography signals. Pattern recognition for surface electromyography signals of index finger movement and metacarpophalangeal joint angle has been performed. Better classification performance was achieved through screening of feature vector combined with an improved grid-search support vector machine classification algorithm.

We describe use of a bidirectional neuromyoelectric prosthetic hand that conveys biomimetic sensory feedback. Electromyographic recordings from residual arm muscles were decoded to provide independent and proportional control of a six-DOF prosthetic hand and wrist—the DEKA LUKE arm. Activation of contact sensors on the prosthesis resulted in intraneural microstimulation of residual sensory nerve fibers through chronically implanted Utah Slanted Electrode Arrays, thereby evoking tactile percepts on the phantom hand. With sensory feedback enabled, the participant exhibited greater precision in grip force and was better able to handle fragile objects. With active exploration, the participant was also able to distinguish between small and large objects and between soft and hard ones. When the sensory feedback was biomimetic—designed to mimic natural sensory signals—the participant was able to identify the objects significantly faster than with the use of traditional encoding algorithms that depended on only the present stimulus intensity. Thus, artificial touch can be sculpted by patterning the sensory feedback, and biologically inspired patterns elicit more interpretable and useful percepts.

The Mechanical and Technological Innovation Centre (CDMIT) of the National Autonomous University of Mexico has a research area focused on the design of upper limb prosthesis. A large number of prosthesis have been developed and tested. This paper presents the analysis made to different proposals of myoelectric hands based on TRIZ. Two TRIZ tools were applied: The Innovation Situation Questionnaire (ISQ) and the Radar of Evolution. The analysis was made in terms of time, space and the user interface. The ISQ helps to better define the scope of the problem through six basic questions; each question provides a different view of the problem. The radar of evolution helps to make a selection of trends of evolution depending on the product or system, as an analogy of a benchmark. The analysis was made considering the state-of-the-art hand prosthesis: i-limb, be-bionic, Michelangelo and Myohand against the prosthesis prototypes developed by the CDMIT. The result of this tool is a diagram that reveals the level and opportunities of evolution. These opportunities imply a strengthening of research areas not only in the CDMIT but around the world. The conclusion achieved is that different design paradigms linked to bio-mimics criteria are needed to design more innovative user-friendly prosthesis.

Current myoelectric prostheses allow transradial amputees to regain voluntary motor control of their artificial limb by exploiting residual muscle function in the forearm. However, the overreliance on visual cues resulting from a lack of sensory feedback is a common complaint. Recently, several groups have provided tactile feedback in upper limb amputees using implanted electrodes, surface nerve stimulation, or sensory substitution. These approaches have led to improved function and prosthesis embodiment. Nevertheless, the provided information remains limited to a subset of the rich sensory cues available to healthy individuals. More specifically, proprioception, the sense of limb position and movement, is predominantly absent from current systems. Here, we show that sensory substitution based on intraneural stimulation can deliver position feedback in real time and in conjunction with somatotopic tactile feedback. This approach allowed two transradial amputees to regain high and close-to-natural remapped proprioceptive acuity, with a median joint angle reproduction precision of 9.1° and a median threshold to detection of passive movements of 9.5°, which was comparable with results obtained in healthy participants. The simultaneous delivery of position information and somatotopic tactile feedback allowed both amputees to discriminate the size and compliance of four objects with high levels of performance (75.5%). These results demonstrate that tactile information delivered via somatotopic neural stimulation and position information delivered via sensory substitution can be exploited simultaneously and efficiently by transradial amputees. This study paves a way to more sophisticated bidirectional bionic limbs conveying richer, multimodal sensations.

Despite previous studies on the restoration of tactile sensation to the fingers and the hand, there are no examples of use of the routed sensory information to finely control a prosthestic hand in complex grasp and manipulation tasks. Here, it is shown that force and slippage sensations can be elicited in an amputee by means of biologically inspired slippage detection and encoding algorithms, supported by a stick-slip model of the performed grasp. A combination of cuff and intraneural electrodes was implanted for 11 weeks in a young woman with hand amputation and was shown to provide close-to-natural force and slippage sensations, paramount for substantially improving manipulative skills with the prosthesis. Evidence is provided about the improvement of the participant’s grasping and manipulation capabilities over time resulting from neural feedback. The elicited tactile sensations enabled the successful fulfillment of fine grasp and manipulation tasks with increasing complexity. Grasp performance was quantitatively assessed by means of instrumented objects and a purposely developed metrics. Closed-loop control capabilities enabled by the neural feedback were compared with those achieved without feedback. Further, the work demonstrates that the described amelioration of motor performance in dexterous tasks had as central neurophysiological correlates changes in motor cortical plasticity and that such changes were not of purely motor origin, but were the effect of a strong and persistent drive of the sensory feedback.

This research concerns the design of a three-jointed, anthropomorphic, finger mechanism for use as a prosthesis or robotic end-effector. Based on a study of finger configurations for the human hand, a six-bar linkage with one degree of freedom is proposed. A model of the fingertip displacement of the mechanism is derived by a vector analysis approach. The effects of joint friction on the transmission efficiency are analysed. By measuring the joint positions of a human finger, a mathematical model of the pinching and holding configurations are developed. Optimal parameters for the finger mechanism are obtained by non-linear programming based on an objective functional involving motion posture and locus, transmission efficiency and weight subject to geometric and bionic constraints. Simulation results indicate that the mechanism is useful for a variety of prosthetic and robotic applications.

Electromyographic prosthesis with higher degrees of freedom is an expanding area of research. In this paper, active prosthesis with four degrees of freedom has been investigated, which can be used to fit a limb with amputation below elbow. The system comprises of multichannel inputs which correspond to the flexion and extension as well as supination and pronation. To find maximum surface neural activity, accurate placement of electrodes has been carried out on 10 subjects aged between 22-30 years. Signals (0-500 hertz) acquired from contracting voluntary muscles with minimum cross talk and common mode noise. Clean filtered EMG signal is then amplified precisely. Finally digitization is being done to drive bionic hand. Practical demonstration on a simple DC motor proved providential using this method for the two motions of an actual human arm. EMG Signals emanating from muscles dedicated to individual fingers have been recorded. Moreover modern classifiers; KNN and NN have been investigated carefully with selected features through different time and noise levels.

With the development of robotics, intelligent neuroprosthesis for amputees is more concerned. Research of robot controlling based on electrocardiogram, electromyography, and electroencephalogram is a hot spot. In medical research, electrode arrays are commonly used as sensors for surface electromyograms. Although these sensors collect more accurate data and sampling at higher frequencies, they have no advantage in terms of portability and ease of use. In recent years, there are also some small surface electromyography sensors for research. The portability of the sensor and the calculation speed of the calculation method directly affect the development of the bionic prosthesis. A consumer-grade surface electromyography device is selected as surface electromyography sensor in this study. We first proposed a data structure to convert raw surface electromyography signals from an array structure into a matrix structure (we called it surface electromyography graph). Then, a convolutional neural network was used to classify it. Discrete surface electromyography signals recorded from three persons 14 gestures (widely used in other research to evaluate the performance of classifier) have been applied to train the classifier and we get an accuracy of 97.27%. The impacts of different components used in convolutional neural network were tested with this data, and subsequently, the best results were selected to build the classifier used in this article. The NinaPro database 5 (one of the biggest surface electromyography data sets) was also used to evaluate our method, which comprises of hand movement data of 10 intact subjects with two myo armbands as sensors, and the classification accuracy increased by 13.76% on average when using double myo armbands and increased by 18.92% on average when using single myo armband. In order to driving the robot hand (bionic manipulator), a group of continuous surface electromyography signals was recorded to train the classifier, and an accuracy of 91.72% was acquired. We also used the same method to collect a set of surface electromyography data from a disabled with hand lost, then classified it using the abovementioned network and achieved an accuracy of 89.37%. Finally, the classifier was deployed to the microcontroller to drive the bionic manipulator, and the full video URL is given in the conclusion, with both the healthy man and the disabled tested with the bionic manipulator. The abovementioned results suggest that this method will help to facilitate the development and application of surface electromyography neuroprosthesis.

Subject. The article analyzes development trends in certain types of service robots, namely, hybrid UAVs, bionic prosthetic hands, robotic vacuum cleaners. Objectives. We focus on identifying the main trends in the development of certain types of service robots, building dynamic models of their technical indicators and models of dependence of their price and weight on absolute characteristics and technical parameters. Methods. The study employs methods of correlation and multiple regression analysis. The data of the IFR, the Remotely Piloted Aircraft System, and websites of robot manufacturers serve as the informational basis of the paper. Results. The modeling unveils positive correlation between the integrated indicator of the technical level of hybrid UAVs of convertiplane type and the wingspan. The analysis of modern bionic prosthetic hands shows that the developers focus on optimizing the structure of the prosthetic, however, as the functions of the hand improve, the weight of bionic hand increases. The main factors influencing the price of robot vacuum cleaners are their power, weight, and operating hours. Conclusions. The unit price of a complex indicator of the technical level of hybrid UAVs is lower than the corresponding indicator of fixed-wing UAVs, reflecting a greater efficiency of hybrid UAVs. The analysis of technical indicators of robotic prosthetics (using the case of bionic hands) shows that any improvement of functional characteristics leads to deterioration of weight. The analysis of technical and economic indicators of robotic vacuum cleaners reveals a positive correlation between the price and weight, operating hours and power.

The complexity of the user interfaces and the operating modes present in numerous assistive devices, such as intelligent prostheses, influence patients to shed them from their daily living activities. A methodology to evaluate how diverse aspects impact the workload evoked when using an upper-limb bionic prosthesis for unilateral transradial amputees is proposed and thus able to determine how user-friendly an interface is. The evaluation process consists of adapting the same 3D-printed terminal device to the different user-prosthesis-interface schemes to facilitate running the tests and avoid any possible bias. Moreover, a study comparing the results gathered by both limb-impaired and healthy subjects was carried out to contrast the subjective opinions of both types of volunteers and determines if their reactions have a significant discrepancy, as done in several other studies.

One aspect that needs to be assessed to make better product is usability. Testing the level of usability on BIMO hand is performed using adapted Southampton Hand Assesment Procedure (SHAP) method. Users are given the task of using prosthetic hand to perform daily activities according to performance measurement rules. Based on the opinion of Jacob Nielsen, the theory used to measure usability are 5 main parameters, i.e: Learnability, Memorability, Efficiency, Satisfaction, and Errors. Testing is done by giving 15 task daily activity to the respondent. After testing, respondents were given USE questionnaires (Usefulness, Satisfaction and Ease of use) as a media for usability assessmentand received suggestions from respondents. Some suggestions were obtained from the respondents after the research was conducted, such as the size of the product, censoric product respond, the suitability shape and weight of product. Based on the percentage of USE questionnaire assessment known Usability Prosthetic hand level tested is in the status of GOOD, this indicates the respondents feel the product is good to use.

We are living in an era in which technology is shaping the world at an incredible speed. In this wake, the Bionics laboratory of the Department of Mechanical Engineering of the University of Moratuwa is doing inspiring research to improve the quality of life of differently-abled people. The latest product of this effort emerged as the iGrasp Hand, a robotic prosthetic hand that can mimic the grasping patterns of a human hand.

Background: Bilateral metacarpal hand injuries are extremely rare, but probably represent the most difficult reconstructive challenge in hand surgery. Methods: We discuss the various options for metacarpal hand reconstruction, including the Krukenberg procedure, bionic prostheses, multiple toe-to-hand transfers, and possibly hand transplantation, and present the long-term functional outcomes, gait analysis, and psychological evaluation after a 4-stage reconstruction of bilateral metacarpal hands in a child using 6 toe-to-hand transfers—bilateral great toe transfers to reconstruct both thumbs and bilateral combined second-third monobloc transfers to reconstruct 2 fingers in each hand. Results: Reconstruction of bilateral metacarpal hands with 6 toe transfers yielded excellent functional results and patient satisfaction. Conclusions: Bilateral metacarpal hand injuries result in a devastating functional deficit and a major psychological impact. Multiple toe transfers (4, 5, or 6) provide an excellent reconstructive outcome with acceptable donor site morbidity.

Bionic hands have been employed in a wide range of applications, including prosthetics, robotic grasping, and human–robot interaction. However, considering the underactuated and nonlinear characteristics, as well as the mechanical structure’s backlash, achieving natural and intuitive teleoperation control of an underactuated bionic hand remains a critical issue. In this paper, the teleoperation control of an underactuated bionic hand using wearable and vision-tracking system-based methods is investigated. Firstly, the nonlinear behaviour of the bionic hand is observed and the kinematics model is formulated. Then, the wearable-glove-based and the vision-tracking-based teleoperation control frameworks are implemented, respectively. Furthermore, experiments are conducted to demonstrate the feasibility and performance of these two methods in terms of accuracy in both static and dynamic scenarios. Finally, a user study and demonstration experiments are conducted to verify the performance of these two approaches in grasp tasks. Both developed systems proved to be exploitable in both powered and precise grasp tasks using the underactuated bionic hand, with a success rate of 98.6% and 96.5%, respectively. The glove-based method turned out to be more accurate and better performing than the vision-based one, but also less comfortable, requiring greater effort by the user. By further incorporating a robot manipulator, the system can be utilised to perform grasp, delivery, or handover tasks in daily, risky, and infectious scenarios.

OBJECTIVEGlobal brachial plexus lesions with multiple root avulsions are among the most severe nerve injuries, leading to lifelong disability. Fortunately, in most cases primary and secondary reconstructions provide a stable shoulder and restore sufficient arm function. Restoration of biological hand function, however, remains a reconstructive goal that is difficult to reach. The recently introduced concept of bionic reconstruction overcomes biological limitations of classic reconstructive surgery to restore hand function by combining selective nerve and muscle transfers with elective amputation of the functionless hand and its replacement with a prosthetic device. The authors present their treatment algorithm for bionic hand reconstruction and report on the management and long-term functional outcomes of patients with global brachial plexopathies who have undergone this innovative treatment.METHODSThirty-four patients with posttraumatic global brachial plexopathies leading to loss of hand function consulted the Center for Advanced Restoration of Extremity Function between 2011 and 2015. Of these patients, 16 (47%) qualified for bionic reconstruction due to lack of treatment alternatives. The treatment algorithm included progressive steps with the intent of improving the biotechnological interface to allow optimal prosthetic hand replacement. In 5 patients, final functional outcome measurements were obtained with the Action Arm Research Test (ARAT), the Southampton Hand Assessment Procedure (SHAP), and the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire.RESULTSIn all 5 patients who completed functional assessments, partial hand function was restored with bionic reconstruction. ARAT scores improved from 3.4 ± 4.3 to 25.4 ± 12.7 (p = 0.043; mean ± SD) and SHAP scores improved from 10.0 ± 1.6 to 55 ± 19.7 (p = 0.042). DASH scores decreased from 57.9 ± 20.6 to 32 ± 28.6 (p = 0.042), indicating decreased disability.CONCLUSIONSThe authors present an algorithm for bionic reconstruction leading to useful hand function in patients who lack biological treatment alternatives for a stiff, functionless, and insensate hand resulting from global brachial plexopathies.

Global brachial plexopathies including multiple nerve root avulsions may result in complete upper limb paralysis despite surgical treatment. Bionic reconstruction, which includes the elective amputation of the functionless hand and its replacement with a mechatronic device, has been described for the transradial level. Here, we present for the first time that patients with global brachial plexus avulsion injuries and lack of biological shoulder and elbow function benefit from above-elbow amputation and prosthetic rehabilitation. Between 2012 and 2017, forty-five patients with global brachial plexus injuries approached our centre, of which nineteen (42.2%) were treated with bionic reconstruction. While fourteen patients were amputated at the transradial level, the entire upper limb was replaced with a prosthetic arm in a total of five patients. Global upper extremity function before and after bionic arm substitution was assessed using two objective hand function tests, the action research arm test (ARAT), and the Southampton hand assessment procedure (SHAP). Other outcome measures included the DASH questionnaire, VAS to assess deafferentation pain and the SF-36 health survey to evaluate changes in quality of life. Using a hybrid prosthetic arm mean ARAT scores improved from 0.6 ± 1.3 to 11.0 ± 6.7 (p = 0.042) and mean SHAP scores increased from 4.0 ± 3.7 to 13.8 ± 9.2 (p = 0.058). After prosthetic arm replacement mean DASH scores improved from 52.5 ± 9.4 to 31.2 ± 9.8 (p = 0.003). Deafferentation pain decreased from mean VAS 8.5 ± 1.0 to 6.7 ± 2.1 (p = 0.055), while the physical and mental component summary scale as part of the SF-36 health survey improved from 32.9 ± 6.4 to 40.4 ± 9.4 (p = 0.058) and 43.6 ± 8.9 to 57.3 ± 5.5 (p = 0.021), respectively. Bionic reconstruction can restore simple but robust arm and hand function in longstanding brachial plexus patients with lack of treatment alternatives.

The development of robotic hand prosthetic aims to give back people with disabilities, the ability to recover the functionality needed to manipulate the objects of their daily environment. The electrical signals sent by the brain through the nervous system are associated with the type of movement that the limbs must execute. Myoelectric sensors are non-intrusive devices that allow the capture of electrical signals from the peripheral nervous system. The relationship between the signals originated in the brain tending to generate an action and the myoelectric ones as a result of them, are weakly correlated. For this reason, it is necessary to study their interaction in order to develop the algorithms that allow recognizing orders and transform them into commands that activate the corresponding movements of the prosthesis.The present work shows the development of a prosthesis based on the design of an artificial hand Open Bionics to produce the movements, the MyoWare Muscle sensor for the capture of myoelectric signals (EMG) and the algorithm that allows to identify orders associated with three types of movement. Arduino Nano module performs the acquisition and control processes to meet the size and consumption requirements of this application.

The loss of mobility function and sensory information from the arm, hand, and fingertips hampers the activities of daily living (ADL) of patients. A modern bionic prosthetic hand can compensate for the lost functions and realize multiple degree of freedom (DoF) movements. However, the commercially available prosthetic hands usually have limited DoFs due to limited sensors and lack of stable classification algorithms. This study aimed to propose a controller for finger joint angle estimation by surface electromyography (sEMG). The sEMG data used for training were gathered with the Myo armband, which is a commercial EMG sensor. Two features in the time domain were extracted and fed into a nonlinear autoregressive model with exogenous inputs (NARX). The NARX model was trained with pre-selected parameters using the Levenberg–Marquardt algorithm. Comparing with the targets, the regression correlation coefficient (R) of the model outputs was more than 0.982 over all test subjects, and the mean square error was less than 10.02 for a signal range in arbitrary units equal to [0, 255]. The study also demonstrated that the proposed model could be used in daily life movements with good accuracy and generalization abilities.

AbstractIntroduction:Severe hand trauma, leading to extensive skeletal and tissue defects, requires plastic surgical reconstruction of the highest level aiming at maximizing function and aesthetics. The intention of this study was to investigate clinical parameters and resource consumption connected with severe hand injuries, with specific emphasis on a follow-up evaluation of quality of life after the reconstruction process.Materials and methods:In this retrospective study, we evaluated patients with severe hand injuries from 2013 to 2016 who had completed surgical and non-surgical treatment. Measures included total period of therapy (TPT) in days, total duration of operations including anesthesia (TOA), total duration of all operations (TO), and total number of operations (TNO). We also determined total inpatient stay (TIS), total number of clinic presentations with interventions (TNPI), initial hand injury severity score (iHISS), and inpatient proceeds (IPP) in Euros (€). Correlation was assessed between iHISS and TOA, TNO, and TIS. Finally, these patients were reexamined in a follow-up inquiry and the life quality was assessed with the five-level version of the EuroQol five-dimensional (EQ-5D) descriptive system (EQ-5D-5L).Results:We analyzed 12 patients with an average age of 44 years (min. 24 years, max. 75 years). Patients receiving reconstructive surgery experienced median (${\rm{\tilde x}}$) TPT of 175 days [interquartile range (IQR), 51–499], TOA of 13 h (IQR, 6–37), TO of 9 h (IQR, 4–25), and TNO of 5 (IQR, 3–11). Further, the patients’ median TIS was 22 days (IQR, 9–86), TNPI was 4 (IQR, 2–8), and iHISS was 77 (IQR, 44–162). The median IPP was 14.595 € (IQR, 5.541–33.709 €). IHISS was positively correlated with Pearson’s r for TIS (0.817), TOA (0.857), and TNO (0.871). The EQ-5D-5L index value resulted in a high level of life quality with a median of 0.898 (min. 0.8, max. 1).Conclusion:Severe hand injuries are related to high efforts for surgical and functional reconstructions, which result in high quality of life measured with the EQ-5D-5L assessment. However, for a defined collective of patients, myoelectric prosthetic functional replacement should be considered. Further studies are necessary to examine functional outcomes and quality of life after bionic prosthetic replacement. Also, a bionic reconstruction score to define hard criteria for taking an acute treatment decision is necessary.

AbstractThis paper aims to develop and validate a subject-specific framework for modelling the human hand. This was achieved by combining medical image-based finite element modelling, individualized muscle force and kinematic measurements. Firstly, a subject-specific human hand finite element (FE) model was developed. The geometries of the phalanges, carpal bones, wrist bones, ligaments, tendons, subcutaneous tissue and skin were all included. The material properties were derived from in-vivo and in-vitro experiment results available in the literature. The boundary and loading conditions were defined based on the kinematic data and muscle forces of a specific subject captured from the in-vivo grasping tests. The predicted contact pressure and contact area were in good agreement with the in-vivo test results of the same subject, with the relative errors for the contact pressures all being below 20%. Finally, sensitivity analysis was performed to investigate the effects of important modelling parameters on the predictions. The results showed that contact pressure and area were sensitive to the material properties and muscle forces. This FE human hand model can be used to make a detailed and quantitative evaluation into biomechanical and neurophysiological aspects of human hand contact during daily perception and manipulation. The findings can be applied to the design of the bionic hands or neuro-prosthetics in the future.

In this paper, we develop a prosthetic bionic hand system to realize adaptive gripping with two closed-loop control loops by using a linear discriminant analysis algorithm (LDA). The prosthetic hand contains five fingers and each finger is driven by a linear servo motor. When grasping objects, four fingers except the thumb would adjust automatically and bend with an appropriate gesture, while the thumb is stretched and bent by the linear servo motor. Since the change of the surface electromechanical signal (sEMG) occurs before human movement, the recognition of sEMG signal with LDA algorithm can help to obtain people’s action intention in advance, and then timely send control instructions to assist people to grasp. For activity intention recognition, we extract three features, Variance (VAR), Root Mean Square (RMS) and Minimum (MIN) for recognition. As the results show, it can achieve an average accuracy of 96.59%. This helps our system perform well for disabilities to grasp objects of different sizes and shapes adaptively. Finally, a test of the people with disabilities grasping 15 objects of different sizes and shapes was carried out and achieved good experimental results.

This article provides details of various smart prosthetics that have been developed in last few years. Behind smart prosthetics are many technologies powering consumer products-faster microprocessors, more powerful batteries, wireless technology and new control systems that use the body’s nerves and muscles. A new bionic hand enables users to move the thumb and index finger independently of the remaining three fingers, a significant advance in dexterity over prior claw-like mechanisms. The bionic ear transmits sound and power wirelessly to electrodes implanted deep in the ear, allowing the deaf to hear. The Rheo Knee uses force and position sensors that monitor speed and load more than 1000 times per second. This information goes to an artificial intelligence program that emulates the feedback a natural knee would receive from the body’s central nervous system. However, researchers believe that despite outstanding progress, the future holds more challenges; a second looming issue involves sensory input. At Brown University, neuroscience professor John Donaghue has teamed with Peckham to develop ways to activate nerves from within the brain itself. Their goal is to develop within five years a brain-controlled system that will let a tetraplegic take a glass of water, lift it, and bring it to his or her mouth.

To realize the adaptive grasping of objects with diverse shapes and to capture the joint angles of the finger, a multi degree of freedom (DOF) adaptive finger for prosthetic hand is proposed in this paper. The fingers are designed with three joints. The maximum rotation angle of the finger joints is 90°. The angle at which the finger joints bend can be captured. Firstly, the prototype design, forward kinematics and force analysis of phalanges are described in detail. In order to achieve an adaptive motion pattern similar to that of the human hand, this paper investigates the optimization of the torsion spring stiffness coefficient so that the metacarpophalangeal (MCP) joints, proximal interphalangeal (PIP) joints, and distal interphalangeal (DIP) joints of the bionic finger meet a motion ratio of approximately 3:3:1. Then, in order to realize the joint angle measurement in the process of grasping an object, the mechanical-sensor integrated finger joint is designed, and the composition, angle measurement principle and measurement circuit are introduced in detail. Finally, joint angle measurement, movement law evaluation and object grasping experiments are performed to verify the validity of the designed finger. The experimental results show that the root-mean-square (RMS) of the DIP, PIP and MCP angle measurement errors are 0.36°, 0.59° and 0.32°, respectively. The designed finger is able to grasp objects with different shapes stably.

Ti6Al4V cranial prostheses in the form of patterned meshes were 3D printed by selective laser melting in an argon environment; using a CO2 laser source and micron-sized Ti6Al4V powder as the starting material. The size and shape of prostheses were chosen based on actual computer tomography images of patient skull fractures supplied in the framework of a collaboration with a neurosurgery clinic. After optimizations of scanning speed and laser parameters, the printed material was defect-free (as shown by metallographic analyses) and chemically homogeneous, without elemental segregation or depletion. The prostheses were coated by radio-frequency magnetron sputtering (RF-MS) with a bioactive thin layer of hydroxyapatite using a bioceramic powder derived from biogenic resources (Bio-HA). Initially amorphous, the films were converted to fully-crystalline form by applying a post-deposition thermal-treatment at 500 °C/1 h in air. The X-ray diffraction structural investigations indicated the phase purity of the deposited films composed solely of a hexagonal hydroxyapatite-like compound. On the other hand, the Fourier transform infrared spectroscopic investigations revealed that the biological carbonatation of the bone mineral phase was well-replicated in the case of crystallized Bio-HA RF-MS implant coatings. The in vitro acellular assays, performed in both the fully inorganic Kokubo’s simulated body fluid and the biomimetic organic–inorganic McCoy’s 5A cell culture medium up to 21 days, emphasized both the good resistance to degradation and the biomineralization capacity of the films. Further in vitro tests conducted in SaOs-2 osteoblast-like cells showed a positive proliferation rate on the Bio-HA RF-MS coating along with a good adhesion developed on the biomaterial surface by elongated membrane protrusions.

Biomimetic flexible tactile sensors endow prosthetics with the ability to manipulate objects, similar to human hands. However, it is still a great challenge to selectively respond to static and sliding friction forces, which is crucial tactile information relevant to the perception of weight and slippage during grasps. Here, inspired by the structure of fingerprints and the selective response of Ruffini endings to friction forces, we developed a biomimetic flexible capacitive sensor to selectively detect static and sliding friction forces. The sensor is designed as a novel plane-parallel capacitor, in which silver nanowire–3D polydimethylsiloxane (PDMS) electrodes are placed in a spiral configuration and set perpendicular to the substrate. Silver nanowires are uniformly distributed on the surfaces of 3D polydimethylsiloxane microcolumns, and silicon rubber (Ecoflex®) acts as the dielectric material. The capacitance of the sensor remains nearly constant under different applied normal forces but increases with the static friction force and decreases when sliding occurs. Furthermore, aiming at the slippage perception of neuroprosthetics, a custom-designed signal encoding circuit was designed to transform the capacitance signal into a bionic pulsed signal modulated by the applied sliding friction force. Test results demonstrate the great potential of the novel biomimetic flexible sensors with directional and dynamic sensitivity of haptic force for smart neuroprosthetics.

Brachial plexus injuries with multiple-root involvement lead to severe and long-lasting impairments in the functionality and appearance of the affected upper extremity. In cases, where biologic reconstruction of hand and arm function is not possible, bionic reconstruction may be considered as a viable clinical option. Bionic reconstruction, through a careful combination of surgical augmentation, amputation, and prosthetic substitution of the functionless hand, has been shown to achieve substantial improvements in function and quality of life. However, it is known that long-term distortions in the body image are present in patients with severe nerve injury as well as in prosthetic users regardless of the level of function. To date, the body image of patients who voluntarily opted for elective amputation and prosthetic reconstruction has not been investigated. Moreover, the degree of embodiment of the prosthesis in these patients is unknown. We have conducted a longitudinal study evaluating changes of body image using the patient-reported Body Image Questionnaire 20 (BIQ-20) and a structured questionnaire about prosthetic embodiment. Six patients have been included. At follow up 2.5–5 years after intervention, a majority of patients reported better BIQ-20 scores including a less negative body evaluation (5 out of 6 patients) and higher vital body dynamics (4 out of 6 patients). Moreover, patients described a strong to moderate prosthesis embodiment. Interestingly, whether patients reported performing bimanual tasks together with the prosthetic hand or not, did not influence their perception of the prosthesis as a body part. In general, this group of patients undergoing prosthetic substitution after brachial plexus injury shows noticeable inter-individual differences. This indicates that the replacement of human anatomy with technology is not a straight-forward process perceived in the same way by everyone opting for it.

Introduction: Many adults who had a severe Narakas IV obstetric brachial plexus injury (OBPI) suffer from extensive impairments in daily living due to limited hand-arm function. The dramatic loss of axonal support at this very early age of development often render the entire extremity a biologic wasteland and reconstructive methods and therapies often fail to recover any functional hand use. In this scenario bionic reconstruction, including an elective amputation and a subsequent prosthetic fitting, may enable functional improvement in adults suffering from the consequences of such severe brachial plexus injuries. We here describe our experience in treating such patients and lay out the surgical rational and rehabilitation protocol exemplified in one patient.Case Presentation/Methods: A 27-year-old adult with a unilateral OBPI contacted our center. He presented with globally diminished function of the affected upper extremity with minimal hand activity, resulting in an inability to perform various tasks of daily living. No biological reconstructive efforts were available to restore meaningful hand function. An interdisciplinary evaluation, including a psychosocial assessment, was used to assess eligibility for bionic reconstruction. Before the amputation and after the prosthetic fitting functional assessments and self-reported questionnaires were performed.Results: One month after the amputation and de-rotation osteotomy of the humerus the patient was fitted with a myoelectric prosthesis. At the 1.5 year-follow-up assessment, the patient presented with a distinct improvement of function: the ARAT improved from 12 to 20 points, SHAP score improved from 8 to 29, and the DASH value improved from 50 to 11.7. The average wearing times of the prosthesis were 5 to 6 h per day (on 4–5 days a week).Discussion: The options for adults suffering from the consequences of severe OBPIs to improve function are limited. In selected patients in whom the neurological deficit is so severe that biologic hand function is unsatisfactory, an elective amputation and subsequent restoration of the hand with mechatronic means may be an option. The follow-up results indicate that this concept can indeed lead to solid hand function and independence in daily activities after amputation, subsequent prosthetic fitting, and rehabilitation.

The use of the bionic hand requires an extensive training procedure which is a major challenge for patients. The patients need to learn to control the bionic hand before starting using it, therefore, training should be done efficiently. One of the proposed methods is controlling the virtual bionic hand via physical EMG (electromyography) sensors. In general, one of the main problems of any prosthesis is the classification of the patient's finger movements. For this reason, some well-known machine learning algorithms are discussed. Comparative analysis of machine learning algorithms is performed, the best-selected algorithm is used for the system later. The classifier for finger movement classification is trained and tested. The virtual model of the bionic hand has been developed. The kinematics of bionic fingers is analyzed. The bionic finger performs tasks in the Cartesian space, whereas actuators work in the Quaternion (joint) space. It is necessary to transform the coordinate system from Cartesian to joint space and vice versa․ The inverse and forward kinematics is obtained by using the geometry approach and the Denavit - Hartenberg (DH) methods accordingly. The control system is designed for the virtual bionic hand model. The developed method gives an opportunity to classify all the movements of fingers via two surface EMG electrodes with an ML (Machine learning) based or the NN (Neural Network) classifier, and to control the designed bionic hand model in the MATLAB / Simulink environment.

Enhancing the embodiment of artificial limbs—the individuals' feeling that a virtual or robotic limb is integrated in their own body scheme—is an impactful strategy for improving prosthetic technology acceptance and human-machine interaction. Most studies so far focused on visuo-tactile strategies to empower the embodiment processes. However, novel approaches could emerge from self-regulation techniques able to change the psychophysiological conditions of an individual. Accordingly, this pilot study investigates the effects of a self-regulated breathing exercise on the processes of body ownership underlying the embodiment of a virtual right hand within a Spatially Augmented Respiratory Biofeedback (SARB) setting. This investigation also aims at evaluating the feasibility of the breathing exercise enabled by a low-cost SARB implementation designed for upcoming remote studies (a need emerged during the COVID-19 pandemic). Twenty-two subjects without impairments, and two transradial prosthesis users for a preparatory test, were asked (in each condition of a within-group design) to maintain a normal (about 14 breaths/min) or slow (about 6 breaths/min) respiratory rate to keep a static virtual right hand “visible” on a screen. Meanwhile, a computer-generated sphere moved from left to right toward the virtual hand during each trial (1 min) of 16. If the participant's breathing rate was within the target (slow or normal) range, a visuo-tactile event was triggered by the sphere passing under the virtual hand (the subjects observed it shaking while they perceived a vibratory feedback generated by a smartphone). Our results—mainly based on questionnaire scores and proprioceptive drift—highlight that the slow breathing condition induced higher embodiment than the normal one. This preliminary study reveals the feasibility and potential of a novel psychophysiological training strategy to enhance the embodiment of artificial limbs. Future studies are needed to further investigate mechanisms, efficacy and generalizability of the SARB techniques in training a bionic limb embodiment.

AbstractNotwithstanding the advancement of modern bionic hands and the large variety of prosthetic hands in the market, commercial devices still present limited acceptance and percentage of daily use. While commercial prostheses present rigid mechanical structures, emerging trends in the design of robotic hands are moving towards soft technologies. Although this approach is inspired by nature and could be promising for prosthetic applications, there is scant literature concerning its benefits for end-users and in real-life scenarios. In this work, we evaluate and assess the role and the benefits of soft robotic technologies in the field of prosthetics. We propose a thorough comparison between rigid and soft characteristics of two poly-articulated hands in 5 non-expert myo-electric prosthesis users in pre- and post-therapeutic training conditions. The protocol includes two standard functional assessments, three surveys for user-perception, and three customized tests to evaluate the sense of embodiment. Results highlight that rigid hands provide a more precise grasp, while soft properties show higher functionalities thanks to their adaptability to different requirements, intuitive use and more natural execution of activities of daily living. This comprehensive evaluation suggests that softness could also promote a quick integration of the system in non-expert users.

During a current project, a fully functioning prototype of a 3D printed bionic hand was developed. This paper explains principles such as: bionic hand movement, working rules of sensors and actuators etc. Design of all parts are performed, including the wiring of control system. The project includes two types of sensor control systems for bionic hand. One is with stretch sensors that replicates movement of human hand onto the bionic model. Other type is using machine learning (AI) and a camera. The average amputee cost is $30.000,00 for a new custom-built arm/hand. With the advancement of technology through time, manufacturing processes became cheaper and more accessible. Technical innovation of this project was the fact, that a functional prosthetic hand prototype was built for price lower than $50,00. The prototype does not have all the functions and capabilities as the full priced custom prosthetic hand, but it can replicate altogether the movements as the real device. All the fingers are capable of moving individually, sideways and with the work on the new version, gripping function could be perfected. Further work on materials, could help find the adequate material to increase friction and thusly enhance the grasp strength. The new challenge would involve testing with different kinds of materials to improve the working stability. As it was already unfavorable, this project was mostly based onto the actuation part, or rather the hand itself. Second part of research would involve exploring of different sensor systems. Two control solutions were designed and tested. Next steps would involve neurotransmission sensors, where arm would be controlled using brainwaves as signals that are transformed in movement.

Abstract Background Despite important advancements in control and mechatronics of myoelectric prostheses, the communication between the user and his/her bionic limb is still unidirectional, as these systems do not provide somatosensory feedback. Electrotactile stimulation is an attractive technology to close the control loop since it allows flexible modulation of multiple parameters and compact interface design via multi-pad electrodes. However, the stimulation interferes with the recording of myoelectric signals and this can be detrimental to control. Methods We present a novel compact solution for simultaneous recording and stimulation through dynamic blanking of stimulation artefacts. To test the system, a feedback coding scheme communicating wrist rotation and hand aperture was developed specifically to stress the myoelectric control while still providing meaningful information to the subjects. Ten subjects participated in an experiment, where the quality of closed-loop myoelectric control was assessed by controlling a cursor in a two degrees of freedom target-reaching task. The benchmark performance with visual feedback was compared to that achieved by combining visual feedback and electrotactile stimulation as well as by using electrotactile feedback only. Results There was no significant difference in performance between visual and combined feedback condition with regards to successfully reached targets, time to reach a target, path efficiency and the number of overshoots. Therefore, the quality of myoelectric control was preserved in spite of the stimulation. As expected, the tactile condition was significantly poorer in completion rate (100/4% and 78/25% for combined and tactile condition, respectively) and time to reach a target (9/2 s and 13/4 s for combined and tactile condition, respectively). However, the performance in the tactile condition was still good, with no significant difference in path efficiency (38/8%) and the number of overshoots (0.5/0.4 overshoots), indicating that the stimulation was meaningful for the subjects and useful for closed-loop control. Conclusions Overall, the results demonstrated that the developed system can provide robust closed-loop control using electrotactile stimulation. The system supports different encoding schemes and allows placing the recording and stimulation electrodes next to each other. This is an important step towards an integrated solution where the developed unit will be embedded into a prosthetic socket.

The word “prosthetic” has its origins as a mathematical term. According to scholar Brandon W. Hawk, Plato uses the words prosthesis and prostithenai in Phaedo to mean "addition, add to, to place", and Aristotle uses it in a similar, algebraic sense in the Metaphysics. Later, as the word appears in classical Latin, it is used as a grammatical and rhetorical term, in the sense of a letter or syllable that is added on to a word, usually the addition of a syllable to the beginning of a word, hence pro-thesis (Hawk). This is the sense of the word that was “inherited … by early modern humanists”, says Hawk, but when it appears in Edward Phillips's The New World of English Words: Or, a General Dictionary (1706), we can see how, with advances in technology, it changes from a grammatical/linguistic term into a medical term. What was once word is now made flesh:Prosthesis, a Grammatical Figure, when a Letter or Syllable is added to the beginning of a Word, as Gnatus for natus, tetuli for tuli, &c. In Surgery, Prosthesis is taken for that which fills up what is wanting, as is to beseen in fistulous and hollow Ulcers, filled up with Flesh by that Art: Also themaking of artificial Legs and Arms, when the natural ones are lost.Hawk also points to P. Dionis in Course Chirurg (a 1710 textbook detailing the art of chirurgy, or surgery, as it’s known now), who uses the word to denote one type of surgical operation; that is, prosthesis becomes not a word, but an act that “adds what is deficient”, an act that repairs loss, that “fills up what is wanting”, that fills up what is “hollow”, that “fills up with flesh”. R. Brookes, in his Introduction to Physic and Surgery (1754), is the first to define prosthesis as both an act and also as a separate, material object; it is “an operation by which some instrument is added to supply the Defect of a Part which is wanting, either naturally or accidentally”. It is not until the twentieth century (1900, to be exact), though, that the word begins to refer solely to a device or object that is added on to somehow “supply the defect”, or fill up what which is “wanting”. So etymologically we move from the writer creating a new literary device, to the scientist/doctor acting in order to fix something, then back to the device again, this time as tangible object that fills a gap where there is lack and loss (Hawk).This is how we most often see the word, and so we have the notion of prosthetic used in this medicalised sense, as an "instrument", in relation to people with missing or disfunctional limbs. Having a prosthetic arm or leg in an ableist society instantly marks one as "missing" something, or being "disabled". Wheelchairs and other prosthetic accoutrements also serve as a metonymic shorthand for disability (an example of this might be how, on reserved parking spots in North America, the image on the sign is that of a person in a wheelchair). In the case of deaf people, who are also thought of as "disabled", but whose supposed disability is invisible, hearing aids and cochlear implants (CIs) serve as this kind of visible marker.* Like artificial limbs and wheelchairs, these "instruments" (they are actually called “hearing instruments” by audiologists) are sometimes added on to the purportedly “lacking” body. They are objects that “restore function to” the disabled deaf ear. As such, these devices, like wheelchairs and bionic arms, also serve as a shorthand in American culture, especially in film and visual media, where this kind of obvious, material symbolism is very helpful in efficiently driving narrative along. David L. Mitchell and Sharon T. Snyder call this kind of disability shorthand "narrative prosthesis". In their 2001 book of the same name, they demonstrate that disability and the markers of disability, far from being neglected or omitted (as has been claimed by critics like Sarah Ruiz-Grossman), actually appear in literature and film to the point where they are astonishingly pervasive. Unlike other identities who are vastly underrepresented, Mitchell and Snyder note, images of disability are almost constantly circulated in print and visual media (this is clearly demonstrated in older film studies such as John Schuchman's Hollywood Speaks and Martin Norden's Cinema of Isolation, as well). The reason that this happens, Mitchell and Snyder say, is because almost all narrative is structured around the idea of a flaw in the natural order, the resolution of that flaw, and the restoration of order. This flaw, they show, is more often than not represented by a disabled character or symbol. Disability, then, is a "crutch upon which literary narratives lean for their representational power, disruptive potentiality and analytical insight" (49). And, in the end, all narrative is thus dependent upon some type of disability used as a prosthetic, which serves not only to “fill in” lack, but also to restore and reinforce normalcy. They also state that concepts of, and characters with, disability are therefore used in literature and film primarily as “opportunist metaphorical device(s)” (205). Hearing aids and CIs are great examples of "opportunist" devices used on television and in movies, mostly as props or “add-ons” in visual narratives. This "adding on" is done, more often than not, to the detriment of providing a well rounded narrative about the lived experience of deaf people who use such devices on a daily basis. There are countless examples of this in American television shows and films (in an upward trend since 2000), including many police and crime dramas where a cochlear implant device-as-clue stands in for the dead victim’s identity (Kincheloe "Do Androids"). We see it in movies, most notably in 2018’s A Quiet Place, in which a CI is weaponized and used to defeat the alien monster/Other (as opposed to the deaf heroine doing it by herself) (Kincheloe "Tired Tropes"). In 2019's Toy Story 4, there is a non-signing child who we know is deaf because they wear a CI. In the 2019 animated Netflix series, Undone, the main character wears a CI, and it serves as one of several markers (for her and the viewer) of her possible psychological breakdown.It seems fairly obvious that literal prostheses such as hearing aids and CI devices are used as a form of media shorthand to connote hearing ideas of “deafness”. It also might seem obvious that, as props that reinforce mainstream, ableist narratives, they are there to tell us that, in the end, despite the aesthetic nervousness that disability produces, "things will be okay". It's "fixable". These are prosthetics that are easily identified and easily discussed, debated, and questioned.What is perhaps not so obvious, however, is that American Sign Language (ASL), is also used in media as a narrative prosthetic. Lennard Davis' discussion of Erving Goffman’s idea of “stigma” in Enforcing Normalcy supports the notion that sign language, like hearing aids, is a marker. When seen by the hearing, non-signing observer, sign language "stigmatizes" the signing deaf person (48). In this sense, ASL is, like a hearing aid, a tangible "sign" of deaf identity. I would then argue that ASL is, like hearing aids and CIs, used as a "narrative prosthesis" signifying deafness and disability; its insertion allows ableist narratives to be satisfyingly resolved. Even though ASL is not a static physical device, but a living language and an integral part of deaf lived experience, it is casually employed almost everywhere in media today as a cheap prop, and as such, serves narrative purposes that are not in the best interest of realistic deaf representation. Consider this example: On 13 April 2012, Sir Paul McCartney arranged for a special event at his daughter Stella McCartney’s ivy-covered store in West Hollywood. Stars and friends like Jane Fonda, Gwyneth Paltrow, Chris Martin, Quincy Jones, and Reese Witherspoon sipped cucumber margaritas and nibbled on a spread of vegetarian Mexican appetizers. Afterwards, McCartney took them all to a tent set up on the patio out back, where he proudly introduced a new video, directed by himself. This was the world premiere of the video for "My Valentine", a song from his latest (some might say oddly titled) album, Kisses from the Bottom, a song he had originally written for and sung to new wife Nancy Shevell, at their 2011 wedding.The video is very simply shot in black and white, against a plain grey backdrop. As it begins, the camera fades in on actor Natalie Portman, who is seated, wearing a black dress. She stares at the viewer intently, but with no expression. As McCartney’s voiced-over vocal begins, “What if it rained/We didn’t care…”, she suddenly starts to mouth the words, and using sign language. The lens backs up to a medium shot of her, then closes back in on a tight close up of just her hands signing “my valentine” on her chest. There is then a quick cut to actor Johnny Depp, who is sitting in a similar position, in front of a grey backdrop, staring directly at the camera, also with no expression. There is a fade back to Portman’s face, then to her body, a close up of her signing the word “appear”, and then a cut back to Depp. Now he starts signing. Unlike Portman, he does not mouth the words, but stares ahead, with no facial movement. There is then a series of jump cuts, back and forth, between shots of the two actors’ faces, eyes, mouths, hands. For the solo bridge, there is a closeup on Depp’s hands playing guitar – a cut to Portman’s face, looking down – then to her face with eyes closed as she listens. here is some more signing, we see Depp’s impassive face staring at us again, and then, at the end, the video fades out on Portman’s still figure, still gazing at us as well.McCartney told reporters that Stella had been the one to come up with the idea for using sign language in the video. According to the ASL sign language coach on the shoot, Bill Pugin, the choice to include it wasn’t that far-fetched: “Paul always has an interpreter on a riser with a spot for his concerts and Stella loves sign language, apparently” ("The Guy Who Taught Johnny Depp"). Perhaps she made the suggestion because the second stanza contains the words “I tell myself that I was waiting for a sign…” Regardless, McCartney advised her father to “ring Natalie up and just ask her if she will sign to your song”. Later realizing he wanted another person signing in the video, Paul McCartney asked Johnny Depp to join in, which he did. When asked why he chose those two actors, McCartney said, “Well, they’re just nice people, some friends from way back and they were just very kind to do it”. A week later, they all got together with cinematographer Wally Pfister, who filmed Inception and The Dark Knight, behind the camera. According to the official press release about the video, posted on McCartney’s website, the two actors then "translate[d] the lyrics of the song into sign language – each giving distinctly different performances, making ... compelling viewing" ("Paul McCartney Directs His Own"). The response to the video was quite positive; it immediately went viral on YouTube (the original posting of it got over 15 million views). The album made it to number five on the Billboard charts, with the single reaching number twenty. The album won a 2013 Grammy Award for Best Traditional Pop Vocal album, and the video Best Music Film (“Live Kisses”). McCartney chose to sing that particular song from the album on the award show itself, and four years later, he featured both the song and video as part of his 31 city tour, the 2017 One on One concert, in which he made four million dollars a city. All told the video has served McCartney quite well.But…For whom the sign language? And why? The video is not meant for deaf eyes. When viewed through a deaf lens, it is not, by any stretch of the imagination, “compelling”; it isn’t even comprehensible. It is so bad, in fact, that the video, though signed, is also captioned for the deaf and hard of hearing. To the untrained, “hearing” eye, the signing seems to be providing a “deaf translation” of what is being sung. But it is in fact a pantomime. The actors are quite literally “going through the motions”. One egregious example of this is how, at the end of the video, when Depp thinks he’s signing “valentine”. it looks like he's saying “fuck-heart” (several media sources politely reported that he’d signed “enemy”). Whatever he did, it’s not a sign. In response to criticism of his signing, Depp said nonchalantly, “Apparently, instead of ‘love' I might have said, ‘murder'” ("Johnny Depp Says"). That wasn’t the only point of confusion, though: the way Portman signs “then she appears” was misunderstood by some viewers to be the sign for “tampon”. She actually signed it correctly, but media sources from MTV.com, to the Washington Post, “signsplained” that she had just gotten a bit confused between ASL and BSL signs (even though the BSL for “appears” bears no resemblance to what she did, and the ASL for tampon, while using the same classifier, is also signed quite differently). Part of the problem, according to sign coach Pugin, was that he and Depp “had about fifteen minutes to work on the song. I signed the song for hours sitting on an apple box under the camera for Johnny to be able to peripherally see me for each take. I was his “human cue card”. Johnny’s signing turned out to be more theatrical and ‘abbreviated’ because of the time issue” ("The Guy Who Taught").Portman, perhaps taking more time to rehearse, does a better job, but “theatrical and abbreviated” indeed; the signing was just not good, despite Pugin's coaching. But to hearing eyes, it looks fine; it looks beautiful, it looks poignant and somehow mysterious. It looks the way sign language is “supposed” to look.Remember, the McCartney website claimed that the actors were “translating” the lyrics. Technically speaking, “translation” would mean that the sense of the words to the song were being rendered, fluently, from one language (English) into another (SL), for an audience receptive to the second language. In order to “translate”, the translator needs to be fluent in both of the languages involved. To be clear, what Depp and Portman were doing was not translation. They are hearing people, not fluent in sign language, acting like signers (something that happens with dismaying regularity in the entertainment industry). Depp, to his credit, knew he wasn’t “translating”, in fact, he said "I was only copying what the guy showed me”. “But”, he says, "it was a gas – sign language is apparently very interpretive. It's all kind of different" (italics mine) ("Johnny Depp Passes the Buck"). Other than maybe being an embellishment on that one line, “I tell myself that I was waiting for a sign…”, the sentiments of McCartney’s song have absolutely nothing to do with ASL or deaf people. And he didn’t purposefully place sign language in his video as a way to get his lyrics across to a deaf audience. He’s a musician; it is fairly certain that the thought of appealing to a deaf audience never entered his or his daughter’s mind. It is much more likely that he made the decision to use sign language because of its cool factor; its emo “novelty”. In other words, McCartney used sign language as a prop – as a way to make his song “different”, more “touching”, more emotionally appealing. Sign adds a je ne sais quoi, a little “something”, to the song. The video is a hearing person’s fantasy of what a signing person looks like, what sign language is, and what it does. McCartney used that fantasy, and the sentimentality that it evokes, to sell the song. And it worked. This attitude toward sign language, demonstrated by the careless editing of the video, Depp’s flippant remarks, and the overall attitude that if it’s wrong it’s no big deal, is one that is pervasive throughout the entertainment and advertising industries and indeed throughout American culture in the U.S. That is, there is this notion that sign language is “a gas”. It’s just a “different” thing. Not only is it “different”, but it is also a “thing”, a prop, a little exotic spice you throw into the pot. It is, in other words, a "narrative prosthesis", an "add-on". Once you see this, it becomes glaringly apparent that ASL is not viewed in mainstream American culture as the language of a group of people, but instead is widely used and commodified as a product. The most obvious form of commodification is in the thousands of ASL products, from Precious Moment figurines, to Baby Signing videos, to the ubiquitous “I LOVE YOU” sign seen on everything from coffee mugs to tee shirts, to Nike posters with “Just Do It” in fingerspelling. But the area in which the language is most often commodified (and perhaps most insidiously so) is in the entertainment industry, in visual media, where it is used by writers, directors and actors, not to present an accurate portrait of lived deaf experience and language, but to do what Paul McCartney did, that is, to insert it just to create a “different”, unique, mysterious, exotic, heartwarming spectacle. Far too often, this commodification of the language results in weirdly distorted representations of what deaf people and their language actually are. You can see this everywhere: ASL is a prominent narrative add-on in blockbuster films like the aforementioned A Quiet Place; it is used in the Oscar winning The Shape of Water, and in Wonderstruck, and Baby Driver as well; it is used in the indie horror film Hush; it is used in a lot of films with apes (the Planet of the Apes series and Rampage are two examples); it is displayed on television, mostly in police dramas, in various CSI programs, and in series like The Walking Dead and Castle Rock; it is used in commercials to hawk everything from Pepsi to hotel chains to jewelry to Hormel lunchmeat to fast food (Burger King, Chik Fil A); it is used and commented on in interpreted concerts and music videos and football halftime shows; it is used (often misused) in PSAs for hurricanes and police stops; it is used in social media, from vlogs to cochlear implant activation videos. You can find ASL seemingly everywhere; it is being inserted more and more into the cultural mainstream, but is not appearing as a language. It is used, nine times out of ten, as a decorative ornament, a narrative prop. When Davis discusses the hearing perception of ASL as a marker or visible stigma, he points out that the usual hearing response to observing such stigma is a combination of a Freudian attraction/repulsion (the dominant response being negative). Many times this repulsion results from the appeal to pathos, as in the commercials that show the poor isolated deaf person with the nice hearing person who is signing to them so that they can now be part of the world. The hearing viewer might think to themselves "oh, thank God I'm not deaf!"Davis notes that, in the end, it is not the signer who is the disabled one in this scenario (aside from the fact that many times a signing person is not in fact deaf). The hearing, non signing observer is actually the one “disabled” by their own reaction to the signing “other”. Not only that, but the rhetorical situation itself becomes “disabled”: there is discomfort – wariness of language – laughter – compulsive nervous talking – awkwardness – a desire to get rid of the object. This is a learned response. People habituated, Davis says, do not respond this way (12-13). While people might think that the hearing audience is becoming more and more habituated because ASL is everywhere, the problem is that people are being incorrectly habituated. More often than not, sign language, when enfolded into narratives about hearing people in hearing situations, is put into service as a prop that can mitigate such awkward moments of possible tension and conflict; it is a prosthetic that "fills the gap", allowing an interaction between hearing and deaf people that almost always allows for a positive, "happy" resolution, a return to "normalcy", the very purpose of the "narrative prosthetic" as posited by Mitchell and Snyder. Once we see how ASL is being employed in media mostly as a narrative prosthesis, we can, as Mitchell and Snyder suggest we do (what I hope this essay begins to do), and that is, to begin to “undo the quick repair of disability in mainstream representations and beliefs; to try to make the prosthesis show; to flaunt its imperfect supplementation as an illusion” (8). In other words, if we can scrutinize the shorthand, and dig deeper, seeing the prosthetic for what it is, all of this seemingly exploitative commodification of ASL will be a good thing. Maybe, in “habituating” people correctly, in widening both hearing people’s exposure to ASL and their understanding of its actual role in deaf lived experience, signing will become less of a prosthetic, an object of fetishistic fascination. Maybe hearing people, as they become used to seeing signing people in real signing situations, will be less likely to walk up to deaf people they don’t know and say things like: “Oh, your language is SO beautiful”, or say, “I know sign!” (then fingerspelling the alphabet with agonising slowness and inaccuracy while the deaf person nods politely). However, if the use of ASL as a prosthetic in popular culture and visual media continues to go on unexamined and unquestioned, it will just continue to trivialise a living, breathing language. This trivialisation can in turn continue to reduce the lived experiences of deaf people to a sort of caricature, further reinforcing the negative representations of deaf people in America that are already in place, stereotypes that we have been trying to escape for over 200 years. Note* The word "deaf" is used in this article to denote the entire range of individuals with various hearing losses and language preferences, including Deaf persons and hard of hearing persons, etc. For more on these distinctions please refer to the website entry on this published by the National Association of the Deaf (NAD).ReferencesDavis, Lennard. Enforcing Normalcy. New York: Verso, 1995."The Guy Who Taught Johnny Depp and Natalie Portman Sign Language." Intimate Excellent: The Fountain Theater Blog. 18 Mar. 2012. <https://intimateexcellent.com/2012/04/18/the-guy-who-taught-johnny-depp-and-natalie-portman-sign-language-in-mccartney-video/>.Fitzgerald, Roisin. "Johnny Depp Says Sign Language Mishap Isn't His Fault." HiddenHearing Blog 14 Apr. 2012. <https://hiddenhearingireland.wordpress.com/2012/05/29/johnny-depp-says-sign-language-mishap-isnt-his-fault/>.Hawk, Brandon W. “Prosthesis: From Grammar to Medicine in the Earliest History of the Word.” Disability Studies Quarterly 38.4 (2018).McCartney, Paul. "My Valentine." YouTube 13 Apr. 2012.McGinnis, Sara. "Johnny Depp Passes the Buck on Sign Language Snafu." sheknows.com 10 May 2012. <https://www.sheknows.com/entertainment/articles/959949/johnny-depp-passes-the-buck-on-sign-language-snafu/>.Miller, Julie. "Paul McCartney on Directing Johnny Depp and Natalie Portman." Vanity Fair 14 Apr. 2012. <https://www.vanityfair.com/style/2012/04/paul-mccartney-johnny-depp-natalie-portman-my-valentine-music-video-gwyneth-paltrow>.Mitchell, David T., and Sharon L. Snyder. Narrative Prosthesis: Disabilities and the Dependencies of Discourse. Ann Arbor: U of Michigan P. 2000.Norden, Martin. F. The Cinema of Isolation: A History of Physical Disability in Movies. Rutgers UP: 1994."Paul McCartney Directs His Own My Valentine Video." paulmccartney.com 14 Apr. 2012. <https://www.paulmccartney.com/news-blogs/news/paul-mccartney-directs-his-own-my-valentine-videos-featuring-natalie-portman-and>.Ruiz-Grossman, Sarah. "Disability Representation Is Seriously Lacking in Television and the Movies: Report." Huffington Post 27 Mar. 2019. <https://www.huffpost.com/entry/disability-representation-movies-tv_n_5c9a7b85e4b07c88662cabe7>.Schuchman, J.S. Hollywood Speaks: Deafness and the Film Entertainment Industry. U Illinois P, 1999.

IntroductionWhen I saw Patriots Day (Berg 2016) at my local multiplex, a family entered the theatre and sat a few rows in front of me. They had a child with them, a boy who was perhaps nine or ten years old. Upon seeing the kid, I had a physical reaction. Not quite a knee-jerk, but more of an uneasy gut punch. ‘Don't you know what this movie is about?’ I wanted to ask his parents; ‘I’ve seen Jeff Bauman’s bones, and that is not something a child should see.’ I had lived through the 2013 Boston Marathon bombing and subsequent manhunt, and the memories were vivid in my mind as I waited for the movie to start, to re-present the memory on screen. Admittedly, I had lived through it from the other side of the world, watching through the mediated windows of the computer, smartphone, and television screen. Nevertheless, I remembered it in blood-soaked colour detail, brought to me by online photo galleries, social media updates, the failed amateur sleuths of Reddit, and constant cable news updates, breaking news even when the events had temporarily stalled. Alison Landsberg has coined the term “prosthetic memory” to describe how historical events are re-created and imbued with an affective experience through cinema and other sites of mass cultural mediation, allowing those who did not experience the past to form a personal connection to and subjective memory of history (2). For the boy in the cinema, Patriots Day would most likely be his first encounter with and memory of the Boston Marathon bombing. But how does prosthetic memory apply to audience members like me, who had lived through the Boston bombing from a great distance, with personalised memories mediated by the first-person perspective of social media? Does the ease of dissemination of information, particularly eyewitness photographs and videos, create possibilities for a prosthetic experience of the present? Does the online mediation of historical events of the present translate to screen dramatisations? These questions become particularly pertinent when the first-release audience of a film has recent, living memories of the real events depicted on screen.The time between when an event occurs and when it is brought to cinemas in a true-events adaptation is decreasing. Rebecca A. Sheehan argues that the cultural value of instant information has given rise to a trend in the contemporary biopic and historical film that sees our mediated world turned into a temporal "paradox in which the present is figured as both historical and ongoing" (36). Since 2005, Sheehan writes, biographical films that depict the lives of still-living public figures or in other ways comment on the ongoing history of the present have become increasingly frequent. Sheehan cites films such as The Social Network (Fincher 2010), The Queen (Frears 2006), W. (Stone 2008), and Game Change (Roach 2012) as examples of this growing biopic trend (35-36). In addition to the instantaneous remediation of public figures in the contemporary biopic, similarly there is a stable of contemporary historical films based on the true stories of ordinary people involved in extraordinary recent events. Films such as The Impossible (Bayona 2012), World Trade Center (Stone 2006), United 93 (Greengrass 2006), and Deepwater Horizon (Berg 2016) bring the death and destruction of real-world natural disasters or terrorist attacks to a sanitised but experiential cinematic event. The sensitive nature of some of the events in question often see the films labelled “too soon” and exploitative of recent tragedy. Films such as these typically do not have known public figures as their protagonists, but they arise from a similar climate of the demands of televisual and online mediation that Sheehan describes in the “instant biopics” of her study (36). Given this rise of brief temporal space between real events and their dramatisations, in this essay, I examine Patriots Day in light of the role digital experience plays in both its dramatisation and how the film's initial audience may remember the event. As Patriots Day replicates a kind of prosthetic memory of the present, it uses the first-instance digital mediation of the event to form prosthetic memories for future viewers. Through Patriots Day, I seek to gesture toward the possibilities of first-person digital mediation of major news events in shaping dramatisations of the recent past.Digital Memories of the Boston Marathon BombingTo examine the ways the Boston Marathon bombing circulated in online space, I look at the link- and image-based online discussion platform Reddit as an example of engagement with and recirculation of the event, particularly as a form of engagement defined by photographs and videos. Because the Boston Marathon is a televised and widely-reported event, professional videographers and photographers were present at the marathon’s finish line at the time of the first explosion. Thus, the first bomb and its immediate aftermath were captured in news footage and still images. The graphic nature of some of these images depicting the violence of the scene saw traditional print and television outlets cropping or otherwise editing the photographs to make them appropriate for mass broadcast (Hughney). Some online outlets, however, showed these pictures in their unedited form, often accompanied by warnings that required readers to scroll further down the page or click through the warning to see the photographs. These distinctive capabilities of the online environment allowed individuals to choose whether to view the image, while still allowing the uncensored image to circulate and be reposted elsewhere, such as on Reddit. In addition to photos and videos shot by professionals at the finish line, witnesses armed with smart phone cameras and access to social media posted their views of the aftermath to social media like Twitter, enabling the collation of both amateur and professionally shot photographs of the scene by online news aggregators such as Buzzfeed (Broderick). The Reddit community is seen as an essential part of the Boston Bombing story for the way some of its users participated in a form of ‘crowd-sourced’ investigation that resulted in the false identification of suspects (see: Nhan et al.; Tapia et al.; Potts and Harrison). There is another aspect to Reddit’s role in the circulation and mediation of the story, however, as online venues became a go-to source for news on the unfolding event, where information was delivered faster and with greater accuracy than the often-sensationalised television news coverage (Starbird et al. 347). In addition to its role in providing information that is a part of Reddit’s culture that “value[s] evidence of some kind” to support discussion (Potts and Harrison 144), Reddit played a number of roles in the sense-making process that social media can often facilitate during crisis situations (Heverin and Zach). Through its division into “subreddits,” the individual communities and discussion areas that make up the platform, Reddit accommodates an incredibly diverse range of topics and interests. Different areas of Reddit were able to play different roles in the process of sharing information and acting in a community sense-making capacity in the aftermath of the bombing. Among the subreddits involved in attempting to make sense of the event were those that served as appropriate places for posting image galleries of both professional and amateur photographs and videos, drawn from a variety of online sources. Users of subreddits such as /r/WTF and /r/MorbidReality, for example, posted galleries of “NSFL” (Not Safe For Life) images of the bombing and its aftermath (see: touhou_hijack, titan059, f00d4tehg0dz). Additionally, the /r/Boston subreddit issued calls for anyone with photographs or videos related to the attack to upload them to the thread, as well as providing an e-mail address to submit them to the FBI (RichardHerold). The /r/FindBostonBombers subreddit became a hub for analysis of the photographs. The subreddit's investigatory work was picked up by other online and traditional media outlets (including the New York Post cover photo which misidentified two suspects), bringing wider attention to Reddit’s unfolding coverage of the bombing (Potts and Harrison 148). Landsberg’s theory of prosthetic memory, and her application of it, largely relates to mass culture’s role in “the production and dissemination of memories that have no direct connection to a person’s lived past” (20). The possibilities for news events to be recorded and disseminated by smart phones and social media, however, help to create a deeper sense of affective engagement with a distant present, creating prosthetic memories out of the mediated first-hand experiences of others. The graphic nature of the photos and videos of the Boston bombing collected by and shared on sites like Reddit, the ongoing nature of the event (which, from detonation to the capture of Dzokhar Tsarnaev, spanned five days), and the participatory activity of scouring photographs for clues to the identity of the bombers all lend a sense of ongoing, experiential engagement with first-person, audiovisual mediations of the event. These prosthetic memories of the present are, as Landsberg writes of those created from dramatisations or re-creations of the past, transferable, able to belong to those who have no “natural” claim to them (18) with an experiential element that personalises history for those who do not directly experience it (33). If widely disseminated first-person mediations of events like the Boston bombing can be thought of as a prosthetic experience of present history, how will they play a part in the prosthetic memories of the future? How will those who did not live through the Boston bombing, either as a personal experience or a digitally mediated one, incorporate this digital memory into their own experience of its cinematic re-creation? To address this question, I turn to consider Patriots Day. Of particular note is the bombing sequence’s resemblance to digital mediations of the event as a marker of a plausible docudramatic resemblance to reality.The Docudramatic Re-Presentation of Digital MemoryAs a cinematic representation of recent history, Patriots Day sits at a somewhat uncomfortable intersection of fact and fiction, of docudrama and popcorn action movie, more so than an instant history film typically would. Composite characters or entirely invented characters and narratives that play out against the backdrop of real events are nothing out of the ordinary in the historical film. However, Patriots Day's use of real material and that of pure invention coincides, frequently in stark contrast. The film's protagonist, Boston Police Sergeant Tommy Saunders (played by Mark Wahlberg) is a fictional character, the improbable hero of the story who is present at every step of the attack and the manhunt. He is there on Boylston Street when the bombs go off. He is there with the FBI, helping to identify the suspects with knowledge of Boylston Street security cameras that borders on a supernatural power. He is there at the Watertown shootout among exploding cars and one-liner quips. When Dzokhar Tsarnaev is finally located, he is, of course, first on the scene. Tommy Saunders, as embodied by Wahlberg, trades on all the connotations of both the stereotypical Boston Southie and the action hero that are embedded in Wahlberg’s star persona. As a result, Patriots Day often seems to be a depiction of an alternate universe where Mark Wahlberg in a cop uniform almost single-handedly caught a terrorist. The improbability of Saunders as a character in a true-events drama, though, is thoroughly couched in the docudramatic material of historical depiction. Steven N. Lipkin argues that docudrama is a mode of representation that performs a re-creation of memory to persuade us that it is representing the real (1). By conjuring the memory of an event into being in ways that seem plausible and anchored to the evidence of actuality—such as integrating archival footage or an indexical resemblance to the actual event or an actual person—the representational, cinematic, or fictionalised elements of docudrama are imbued with a sense of the reality they claim to represent (Lipkin 3). Patriots Day uses real visual material throughout the film. The integration of evidence is particularly notable in the bombing sequence, which combines archival footage of the 2013 race, surveillance footage of the Tsarnaev brothers approaching the finish line, and a dramatic re-creation that visually resembles the original to such an extent that its integration with archival footage is almost seamless (Landler). The conclusion of the film draws on this evidential connection to the real as well, in the way that docudrama is momentarily suspended to become documentary, as interviews with some of the real people who are depicted as characters in the film close out the story. In addition to its direct use of the actual, Patriots Day's re-creation of the bombing itself bears an indexical resemblance to the event as seen by those who were not there and relies on memories of the bombing's initial mediation to vouch for the dramatisation's accuracy. In the moments before the bombing's re-creation, actual footage of the Tsarnaevs's route down Boylston Street plays, a low ominous tone of the score building over the silent security footage. The fictional Saunders’s fictional wife (Michelle Monaghan) has come to the finish line to bring him a knee brace, and she passes Tamerlan Tsarnaev as she leaves. This shot directly crosses a visual resemblance to the actual (Themo Melikidze playing Tsarnaev, resembling the bomber through physicality and costuming) with the fictional structuring device of the film in the form of Tommy Saunders. Next, in a long shot, we see Tsarnaev bump into a man wearing a grey raglan shirt. The man turns to look at Tsarnaev. From the costuming, it is evident that this man who is not otherwise named is intended to represent Jeff Bauman, the subject of an iconic photograph from the bombing. In the photo, Bauman is shown being taken from the scene in a wheelchair with both legs amputated from below the knee by the blast (another cinematic dramatisation of the Boston bombing, Stronger, based on Bauman’s memoir of the same name, will be released in 2017). In addition to the visual signifier of Bauman from the memorable photograph, reports circulated that Bauman's ability to describe Tsarnaev to the FBI in the immediate aftermath of the bombing was instrumental in identifying the suspects (Hartmann). Here, this digital memory is re-created in a brief but recognisable moment: this is the before picture of Jeff Bauman, this is the moment of identification that was widely circulated and talked about, a memory of that one piece of good news that helped satisfy public curiosity about the status of the iconic Man in the Wheelchair.When the bombs detonate, we are brought into the smoke and ash, closer access than the original mediation afforded by the videographers at the finish line. After the first bomb detonates, the camera follows Saunders as he walks toward the smoke cloud. As the second bomb explodes, we go inside the scene. The sequence cuts from actual security camera footage that captured the blast, to a first-person perspective of the explosion, the resulting fire and smoke, and a shot that resembles the point of view of footage captured on a smart phone. The frame shakes wildly, giving the viewer disorienting flashes of the victims, a sense of the chaos without seeing anything in lasting, specific detail, before the frame tips sideways onto the pavement, stained with blood and littered with debris. Coupled with this is a soundscape that resembles both the subjective experience of a bombing victim and what their smart phone video has captured. There is the rumble of the explosion and muffled sounds of debris hidden under the noise of shockwaves of air hitting a microphone, fading into an electronic whine and tinnitus ring. A later shot shows the frame obscured by smoke, slowly clearing to give us a high angle view of the aftermath, resembling photographs taken from a window overlooking the scene on Boylston Street (see: touhou_hijack). Archival footage of first responders and points of view resembling a running cell phone camera that captures flashes of blood and open wounds combine with shots of the actors playing characters (both fictional and based on real people) that were established at the beginning of the film. There is once again a merging of the re-created and the actual, bound together by a sense of memory that encourages the viewer to take the former as plausible, based on its resemblance to the latter.When Saunders runs for the second bombing site further down the street, he looks down at two bodies on the ground. Framed in close-up, the bloodless, empty expression and bright blue shirt of Krystle Campbell are recognisable. We can ignore the inaccuracies of this element of the digital memory amidst the chaos of the sequence. Campbell died in the first bombing, not the second. The body of a woman in a black shirt is between the camera's position on the re-created Boylston Street and the actor standing in for Campbell, the opposite of how Campbell and her friend Karen Rand lay beside each other in photographs of the bombing aftermath. The police officer who takes Krystle's pulse on film and shakes her head at Wahlberg's character is a brunette, not the blonde in the widely-circulated picture of a first responder at the actual bombing. The most visceral portion of the image is there, though, re-created almost exactly as it appeared at its first point of mediation: the lifeless eyes and gaping mouth, the bright blue t-shirt. The memory of the event is conjured into being, and the cinematic image resembles the most salient elements of the memory enough for the cinematic image to be a plausible re-creation. The cinematic frame is positioned at a lower level to the original still, as though we are on the ground beside her, bringing the viewer even closer to the event, even as the frame crops out her injuries as scene photographs did not, granting a semblance of respectful distance from the real death. This re-creation of Krystle Campbell’s death is a brief flash in the sequence, but a powerful moment of recognition for those who remember its original mediation. The result is a sequence that shows the graphic violence of the actuality it represents in a series of images that invite its viewer to expand the sequence with their memory of the event the way most of them experienced it: on other screens, at the site of its first instance of digital mediation.ConclusionThrough its use of cinematography that resembles actual photographic evidence of the Boston Marathon bombing or imbues the re-creation with a sense of a first-person, digitally mediated account of the event, Patriots Day draws on its audience's digital memory of recent history to claim accuracy in its fictionalisation. Not everyone who sees Patriots Day may be as familiar with the wealth of eyewitness photographs and images of the Boston Marathon bombing as those who may have experienced and followed the events in online venues such as Reddit. Nonetheless, the fact of this material's existence shapes the event's dramatisation as the filmmakers attempt to imbue the dramatisation with a sense of accuracy and fidelity to the event. The influence of digital memory on the film’s representation of the event gestures toward the possibilities for how online engagement with major news events may play a role in their dramatisation moving forward. Events that have had eyewitness visual accounts distributed online, such as the 2015 Bataclan massacre, the 2016 Pulse nightclub shooting, the 2017 Manchester Arena bombing and Westminster Bridge attack, or the 2016 police shooting of Philando Castile that was streamed on Facebook live, may become the subject of future dramatisations of recent history. The dramatic renderings of contemporary history films will undoubtedly be shaped by the recent memory of their online mediations to appeal to a sense of accuracy in the viewer's memory. As recent history films continue, digital memories of the present will help make the prosthetic memories of the future. 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