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Giorgi, Andrea, Vincenzo Ronca, Alessia Vozzi, Nicolina Sciaraffa, Antonello di Florio, Luca Tamborra, Ilaria Simonetti, et al. "Wearable Technologies for Mental Workload, Stress, and Emotional State Assessment during Working-Like Tasks: A Comparison with Laboratory Technologies." Sensors 21, no. 7 (March 26, 2021): 2332. http://dx.doi.org/10.3390/s21072332.
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The capability of monitoring user’s performance represents a crucial aspect to improve safety and efficiency of several human-related activities. Human errors are indeed among the major causes of work-related accidents. Assessing human factors (HFs) could prevent these accidents through specific neurophysiological signals’ evaluation but laboratory sensors require highly-specialized operators and imply a certain grade of invasiveness which could negatively interfere with the worker’s activity. On the contrary, consumer wearables are characterized by their ease of use and their comfortability, other than being cheaper compared to laboratory technologies. Therefore, wearable sensors could represent an ideal substitute for laboratory technologies for a real-time assessment of human performances in ecological settings. The present study aimed at assessing the reliability and capability of consumer wearable devices (i.e., Empatica E4 and Muse 2) in discriminating specific mental states compared to laboratory equipment. The electrooculographic (EOG), electrodermal activity (EDA) and photoplethysmographic (PPG) signals were acquired from a group of 17 volunteers who took part to the experimental protocol in which different working scenarios were simulated to induce different levels of mental workload, stress, and emotional state. The results demonstrated that the parameters computed by the consumer wearable and laboratory sensors were positively and significantly correlated and exhibited the same evidences in terms of mental states discrimination.
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Chen, Xiaochen, Leena Ukkonen, and Johanna Virkki. "Reliability evaluation of wearable radio frequency identification tags: Design and fabrication of a two-part textile antenna." Textile Research Journal 89, no. 4 (January 11, 2018): 560–71. http://dx.doi.org/10.1177/0040517517750651.
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Passive radio frequency identification-based technology is a convincing approach to the achievement of versatile energy- and cost-efficient wireless platforms for future wearable applications. By using two-part antenna structures, the antenna-electronics interconnections can remain non-stressed, which can significantly improve the reliability of the textile-embedded wireless components. In this article, we describe fabrication of two-part stretchable and non-stretchable passive ultra-high frequency radio frequency identification textile tags using electro-textile and embroidered antennas, and test their reliability when immersed as well as under cyclic strain. The results are compared to tags with traditional one-part dipole antennas fabricated from electro-textiles and by embroidery. Based on the results achieved, the initial read ranges of the two-part antenna tags, around 5 m, were only slightly shorter than those of the one-part antenna tags. In addition, the tag with two-part antennas can maintain high performance in a moist environment and during continuous stretching, unlike the one-part antenna tag where the antenna-integrated circuit attachment is under stress.
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Tonacci, Alessandro, Lucia Billeci, Elisa Burrai, Francesco Sansone, and Raffaele Conte. "Comparative Evaluation of the Autonomic Response to Cognitive and Sensory Stimulations through Wearable Sensors." Sensors 19, no. 21 (October 27, 2019): 4661. http://dx.doi.org/10.3390/s19214661.
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Psychological stress is known to activate the autonomic nervous system (ANS), thus representing a useful target to be monitored to understand the physiological, unconscious effect of stress on the human body. However, little is known about how differently the ANS responds to cognitive and sensory stimulations in healthy subjects. To this extent, we enrolled 23 subjects and administered a stress protocol consisting of the administration of sensory (olfactory) and cognitive (mathematical) stressors. Autonomic parameters were unobtrusively monitored through wearable sensors for capturing electrocardiogram and skin conductance signals. The results obtained demonstrated an increase of the heart rate during both stress protocols, with a similar decrease of the heart rate variability. Cognitive stress test appears to affect the autonomic parameters to a greater extent, confirming its effects on the human body. However, olfactory stimulation could be useful to study stress in specific experimental settings when the administration of complex cognitive testing is not feasible.
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Liapis, Alexandros, Evanthia Faliagka, Christos P. Antonopoulos, Georgios Keramidas, and Nikolaos Voros. "Advancing Stress Detection Methodology with Deep Learning Techniques Targeting UX Evaluation in AAL Scenarios: Applying Embeddings for Categorical Variables." Electronics 10, no. 13 (June 26, 2021): 1550. http://dx.doi.org/10.3390/electronics10131550.
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Physiological measurements have been widely used by researchers and practitioners in order to address the stress detection challenge. So far, various datasets for stress detection have been recorded and are available to the research community for testing and benchmarking. The majority of the stress-related available datasets have been recorded while users were exposed to intense stressors, such as songs, movie clips, major hardware/software failures, image datasets, and gaming scenarios. However, it remains an open research question if such datasets can be used for creating models that will effectively detect stress in different contexts. This paper investigates the performance of the publicly available physiological dataset named WESAD (wearable stress and affect detection) in the context of user experience (UX) evaluation. More specifically, electrodermal activity (EDA) and skin temperature (ST) signals from WESAD were used in order to train three traditional machine learning classifiers and a simple feed forward deep learning artificial neural network combining continues variables and entity embeddings. Regarding the binary classification problem (stress vs. no stress), high accuracy (up to 97.4%), for both training approaches (deep-learning, machine learning), was achieved. Regarding the stress detection effectiveness of the created models in another context, such as user experience (UX) evaluation, the results were quite impressive. More specifically, the deep-learning model achieved a rather high agreement when a user-annotated dataset was used for validation.
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Conforti, Ilaria, Ilaria Mileti, Zaccaria Del Prete, and Eduardo Palermo. "Measuring Biomechanical Risk in Lifting Load Tasks Through Wearable System and Machine-Learning Approach." Sensors 20, no. 6 (March 11, 2020): 1557. http://dx.doi.org/10.3390/s20061557.
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Ergonomics evaluation through measurements of biomechanical parameters in real time has a great potential in reducing non-fatal occupational injuries, such as work-related musculoskeletal disorders. Assuming a correct posture guarantees the avoidance of high stress on the back and on the lower extremities, while an incorrect posture increases spinal stress. Here, we propose a solution for the recognition of postural patterns through wearable sensors and machine-learning algorithms fed with kinematic data. Twenty-six healthy subjects equipped with eight wireless inertial measurement units (IMUs) performed manual material handling tasks, such as lifting and releasing small loads, with two postural patterns: correctly and incorrectly. Measurements of kinematic parameters, such as the range of motion of lower limb and lumbosacral joints, along with the displacement of the trunk with respect to the pelvis, were estimated from IMU measurements through a biomechanical model. Statistical differences were found for all kinematic parameters between the correct and the incorrect postures (p < 0.01). Moreover, with the weight increase of load in the lifting task, changes in hip and trunk kinematics were observed (p < 0.01). To automatically identify the two postures, a supervised machine-learning algorithm, a support vector machine, was trained, and an accuracy of 99.4% (specificity of 100%) was reached by using the measurements of all kinematic parameters as features. Meanwhile, an accuracy of 76.9% (specificity of 76.9%) was reached by using the measurements of kinematic parameters related to the trunk body segment.
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Leonidis, Asterios, Maria Korozi, Eirini Sykianaki, Eleni Tsolakou, Vasilios Kouroumalis, Danai Ioannidi, Andreas Stavridakis, Margherita Antona, and Constantine Stephanidis. "Improving Stress Management and Sleep Hygiene in Intelligent Homes." Sensors 21, no. 7 (March 30, 2021): 2398. http://dx.doi.org/10.3390/s21072398.
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High stress levels and sleep deprivation may cause several mental or physical health issues, such as depression, impaired memory, decreased motivation, obesity, etc. The COVID-19 pandemic has produced unprecedented changes in our lives, generating significant stress, and worries about health, social isolation, employment, and finances. To this end, nowadays more than ever, it is crucial to deliver solutions that can help people to manage and control their stress, as well as to reduce sleep disturbances, so as to improve their health and overall quality of life. Technology, and in particular Ambient Intelligence Environments, can help towards that direction, when considering that they are able to understand the needs of their users, identify their behavior, learn their preferences, and act and react in their interest. This work presents two systems that have been designed and developed in the context of an Intelligent Home, namely CaLmi and HypnOS, which aim to assist users that struggle with stress and poor sleep quality, respectively. Both of the systems rely on real-time data collected by wearable devices, as well as contextual information retrieved from the ambient facilities of the Intelligent Home, so as to offer appropriate pervasive relaxation programs (CaLmi) or provide personalized insights regarding sleep hygiene (HypnOS) to the residents. This article will describe the design process that was followed, the functionality of both systems, the results of the user studies that were conducted for the evaluation of their end-user applications, and a discussion about future plans.
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Bello, Hymalai, Bo Zhou, and Paul Lukowicz. "Facial Muscle Activity Recognition with Reconfigurable Differential Stethoscope-Microphones." Sensors 20, no. 17 (August 30, 2020): 4904. http://dx.doi.org/10.3390/s20174904.
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Many human activities and states are related to the facial muscles’ actions: from the expression of emotions, stress, and non-verbal communication through health-related actions, such as coughing and sneezing to nutrition and drinking. In this work, we describe, in detail, the design and evaluation of a wearable system for facial muscle activity monitoring based on a re-configurable differential array of stethoscope-microphones. In our system, six stethoscopes are placed at locations that could easily be integrated into the frame of smart glasses. The paper describes the detailed hardware design and selection and adaptation of appropriate signal processing and machine learning methods. For the evaluation, we asked eight participants to imitate a set of facial actions, such as expressions of happiness, anger, surprise, sadness, upset, and disgust, and gestures, like kissing, winkling, sticking the tongue out, and taking a pill. An evaluation of a complete data set of 2640 events with 66% training and a 33% testing rate has been performed. Although we encountered high variability of the volunteers’ expressions, our approach shows a recall = 55%, precision = 56%, and f1-score of 54% for the user-independent scenario(9% chance-level). On a user-dependent basis, our worst result has an f1-score = 60% and best result with f1-score = 89%. Having a recall ≥60% for expressions like happiness, anger, kissing, sticking the tongue out, and neutral(Null-class).
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Debard, Glen, Nele De Witte, Romy Sels, Marc Mertens, Tom Van Daele, and Bert Bonroy. "Making Wearable Technology Available for Mental Healthcare through an Online Platform with Stress Detection Algorithms: The Carewear Project." Journal of Sensors 2020 (November 25, 2020): 1–15. http://dx.doi.org/10.1155/2020/8846077.
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Over the past years, mobile health (mHealth) applications and specifically wearables have become able and available to collect data of increasing quality of relevance for mental health. Despite the large potential of wearable technology, mental healthcare professionals are currently lacking tools and knowledge to properly implement and make use of this technology in practice. The Carewear project is aimed at developing and evaluating an online platform, allowing healthcare professionals to use data from wearables in their clinical practice. Carewear implements data collection through self-tracking, which is aimed at helping people in their behavioral change process, as a component of a broader intervention or therapy guided by a mental healthcare professional. The Empatica E4 wearables are used to collect accelerometer data, electrodermal activity (EDA), and blood volume pulse (BVP) in real life. This data is uploaded to the Carewear platform where algorithms calculate moments of acute stress, average resting heart rate (HR), HR variability (HRV), step count, active periods, and total active minutes. The detected moments of acute stress can be annotated to indicate whether they are associated with a negative feeling of stress. Also, the mood of the day can be elaborated on. The online platform presents this information in a structured way to both the client and their mental healthcare professional. The goal of the current study was a first assessment of the accuracy of the algorithms in real life through comparisons with comprehensive annotated data in a small sample of five healthy participants without known stress-related complaints. Additionally, we assessed the usability of the application through user reports concerning their experiences with the wearable and online platform. While the current study shows that a substantial amount of false positives are detected in a healthy sample and that usability could be improved, the concept of a user-friendly platform to combine physiological data with self-report to inform on stress and mental health is viewed positively in our pilots.
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Kwon, Yong‐Wook, Jong‐Sung Lee, Young‐Chang Joo, and Byoung‐Joon Kim. "In Twisting Motion, Stress‐Free Zone of Wearable Electronics." Advanced Electronic Materials 6, no. 3 (January 22, 2020): 1901239. http://dx.doi.org/10.1002/aelm.201901239.
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Rukasha, Tendai, Sandra I Woolley, Theocharis Kyriacou, and Tim Collins. "Evaluation of Wearable Electronics for Epilepsy: A Systematic Review." Electronics 9, no. 6 (June 10, 2020): 968. http://dx.doi.org/10.3390/electronics9060968.
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Epilepsy is a neurological disorder that affects 50 million people worldwide. It is characterised by seizures that can vary in presentation, from short absences to protracted convulsions. Wearable electronic devices that detect seizures have the potential to hail timely assistance for individuals, inform their treatment, and assist care and self-management. This systematic review encompasses the literature relevant to the evaluation of wearable electronics for epilepsy. Devices and performance metrics are identified, and the evaluations, both quantitative and qualitative, are presented. Twelve primary studies comprising quantitative evaluations from 510 patients and participants were collated according to preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Two studies (with 104 patients/participants) comprised both qualitative and quantitative evaluation components. Despite many works in the literature proposing and evaluating novel and incremental approaches to seizure detection, there is a lack of studies evaluating the devices available to consumers and researchers, and there is much scope for more complete evaluation data in quantitative studies. There is also scope for further qualitative evaluations amongst individuals, carers, and healthcare professionals regarding their use, experiences, and opinions of these devices.
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Francés-Morcillo, Leire, Paz Morer-Camo, María Isabel Rodríguez-Ferradas, and Aitor Cazón-Martín. "Wearable Design Requirements Identification and Evaluation." Sensors 20, no. 9 (May 2, 2020): 2599. http://dx.doi.org/10.3390/s20092599.
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Wearable electronics make it possible to monitor human activity and behavior. Most of these devices have not taken into account human factors and they have instead focused on technological issues. This fact could not only affect human–computer interaction and user experience but also the devices’ use cycle. Firstly, this paper presents a classification of wearable design requirements that have been carried out by combining a quantitative and a qualitative methodology. Secondly, we present some evaluation procedures based on design methodologies and human–computer interaction measurement tools. Thus, this contribution aims to provide a roadmap for wearable designers and researchers in order to help them to find more efficient processes by providing a classification of the design requirements and evaluation tools. These resources represent time and resource-saving contributions. Therefore designers and researchers do not have to review the literature. It will no be necessary to carry out exploratory studies for the purposes of identifying requirements or evaluation tools either.
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Becerra Sanchez, Enriqueta Patricia, Angelica Reyes Munoz, and Juan Antonio Guerrero Ibanez. "Wearable Sensors for Evaluating Driver Drowsiness and High Stress." IEEE Latin America Transactions 17, no. 03 (March 2019): 418–25. http://dx.doi.org/10.1109/tla.2019.8863312.
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Lee, Je-Hoon, Jai-Chang Park, and Seong-Beom Kim. "Therapeutic Exercise Platform for Type-2 Diabetic Mellitus." Electronics 10, no. 15 (July 29, 2021): 1820. http://dx.doi.org/10.3390/electronics10151820.
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Exercise enables continuous glycemic control for diabetic patients, and it is effective in preventing diabetic complications and maintaining emotional stability. However, it is difficult for diabetic patients to know the appropriate intensity and duration of exercise. Excessive exercise causes sudden hypoglycemia, and patients avoid therapeutic exercise or perform it conservatively owing to the repeated hypoglycemia symptoms. In this paper, we propose a new therapeutic exercise platform that supports type 2 diabetes patients to exercise regularly according to the exercise prescription received from the hospital. The proposed platform includes the following three significant contributions. First, we develop a hardware platform that automatically tracks and records all aerobic exercise performed by a patient indoors or outdoors using a wearable band and aerobic exercise equipment. Second, we devise a patient-specific exercise stress test to know whether the patient is exercising according to his or her usual exercise regimen. Finally, we develop a mobile application that informs patients in real-time whether they are exercising appropriately for their exercise regimen each time they exercise. For platform evaluation and future improvement, we received satisfaction ratings and functional improvements through a questionnaire survey on 10 type 2 diabetes patients and 10 persons without a diabetes diagnosis who had used the proposed platform for more than 3 months. Most users were (1) satisfied with automatic exercise recording, and (2) exercise time increased. Diabetics reported that their fasting blood glucose was dropped, and they were more motivated to exercise. These results prove that exercise must be combined with medication for blood glucose management in chronic diabetic patients. The proposed platform can be helpful for patients to continue their daily exercise according to their exercise prescription.
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Doty, Jennifer L., Sonya S. Brady, Javiera Monardez Popelka, Laura Rietveld, Diego Garcia-Huidobro, Matthew J. Doty, Roxana Linares, Maria Veronica Svetaz, and Michele L. Allen. "Designing a Mobile App to Enhance Parenting Skills of Latinx Parents: A Community-Based Participatory Approach." JMIR Formative Research 4, no. 1 (January 24, 2020): e12618. http://dx.doi.org/10.2196/12618.
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Background Latinx families are among the highest users of smartphones, yet few health-focused Web programs have been developed for this audience. Parent-based smartphone apps designed for Latinx families may help increase access to evidence-informed parenting programming and ultimately reduce health disparities among children and adolescents. To maximize uptake of such apps, the Center for eHealth Research and Disease Management (CeHRes) Roadmap for electronic health (eHealth) development recommends 5 phases of development: (1) contextual inquiry, (2) value specification, (3) design, (4) operationalization, and (5) evaluation. Objective Guided by the CeHRes Roadmap, our objective was to apply a community-based participatory research (CBPR) approach to mobile app development. We present a formative evaluation to inform the design of an eHealth mobile app for Latinx parents of adolescents based on a face-to-face parenting program, Padres Informados/Jovenes Preparados (PIJP). Methods Community participants in the process included Latinx parents and stakeholders. We conducted a parent survey (N=115) and interviews (N=20) to understand the context and obtain feedback on a mockup and prototype of the app, facilitator workshops to streamline content, and stakeholder interviews (N=4) to discuss values and app requirements. Results We report results from the first 3 phases of the CeHRes Roadmap. In the survey, 96.5% (111/115) of parents reported they had access to a cell phone, 85.6% (89/104) reported they would use a parenting app in the next month if they had access, and 80.2% (89/111) reported intentions to use a stress reduction app. Parents reported that setting goals about parenting and tracking those goals were important potential features of an app. In logistic regression analyses, technology attitudes and barriers were not related to parent’s intentions to use a parenting mobile app (95% CI 0.51-1.17 and 95% CI 0.28-2.12, respectively). Qualitative interviews confirmed Latinx parents’ technology engagement and desire for education and child development information online. Stakeholder interviews identified 3 community values: familism, the promotion of adolescent health, and delivery of economic value. Community stakeholders participated in defining the mobile app requirements. On the basis of community and parent input, the mobile app prototype was designed with 3 sections: (1) 8 modules of video-based parenting skills instruction with content from the face-to-face PIJP program, (2) breath rate information from a wearable device to support awareness of stress levels that could affect parenting, and (3) goal setting and tracking capacities. Conclusions The findings of this study highlight the utility of an iterative, participatory design process. The CBPR approach and community collaboration enhanced the CeHRes Roadmap by promoting power sharing, facilitating recruitment, and building trust among community members. Experiences applying community research to the initial 3 phases of the CeHRes Roadmap in a Latinx community are discussed, along with plans for the 2 final phases.
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Liu, Haoran, Jun Ge, Xiao Lin, Huilin Yang, and Lei Yang. "A Carbohydrate-based Elastomer with Tunable Properties for Sensing Applications." MRS Advances 3, no. 29 (2018): 1653–57. http://dx.doi.org/10.1557/adv.2018.95.
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ABSTRACTFlexible sensors are fundamental components of flexible electronics allowing a great number of applications from compliant robots to biomonitoring devices. The present work developed a carbohydrate-based elastomer (CBE) which possesses flexibility and tunable properties to meet the requirements of several sensing applications. Specifically, CBE was engineered to have high elasticity and sensing capabilities to humidity, stress and strain, enabling possible applications for monitoring physiological and external mechanical stimuli. These sensing capabilities of CBE were also adjustable to meet the requirements of applications such as electronic skin and wearable electronics.
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Zou, Yongjiu, Alberto Libanori, Jing Xu, Ardo Nashalian, and Jun Chen. "Triboelectric Nanogenerator Enabled Smart Shoes for Wearable Electricity Generation." Research 2020 (November 9, 2020): 1–20. http://dx.doi.org/10.34133/2020/7158953.
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The parallel evolution of wearable electronics, artificial intelligence, and fifth-generation wireless technology has created a technological paradigm with the potential to change our lives profoundly. Despite this, addressing limitations linked to continuous, sustainable, and pervasive powering of wearable electronics remains a bottleneck to overcome in order to maximize the exponential benefit that these technologies can bring once synergized. A recent groundbreaking discovery has demonstrated that by using the coupling effect of contact electrification and electrostatic induction, triboelectric nanogenerators (TENGs) can efficiently convert irregular and low-frequency passive biomechanical energy from body movements into electrical energy, providing an infinite and sustainable power source for wearable electronics. A number of human motions have been exploited to properly and efficiently harness this energy potential, including human ambulation. Shoes are an indispensable component of daily wearing and can be leveraged as an excellent platform to exploit such kinetic energy. In this article, the latest representative achievements of TENG-based smart electricity-generating shoes are comprehensively reviewed. We summarize ways in which not only can biomechanical energy be scavenged via ambulatory motion, but also biomonitoring of health parameters via tracking of rhythm and strength of pace can be implemented to aid in theranostic fields. This work provides a systematical review of the rational structural design, practical applications, scenario analysis, and performance evaluation of TENG-based smart shoes for wearable electricity generation. In addition, the perspective for future development of smart electricity-generation shoes as a sustainable and pervasive energy solution towards the upcoming era of the Internet of Things is discussed.
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Ricci, Mariachiara, Giulia Di Lazzaro, Antonio Pisani, Simona Scalise, Mohammad Alwardat, Chiara Salimei, Franco Giannini, and Giovanni Saggio. "Wearable Electronics Assess the Effectiveness of Transcranial Direct Current Stimulation on Balance and Gait in Parkinson’s Disease Patients." Sensors 19, no. 24 (December 11, 2019): 5465. http://dx.doi.org/10.3390/s19245465.
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Currently, clinical evaluation represents the primary outcome measure in Parkinson’s disease (PD). However, clinical evaluation may underscore some subtle motor impairments, hidden from the visual inspection of examiners. Technology-based objective measures are more frequently utilized to assess motor performance and objectively measure motor dysfunction. Gait and balance impairments, frequent complications in later disease stages, are poorly responsive to classic dopamine-replacement therapy. Although recent findings suggest that transcranial direct current stimulation (tDCS) can have a role in improving motor skills, there is scarce evidence for this, especially considering the difficulty to objectively assess motor function. Therefore, we used wearable electronics to measure motor abilities, and further evaluated the gait and balance features of 10 PD patients, before and (three days and one month) after the tDCS. To assess patients’ abilities, we adopted six motor tasks, obtaining 72 meaningful motor features. According to the obtained results, wearable electronics demonstrated to be a valuable tool to measure the treatment response. Meanwhile the improvements from tDCS on gait and balance abilities of PD patients demonstrated to be generally partial and selective.
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WANG, Feng, Mami TANAKA, and Seiji CHONAN. "Development of a wearable mental stress evaluation system using PVDF film sensor." Journal of Advanced Science 18, no. 1/2 (2006): 170–73. http://dx.doi.org/10.2978/jsas.18.170.
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Jongyoon Choi, B. Ahmed, and R. Gutierrez-Osuna. "Development and Evaluation of an Ambulatory Stress Monitor Based on Wearable Sensors." IEEE Transactions on Information Technology in Biomedicine 16, no. 2 (March 2012): 279–86. http://dx.doi.org/10.1109/titb.2011.2169804.
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Patlar Akbulut, Fatma, Baris Ikitimur, and Aydin Akan. "Wearable sensor-based evaluation of psychosocial stress in patients with metabolic syndrome." Artificial Intelligence in Medicine 104 (April 2020): 101824. http://dx.doi.org/10.1016/j.artmed.2020.101824.
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Lee, Yeongjun, Jong Won Chung, Gae Hwang Lee, Hyunbum Kang, Joo-Young Kim, Chisung Bae, Hyunjun Yoo, et al. "Standalone real-time health monitoring patch based on a stretchable organic optoelectronic system." Science Advances 7, no. 23 (June 2021): eabg9180. http://dx.doi.org/10.1126/sciadv.abg9180.
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Skin-like health care patches (SHPs) are next-generation health care gadgets that will enable seamless monitoring of biological signals in daily life. Skin-conformable sensors and a stretchable display are critical for the development of standalone SHPs that provide real-time information while alleviating privacy concerns related to wireless data transmission. However, the production of stretchable wearable displays with sufficient pixels to display this information remains challenging. Here, we report a standalone organic SHP that provides real-time heart rate information. The 15-μm-thick SHP comprises a stretchable organic light-emitting diode display and stretchable organic photoplethysmography (PPG) heart rate sensor on all-elastomer substrate and operates stably under 30% strain using a combination of stress relief layers and deformable micro-cracked interconnects that reduce the mechanical stress on the active optoelectronic components. This approach provides a rational strategy for high-resolution stretchable displays, enabling the production of ideal platforms for next-generation wearable health care electronics.
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Guk, Kyeonghye, Gaon Han, Jaewoo Lim, Keunwon Jeong, Taejoon Kang, Eun-Kyung Lim, and Juyeon Jung. "Evolution of Wearable Devices with Real-Time Disease Monitoring for Personalized Healthcare." Nanomaterials 9, no. 6 (May 29, 2019): 813. http://dx.doi.org/10.3390/nano9060813.
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Wearable devices are becoming widespread in a wide range of applications, from healthcare to biomedical monitoring systems, which enable continuous measurement of critical biomarkers for medical diagnostics, physiological health monitoring and evaluation. Especially as the elderly population grows globally, various chronic and acute diseases become increasingly important, and the medical industry is changing dramatically due to the need for point-of-care (POC) diagnosis and real-time monitoring of long-term health conditions. Wearable devices have evolved gradually in the form of accessories, integrated clothing, body attachments and body inserts. Over the past few decades, the tremendous development of electronics, biocompatible materials and nanomaterials has resulted in the development of implantable devices that enable the diagnosis and prognosis through small sensors and biomedical devices, and greatly improve the quality and efficacy of medical services. This article summarizes the wearable devices that have been developed to date, and provides a review of their clinical applications. We will also discuss the technical barriers and challenges in the development of wearable devices, and discuss future prospects on wearable biosensors for prevention, personalized medicine and real-time health monitoring.
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Lee, Jae Keun, Seung Ju Han, Kangil Kim, Yoon Hyuk Kim, and Sangmin Lee. "Wireless Epidermal Six-Axis Inertial Measurement Units for Real-Time Joint Angle Estimation." Applied Sciences 10, no. 7 (March 26, 2020): 2240. http://dx.doi.org/10.3390/app10072240.
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Technological advances in wireless communications, miniaturized sensors, and low-power electronics have made it possible to implement integrated wireless body area networks (WBANs). These developments enable the applications of wireless wearable systems for diagnosis, health monitoring, rehabilitation, and dependency care. Across the current range of commercial wearable devices, the products are not firmly fixed to the human body. To minimize data error caused by movement of the human body and to achieve accurate measurements, it is essential to bring the wearable device close to the skin. This paper presents the implementation of a patch-type, six-axis inertial measurement unit (IMU) with wireless communication technology. The device comprises hard-electronic components on a stretchable elastic substrate for application in epidermal electronics, to collect precise data from the human body. Instead of the commonly used cleanroom processes of implementing devices on a stretchable substrate, a simple and inexpensive “cut-solder-paste” method is adopted to fabricate complex, convoluted interconnections. Thus, the signal distortions in the proposed device can be minimized during various physical activities and skin deformations when used in gait analysis. The inertial sensor data measured from the motion of the body can be sent in real-time via Bluetooth to any processing unit enabled with such a widespread standard wireless interface. For performance evaluation, the implemented device is mounted on a rotation plate in order to compare performance with the conventional product. In addition, an experiment on joint angle estimation is performed by attaching the device to an actual human body. The preliminary results of the device indicate the potential to monitor people in remote settings for applications in mobile health, human-computer interfaces (HCIs), and wearable robots.
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Hao, Tian, Jeffrey Rogers, Hung-Yang Chang, Marion Ball, Kimberly Walter, Si Sun, Ching-Hua Chen, and Xinxin Zhu. "Towards Precision Stress Management: Design and Evaluation of a Practical Wearable Sensing System for Monitoring Everyday Stress." Iproceedings 3, no. 1 (September 22, 2017): e15. http://dx.doi.org/10.2196/iproc.8441.
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Lee, Myoungwoo, Hyun-Oh Kim, Jin-Hyo Boo, and Youn-Jea Kim. "Thermo-mechanical characteristics of the stretchable serpentine-patterned microelectrode." Functional Materials Letters 11, no. 03 (June 2018): 1850054. http://dx.doi.org/10.1142/s1793604718500546.
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Stretchable microelectrode is applied in various fields, such as sensory skins for soft robotics and wearable electronics for biomedical patches, etc. The structural quality of the stretchable microelectrode is a significant factor since it influences the thermo-mechanical characteristics. In order to improve the structural quality of the electrode, a serpentine-patterned configuration with various curvature angles of 60[Formula: see text], 90[Formula: see text] and 120[Formula: see text] were applied to the film of each electrode. In addition, thermal stress was applied at certain voltages to demonstrate the thermo-mechanical characteristics of the serpentine-patterned microelectrode. The numerical analysis on von Mises stress and thermal stress of the electrode was conducted with a commercial code, COMSOL Multiphysics ver. 5.3a. The results were graphically described by showing stress distributions of each case and the microelectrode having highest thermo-mechanical characteristics was derived.
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Leape, Charlotte, Allan Fong, and Raj M. Ratwani. "Heuristic Usability Evaluation of Wearable Mental State Monitoring Sensors for Healthcare Environments." Proceedings of the Human Factors and Ergonomics Society Annual Meeting 60, no. 1 (September 2016): 583–87. http://dx.doi.org/10.1177/1541931213601134.
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In recent years, there has been tremendous growth in both the number and diversity of wearable sensors, including sensors for monitoring mental state. Understanding physiological metrics such as fatigue and stress is an important aspect of human factors research, yet collecting and analyzing these measures can be resource intensive. This paper explores the usability and applicability of four off-the-shelf wearable sensors (Emotiv Epoc, Melon Headband, Spire Stone, and Muse™ Headband) for applied healthcare research. We perform a heuristic usability evaluation of the four sensors and discuss the extent to which each device can be applied to human factors healthcare research in clinical settings.
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Seoane, Fernando, Azadeh Soroudi, Ke Lu, David Nilsson, Marie Nilsson, Farhad Abtahi, and Mikael Skrifvars. "Textile-Friendly Interconnection between Wearable Measurement Instrumentation and Sensorized Garments—Initial Performance Evaluation for Electrocardiogram Recordings." Sensors 19, no. 20 (October 12, 2019): 4426. http://dx.doi.org/10.3390/s19204426.
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The interconnection between hard electronics and soft textiles remains a noteworthy challenge in regard to the mass production of textile–electronic integrated products such as sensorized garments. The current solutions for this challenge usually have problems with size, flexibility, cost, or complexity of assembly. In this paper, we present a solution with a stretchable and conductive carbon nanotube (CNT)-based paste for screen printing on a textile substrate to produce interconnectors between electronic instrumentation and a sensorized garment. The prototype connectors were evaluated via electrocardiogram (ECG) recordings using a sensorized textile with integrated textile electrodes. The ECG recordings obtained using the connectors were evaluated for signal quality and heart rate detection performance in comparison to ECG recordings obtained with standard pre-gelled Ag/AgCl electrodes and direct cable connection to the ECG amplifier. The results suggest that the ECG recordings obtained with the CNT paste connector are of equivalent quality to those recorded using a silver paste connector or a direct cable and are suitable for the purpose of heart rate detection.
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Adusei, Paa Kwasi, Kevin Johnson, Sathya N. Kanakaraj, Guangqi Zhang, Yanbo Fang, Yu-Yun Hsieh, Mahnoosh Khosravifar, Seyram Gbordzoe, Matthew Nichols, and Vesselin Shanov. "Asymmetric Fiber Supercapacitors Based on a FeC2O4/FeOOH-CNT Hybrid Material." C 7, no. 3 (August 14, 2021): 62. http://dx.doi.org/10.3390/c7030062.
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The development of new flexible and lightweight electronics has increased the demand for compatible energy storage devices to power them. Carbon nanotube (CNT) fibers have long been known for their ability to be assembled into yarns, offering their integration into electronic devices. They are hindered, however, by their low intrinsic energy storage properties. Herein, we report a novel composite yarn, synthesized through solvothermal processes, that attained energy densities in the range between 0.17 µWh/cm2 and 3.06 µWh/cm2, and power densities between 0.26 mW/cm2 and 0.97 mW/cm2, when assembled in a supercapacitor with a PVDF-EMIMBF4 electrolyte. The created unique composition of iron oxalate + iron hydroxide + CNT as an anode worked well in synergy with the much-studied PANI + CNT cathode, resulting in a highly stable yarn energy storage device that maintained 96.76% of its energy density after 4000 cycles. This device showed no observable change in performance under stress/bend tests which makes it a viable candidate for powering wearable electronics.
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Tabaczyńska, Agnieszka, Anna Dąbrowska, and Marcin Słoma. "Printed Graphene, Nanotubes and Silver Electrodes Comparison for Textile and Structural Electronics Applications." Sensors 21, no. 12 (June 11, 2021): 4038. http://dx.doi.org/10.3390/s21124038.
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Due to the appearance of smart textiles and wearable electronics, the need for electro-conductive textiles and electro-conductive paths on textiles has become clear. In this article the results of a test of developed textile electro-conductive paths obtained by applying the method of screen printing pastes containing silver nanoparticles and carbon (graphene, nanotubes, graphite) are presented. Conducted research included analysis of the adhesion test, as well as evaluation of the surface resistance before and after the washing and bending cycles. Obtained results indicated that the samples with the content of carbon nanotubes 3% by weight in PMMA on substrate made of aramid fibers (surface mass of 260 g/m2) were characterized by the best adhesion and the best resistance to washing and bending cycles. Such electro-conductive paths have potential to be used in smart clothing applications.
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Carbonaro, Nicola, Pietro Cipresso, Alessandro Tognetti, Gaetano Anania, Danilo De Rossi, Federica Pallavicini, Andrea Gaggioli, and Giuseppe Riva. "Psychometric Assessment of Cardio-Respiratory Activity Using a Mobile Platform." International Journal of Handheld Computing Research 5, no. 1 (January 2014): 13–29. http://dx.doi.org/10.4018/ijhcr.2014010102.
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It is increasingly recognized that stress has negative effects on growing numbers of people. Stress assessment is a complex issue, but different studies have shown that monitoring user psychophysiological parameter during daily life can be greatly helpful in stress evaluation. In this context, the European Collaborative Project INTERSTRESS is aimed at designing and developing advanced simulation and sensing technologies for the assessment and treatment of psychological stress, based on mobile biosensors.In this study a wearable biosensor platform able to collect physiological and behavioral parameters is reported. The developed mobile platform, in terms of hardware and processing algorithms, is described. Moreover the use of this wearable biosensor platform in combination with advanced simulation technologies, such as virtual reality, offer interesting opportunities for innovative personal health-care solutions to stress.
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Lee, Yongkuk, Connor Howe, Saswat Mishra, Dong Sup Lee, Musa Mahmood, Matthew Piper, Youngbin Kim, et al. "Wireless, intraoral hybrid electronics for real-time quantification of sodium intake toward hypertension management." Proceedings of the National Academy of Sciences 115, no. 21 (May 7, 2018): 5377–82. http://dx.doi.org/10.1073/pnas.1719573115.
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Recent wearable devices offer portable monitoring of biopotentials, heart rate, or physical activity, allowing for active management of human health and wellness. Such systems can be inserted in the oral cavity for measuring food intake in regard to controlling eating behavior, directly related to diseases such as hypertension, diabetes, and obesity. However, existing devices using plastic circuit boards and rigid sensors are not ideal for oral insertion. A user-comfortable system for the oral cavity requires an ultrathin, low-profile, and soft electronic platform along with miniaturized sensors. Here, we introduce a stretchable hybrid electronic system that has an exceptionally small form factor, enabling a long-range wireless monitoring of sodium intake. Computational study of flexible mechanics and soft materials provides fundamental aspects of key design factors for a tissue-friendly configuration, incorporating a stretchable circuit and sensor. Analytical calculation and experimental study enables reliable wireless circuitry that accommodates dynamic mechanical stress. Systematic in vitro modeling characterizes the functionality of a sodium sensor in the electronics. In vivo demonstration with human subjects captures the device feasibility for real-time quantification of sodium intake, which can be used to manage hypertension.
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Green, Ronald, Aderinto Ogunniyi, Dimeji Ibitayo, Gail Koebke, Mark Morgenstern, Aivars J. Lelis, Corey Dickens, and Brett A. Hull. "Evaluation of 4H–SiC DMOSFETs for High–Power Electronics Applications." Materials Science Forum 600-603 (September 2008): 1135–38. http://dx.doi.org/10.4028/www.scientific.net/msf.600-603.1135.
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In this paper, large area (0.18cm2) SiC DMOSFETs with 1.2 kV and 20 A rating are evaluated for power electronic switching applications. A drain-to-source voltage drop VDS of 2 V at a forward drain current of 20 A (JD = 110 A/cm2) was obtained and a specific on-resistance of 18 mΩ-cm2 was extracted at room temperature. The device on-resistance was measured up to 150°C and initially decreases with increasing temperature, but remains relatively flat over the entire temperature range, demonstrating stable device behavior. High voltage blocking of 1.2 kV between 25°C and 150°C is also demonstrated with a gate-to-source voltage VGS = 0 V. The drain leakage current under reverse bias and high temperature stress is shown to increase from 10 μA at 25°C to 27 μA at 150°C while maintaining the full blocking rating of the device. Experimental results from double-pulse clamped inductive load tests are presented demonstrating fast high voltage and high current switching capability. High voltage resistive-switching measurements on parallel connected SiC DMOSFETs were performed with VDS having rise and fall times of 49 and 74 ns respectively. Thermal camera images taken of parallel connected DMOSFET die during repetitive switching operation with VDS = 420 V, IDS = 25 A and a 40% duty cycle shows a 2°C difference in die temperature, which suggests even current sharing and temperature stable device operation.
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Lotfabadi, Ramtin, Joshua A. Granek, Jiayuan He, Ning Jiang, Fan He, Junhan Bae, Hamid Boland, and Catherine M. Burns. "Effect of Guided Tactical Breathing with Biofeedback on Acute Stress Attenuation and Marksmanship Performance of Novice Shooters." Proceedings of the Human Factors and Ergonomics Society Annual Meeting 64, no. 1 (December 2020): 641–45. http://dx.doi.org/10.1177/1071181320641146.
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The current study introduced a novel approach to inducing stress, and examining effects of wearable and mobile technology-assisted tactical breathing with real-time heartrate biofeedback, on the attenuation of acute stress, post-stressor recovery and performance. 39 participants with no prior experience with firearms participated in a marksmanship task engaging stationary targets with a semi-automatic rifle, at a controlled indoor shooting range. Novice shooters applying guided tactical breathing with biofeedback following exposure to the shooting task, were able to maintain lower arousal (uninhibited parasympathetic system). Findings suggested significant effect of intervention with biofeedback on stress attenuation, however no significant improvement of marksmanship performance among novice shooters resulting from the intervention was found. This study provides insights into app-led tactical breathing training to control arousal levels during stress, recommending strategies on further evaluation of the effectiveness of mobile and wearable technologies on stress attenuation for varying levels of marksmanship skill and individual difference.
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Chen, Dongzhen, Tongshan Chen, Yang Li, Shengxu Li, Liang Zhang, Yanwei Ren, Yaowu Wang, et al. "A Flexible Sensor Based on 3D Gold@Carbonaceous Nanohybrid with Defect Sites of Conductivity for the Wearable Sensing at Low Stress." Nano 16, no. 04 (March 25, 2021): 2150044. http://dx.doi.org/10.1142/s1793292021500442.
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The detection of subtle strain on the human body by flexible sensors suffers from the inferior sensitivity. In general, poor sensitivity derives from the intact structural integrity of building blocks of electric material. Inspired by the rolling friction in daily life, a three-dimensional (3D) nanohybrid of gold@carbonaceous nanoballs (Au@CBs) is developed. Compared with the pure Au nanostructure, the CBs increase the defect sites of conductivity and deformation sensitivity between Au nanostructures. The Flexible Stress Sensor (FSS) based on the 3D nanohybrid of Au@CBs is fabricated, and due to the enough displacement variation of 3D nanohybrid of Au@CBs, the change of resistance could be triggered by the tiny stress. The as-prepared sensor has high sensitivity at wide working range ([Formula: see text][Formula: see text]KPa[Formula: see text], 0.1–10[Formula: see text]KPa and [Formula: see text][Formula: see text]KPa[Formula: see text], 10–100[Formula: see text]KPa) and good cyclic stability (5000 cycles). Finally, the FSS based on the 3D nanohybrid of Au@CBs is employed for the detection of subtle vibration and movement of the human body, such as pulse and joint bending, which exerts great potential as wearable electronics.
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Convertino, Victor A., and Michael N. Sawka. "Wearable technology for compensatory reserve to sense hypovolemia." Journal of Applied Physiology 124, no. 2 (February 1, 2018): 442–51. http://dx.doi.org/10.1152/japplphysiol.00264.2017.
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Traditional monitoring technologies fail to provide accurate or early indications of hypovolemia-mediated extremis because physiological systems (as measured by vital signs) effectively compensate until circulatory failure occurs. Hypovolemia is the most life-threatening physiological condition associated with circulatory shock in hemorrhage or sepsis, and it impairs one’s ability to sustain physical exertion during heat stress. This review focuses on the physiology underlying the development of a novel noninvasive wearable technology that allows for real-time evaluation of the cardiovascular system’s ability to compensate to hypovolemia, or its compensatory reserve, which provides an individualized estimate of impending circulatory collapse. Compensatory reserve is assessed by real-time changes (sampled millions of times per second) in specific features (hundreds of features) of arterial waveform analog signals that can be obtained from photoplethysmography using machine learning and feature extraction techniques. Extensive experimental evidence employing acute reductions in central blood volume (using lower-body negative pressure, blood withdrawal, heat stress, dehydration) demonstrate that compensatory reserve provides the best indicator for early and accurate assessment for compromises in blood pressure, tissue perfusion, and oxygenation in resting human subjects. Engineering challenges exist for the development of a ruggedized wearable system that can measure signals from multiple sites, improve signal-to-noise ratios, be customized for use in austere conditions (e.g., battlefield, patient transport), and be worn during strenuous physical activity.
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Murugesan, M., Y. Susumago, K. Sumitani, Y. Imai, S. Kimura, and T. Fukushima. "Laue microdiffraction evaluation of bending stress in Au wiring formed on chip-embedded flexible hybrid electronics." Japanese Journal of Applied Physics 60, SB (February 25, 2021): SBBC02. http://dx.doi.org/10.35848/1347-4065/abdb81.
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Masood Khan, Khalid. "Adaptive wavelet packets for minimization of error in computation of mental stress." International Journal of Wavelets, Multiresolution and Information Processing 13, no. 05 (September 2015): 1550033. http://dx.doi.org/10.1142/s0219691315500332.
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This paper describes a study on evaluation of mental stress using adaptive wavelet packets filtering techniques. For mental stress to become chronic or if it remains for longer periods of time, then it can cause or trigger diseases such as hypertension, diabetes, insomnia, depression etc. There is a need for objective assessment of stress and develop counter conditions to relieve the body from stress. We have designed a wireless wearable sensor platform that can be used to capture a vast range of biomedical signals including heart rate, skin conductance and respiration rates. As stress is a reactionary phenomenon and its response vary from person to person, so an adaptive wavelet filtering packet is proposed to minimize intra subjective variations. The filtering technique has two folded effects; it reduces the classification error and it provides tuning to adapt it to users requirements. The wearable sensor platform is based on ease of use and a subject can be monitored for days and changes in his/her physiological conditions are recorded. The main advantage in monitoring stress is that if required in needs than necessary actions can be taken to remove stressful conditions.
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Dąbrowska, Anna, Grażyna Bartkowiak, and Rafał Kotas. "Evaluation of Functionality of Warning System in Smart Protective Clothing for Firefighters." Sensors 21, no. 5 (March 4, 2021): 1767. http://dx.doi.org/10.3390/s21051767.
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Recent achievements in the field of miniaturization of electronics have led to a significant interest in its application into the protective clothing for firefighters in order to improve their safety and health. However, up to now there are not any requirements and standardized test methods enabling confirmation of safety of use and functionality of these systems in work environment. In the paper, an importance of evaluation of such smart wearable system in predicted utility conditions is highlighted. Three variants of the specially developed personal warning systems (PWSs) for integration with either health status or environmental sensors to be used in smart protective clothing for firefighters are presented, i.e., with LCD display, LED diodes and vibrating element. For the purpose of evaluation a new testing methodology was developed. The PWSs were evaluated on a basis of perception of warning signals by firefighters in simulated utility conditions including temperature, light, noise, fog and performed activities. In the case of marching, even 75% of signals generated by PWS with LCD display were not received. Physical activity did not influence on functionality of PWS with vibrating element. For the PWS with LED diodes, the signal was received statistically significantly quicker than in the case of other PWS and the mean value of voice response time was below 3 s.
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Paletta, Lucas, Harald Ganster, Michael Schneeberger, Martin Pszeida, Gerald Lodron, Katrin Pechstädt, Michaela Spitzer, and Christiane Reischl. "Towards Large-Scale Evaluation of Mental Stress and Biomechanical Strain in Manufacturing Environments Using 3D-Referenced Gaze and Wearable-based Analytics." Electronic Imaging 2021, no. 6 (January 18, 2021): 310–1. http://dx.doi.org/10.2352/issn.2470-1173.2021.6.iriacv-310.
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In future manufacturing human-machine interaction will evolve towards flexible and smart collaboration. It will meet requirements from the optimization of assembly processes as well as from motivated and skilled human behavior. Recently, human factors engineering has substantially progressed by means of detailed task analysis. However, there is still a lack in precise measuring cognitive and sensorimotor patterns for the analysis of long-term mental and physical strain. This work presents a novel methodology that enables real-time measurement of cognitive load based on executive function analyses as well as biomechanical strain from non-obtrusive wearable sensors. The methodology works on 3D information recovery of the working cell using a precise stereo measurement device. The worker is equipped with eye tracking glasses and a set of wearable accelerometers. Wireless connectivity transmits the sensor-based data to a nearby PC for monitoring. Data analytics then recovers the 3D geometry of gaze and viewing frustum within the working cell and furthermore extracts the worker's task switching rate as well as a skeleton-based approximation of worker's posture associated with an estimation of biomechanical strain of muscles and joints. First results enhanced by AI-based estimators demonstrate a good match with the results of an activity analysis performed by occupational therapists.
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SHUR, MICHAEL S., SERGEY L. RUMYANTSEV, and REMIS GASKA. "SEMICONDUCTOR THIN FILMS AND THIN FILM DEVICES FOR ELECTROTEXTILES." International Journal of High Speed Electronics and Systems 12, no. 02 (June 2002): 371–90. http://dx.doi.org/10.1142/s0129156402001320.
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We discuss the evolution from wearable electronics and conductive textiles to electrotextiles with embedded semiconducting films and semiconductor devices and review different semiconductor technologies competing for applications in electrotextiles. We also report on fabrication, characterization, and properties of nanocrystalline semiconductor and metal films and thin-film device structures chemically deposited on fibers, cloth, and large area flexible substrates at low temperatures (close to room temperature). Our approach is based on a new process of depositing polycrystalline CdSe (1.75 eV), CdS (2.4 eV), PbS (0.4 eV), PbSe (0.24 eV) and CuxS (semiconductor/metal) films on flexible substrates from the water solutions of complex-salt compounds. We have covered areas up to 8 × 10 inches but the process can be scaled up. The film properties are strongly affected by processing. We fabricated a lateral solar cell with alternating Cu2-xS and nickel contact stripes deposited on top of a view foil. These sets of contacts represented "ohmic" and "non-ohmic" contacts, respectively. Then CdS films of approximately 0.5 μm thick were deposited on top. We also fabricated a "sandwich" type photovoltaic cell, where the CdS film was sandwiched between an In2O3 layer deposited on a view foil and a Cu2-xS layer deposited on top. Both structures exhibited transient response under light, with the characteristic response time decreasing with the illumination wavelength. This is consistent with having deeper localized states in the energy gap determining the transients for shorter wavelength radiation. (Slow transients related to trapping effects are typical for polycrystalline CdS materials.) We also report on the photovoltaic effect in CdS/CuS films deposited on trylene threads and on a field effect in these films deposited on a flexible copper wire. CdS films deposited on viewfoils exhibit unique behavior under stress and UV radiation exposure with reproducible resistance changes of several orders of magnitude with bending up to 10 mm curvature. Our results clearly demonstrate the feasibility of using this technology for photovoltaic and microelectronics applications for electrotextiles and wearable electronics applications.
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Jiang, Chen, Hanbin Ma, and Arokia Nathan. "Stability Analysis of All-Inkjet-Printed Organic Thin-Film Transistors." MRS Advances 3, no. 33 (2018): 1871–76. http://dx.doi.org/10.1557/adv.2018.25.
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Abstract:All-inkjet-printed organic thin-film transistors take advantage of low-cost fabrication and high compatibility to large-area manufacturing, making them potential candidates for flexible, wearable electronics. However, in real-world applications, device instability is an obstacle, and thus, understanding the factors that cause instability becomes compelling. In this work, all-inkjet-printed low-voltage organic thin-film transistors were fabricated and their stability was investigated. The devices demonstrate low operating voltage (<3 V), small subthreshold slope (128 mV/decade), good mobility (0.1 cm2 V−1 s−1), close-to-zero threshold voltage (−0.16 V), and high on/off ratio (>105). Several aspects of stability were investigated, including mechanical bending, shelf life, and bias stress. Based on these tests, we find that water molecule polarization in dielectrics is the main factor causing instability. Our study suggests use of a printable water-resistant dielectric for stability enhancement for the future development of all-inkjet-printed organic thin-film transistors.
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Sarwar, Ferdous, and Val R. Marinov. "Reliability of Embedded Ultrathin Chips Subjected to Cyclic Stresses." Journal of Microelectronics and Electronic Packaging 9, no. 2 (April 1, 2012): 104–11. http://dx.doi.org/10.4071/imaps.330.
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Recently, ultra-thin embedded die technology has garnered much attention for its ability to produce assemblies in two or three dimensions with reduced footprint, low profile, low weight, and conformity. The embedded die technology can be successfully utilized in the development of flexible printed circuits to satisfy the demand for reliable and high density packaging solutions. With tremendous application potential in wearable and disposable electronics, the reliability of the flexible embedded die package is of paramount importance. Presented are results from the experimental study on the electrical performance of ultrathin (≤50 μm) silicon dice embedded into a polymer substrate and bumped using three different techniques—electroplating, wire bonding, and sputtering. The reliability of different packages was evaluated through a series of thermal and mechanical cyclic stress tests. The results suggested that the reliability of all embedded dice was high regardless of the bumping technology. However, compared with the other two methods, wire bonded stud bumps provided better and more consistent performance.
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Ganti, Venu, Andrew M. Carek, Hewon Jung, Adith V. Srivatsa, Deborah Cherry, Levather Neicey Johnson, and Omer T. Inan. "Enabling Wearable Pulse Transit Time-Based Blood Pressure Estimation for Medically Underserved Areas and Health Equity: Comprehensive Evaluation Study." JMIR mHealth and uHealth 9, no. 8 (August 2, 2021): e27466. http://dx.doi.org/10.2196/27466.
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Background Noninvasive and cuffless approaches to monitor blood pressure (BP), in light of their convenience and accuracy, have paved the way toward remote screening and management of hypertension. However, existing noninvasive methodologies, which operate on mechanical, electrical, and optical sensing modalities, have not been thoroughly evaluated in demographically and racially diverse populations. Thus, the potential accuracy of these technologies in populations where they could have the greatest impact has not been sufficiently addressed. This presents challenges in clinical translation due to concerns about perpetuating existing health disparities. Objective In this paper, we aim to present findings on the feasibility of a cuffless, wrist-worn, pulse transit time (PTT)–based device for monitoring BP in a diverse population. Methods We recruited a diverse population through a collaborative effort with a nonprofit organization working with medically underserved areas in Georgia. We used our custom, multimodal, wrist-worn device to measure the PTT through seismocardiography, as the proximal timing reference, and photoplethysmography, as the distal timing reference. In addition, we created a novel data-driven beat-selection algorithm to reduce noise and improve the robustness of the method. We compared the wearable PTT measurements with those from a finger-cuff continuous BP device over the course of several perturbations used to modulate BP. Results Our PTT-based wrist-worn device accurately monitored diastolic blood pressure (DBP) and mean arterial pressure (MAP) in a diverse population (N=44 participants) with a mean absolute difference of 2.90 mm Hg and 3.39 mm Hg for DBP and MAP, respectively, after calibration. Meanwhile, the mean absolute difference of our systolic BP estimation was 5.36 mm Hg, a grade B classification based on the Institute for Electronics and Electrical Engineers standard. We have further demonstrated the ability of our device to capture the commonly observed demographic differences in underlying arterial stiffness. Conclusions Accurate DBP and MAP estimation, along with grade B systolic BP estimation, using a convenient wearable device can empower users and facilitate remote BP monitoring in medically underserved areas, thus providing widespread hypertension screening and management for health equity.
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Ibanez-Labiano, Isidoro, and Akram Alomainy. "Dielectric Characterization of Non-Conductive Fabrics for Temperature Sensing through Resonating Antenna Structures." Materials 13, no. 6 (March 11, 2020): 1271. http://dx.doi.org/10.3390/ma13061271.
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Seamless integration of electronics within clothing is key for further development of efficient and convenient wearable technologies. Therefore, the characterization of textile and fabric materials under environmental changes and other parametric variations is an important requirement. To our knowledge, this paper presents for the first time the evaluation of dielectric characterization over temperature for non-conductive textiles using resonating structures. The paper describes the effects of temperature variations on the dielectric properties of non-conductive fabrics and how this can be derived from the performance effects of a simple microstrip patch antenna. Organic cotton was chosen as the main substrate for this research due to its broad presence in daily clothing. A dedicated measurement setup is developed to allow reliable and repeatable measurements, isolating the textile samples from external factors. This work shows an approximately linear relation between temperature and textile’s dielectric constant, giving to fabric-based antennas temperature sensing properties with capability up to 1 degree Celsius at millimeter-wave frequencies.
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Yokota, Tomoyuki, Peter Zalar, Martin Kaltenbrunner, Hiroaki Jinno, Naoji Matsuhisa, Hiroki Kitanosako, Yutaro Tachibana, Wakako Yukita, Mari Koizumi, and Takao Someya. "Ultraflexible organic photonic skin." Science Advances 2, no. 4 (April 2016): e1501856. http://dx.doi.org/10.1126/sciadv.1501856.
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Thin-film electronics intimately laminated onto the skin imperceptibly equip the human body with electronic components for health-monitoring and information technologies. When electronic devices are worn, the mechanical flexibility and/or stretchability of thin-film devices helps to minimize the stress and discomfort associated with wear because of their conformability and softness. For industrial applications, it is important to fabricate wearable devices using processing methods that maximize throughput and minimize cost. We demonstrate ultraflexible and conformable three-color, highly efficient polymer light-emitting diodes (PLEDs) and organic photodetectors (OPDs) to realize optoelectronic skins (oe-skins) that introduce multiple electronic functionalities such as sensing and displays on the surface of human skin. The total thickness of the devices, including the substrate and encapsulation layer, is only 3 μm, which is one order of magnitude thinner than the epidermal layer of human skin. By integrating green and red PLEDs with OPDs, we fabricate an ultraflexible reflective pulse oximeter. The device unobtrusively measures the oxygen concentration of blood when laminated on a finger. On-skin seven-segment digital displays and color indicators can visualize data directly on the body.
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Godignon, Phillippe, Silvia Massetti, X. Jordà, V. Soler, J. Moreno, D. Lopez, and E. Maset. "SiC Power Switches Evaluation for Space Applications Requirements." Materials Science Forum 858 (May 2016): 852–55. http://dx.doi.org/10.4028/www.scientific.net/msf.858.852.
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We have evaluated several SiC power switches available on the market, by defining and performing a global test campaign oriented to Space applications requirements, in order to define their main benefits but also the limits of current SiC technology. This allowed to identify a number of target applications where SiC could be used as a technology push for a new generation of space electronics units. Silicon devices qualified for space systems above 600V for the switches and 1200V for the rectifiers are not available due to performances limitations of Si. Among the typical static and dynamic characterization, we have performed temperature and power stress and HTRB tests. More remarkably, we have carried out a first batch of total dose and heavy ions radiation experiments on 3 types of power switches: normally-on JFET, normally-off JFET and power MOSFET. Due to its higher stability and radiation hardness, the normally-on JFET is today the more adequate and reliable switch for the space applications.
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Dr. P. Prabhavathy, Nagalakshmi Vallabhaneni,. "The Analysis of the Impact of Yoga on Healthcare and Conventional Strategies for Human Pose Recognition." Turkish Journal of Computer and Mathematics Education (TURCOMAT) 12, no. 6 (April 5, 2021): 1772–83. http://dx.doi.org/10.17762/turcomat.v12i6.4032.
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Human pose estimation is a profound, established computer vision issue that has uncovered numerous past difficulties. Breaking down human exercise is advantageous in multiple fields like surveillance, biometrics, and many healthcare applications. Workout with yoga poses is famous these days since yoga activities can expand adaptability and muscular quality, and the respiration procedure will be improvised. The yoga postures evaluation is hard to check, so specialists will most likely be unable to benefit from the exercises ultimately. IoT-based yoga frameworks are required for individuals who need to rehearse Yoga at home. A few studies are recommended camera-oriented or wearable gadget-oriented yoga posture finding strategies with more precision. Nonetheless, camera-based plans have security and privacy issues, and the wearable device-based methods are illogical in the earlier applications. To build such systems, one must have a strong foundation and current research in pose estimation. In this paper, first, the impact of Yoga on humans with various stress levels is analysed on the real-time data. Second, the comprehensive review of yoga posture recognition systems from machine learning to deep learning strategies and evaluation metrics discussed
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Florkowski, Marek, Barbara Florkowska, and Pawel Zydron. "Partial Discharges in Insulating Systems of Low Voltage Electric Motors Fed by Power Electronics—Twisted-Pair Samples Evaluation." Energies 12, no. 5 (February 26, 2019): 768. http://dx.doi.org/10.3390/en12050768.
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Power electronics switching devices currently represent the dominant technology for supplying low voltage (LV) electric motors. The fast switching processes exert a different class of stress on dielectric insulating materials than standard sinusoidal excitations. Such stresses result in an increase in the dynamic activity of the working electric field, which in turn lead to an increased likelihood of partial discharges (PD). The stator design of low voltage motor is often in form of random-wound windings, where the magnet wires (copper or aluminum round wires coated with thin layer of insulation) form a common system of coils with not precisely defined mutual position of particular turns, resulting in various turn-to-turn and coil-to-coil voltage distributions. Pulse Width Modulated (PWM) voltage waveforms from modern electronic inverters are characterized by very short rise times and presence of repetitively occurring overvoltages that can significantly stress the insulation of feeding cables and motors. These factors influence the inception and dynamics of PD and processes of space charge accumulation in electrical insulation. In this paper investigations performed on round magnet wire twisted-pair samples representing LV motor random-wound winding elements are presented. Special attention was afforded to the twist configurations, observed breakdown voltage and PD activity. To describe the field conditions for the formation of PD in the turn-to-turn insulation system, the results of numerical simulations of electric field distributions for winding wires with different diameters, modeled using the COMSOL program, were analyzed. PD created in the insulating systems of model twisted-pair systems were registered and analyzed using the phase resolved partial discharge analysis (PRPDA) method.
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Dikariyanto, Vita, Leanne Smith, May Robertson, Eslem Kusaslan, Molly O'Callaghan-Latham, Philip Chowienczyk, Sarah Berry, and Wendy Hall. "Effects of Daily Intake of Almonds on Cardiac Autonomic Functions Measured by Heart Rate Variability in Response to Acute Stress: A Randomized Controlled Trial." Current Developments in Nutrition 4, Supplement_2 (May 29, 2020): 20. http://dx.doi.org/10.1093/cdn/nzaa040_020.
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Abstract Objectives Stress is inversely associated with heart rate variability (HRV), an indicator of cardiac autonomic function and a predictor of risk of sudden cardiac death. At times of stress, people tend to favor high sugar and fatty foods, often as snacks, with potential adverse effects on cardiometabolic health. Dietary recommendations for cardiovascular disease (CVD) prevention emphasize fruits, vegetables, wholegrains and nuts. There is evidence that consumption of nuts can reduce LDL cholesterol and blood pressure and help with weight management, however the impact of nuts on HRV in response to stress is unknown. The ATTIS dietary intervention study investigated the HRV response to acute stress following 6-week substitution of almonds for typical snacks high in refined starch, free sugars and saturated fats, and low in fibre. The study population comprised adults aged 30–70 y, who were habitual snack consumers, and at moderate risk of developing CVD. It was hypothesized that snacking on almonds would increase HRV during stress tasks, when HRV is expected to be reduced due to increased sympathetic activity. Methods A 6-week randomized controlled parallel trial was conducted. Participants were randomized to 1) control snacks (mini-muffins formulated to follow the average UK snack nutrient profile), or 2) dry-roasted whole almonds, both providing 20% estimated energy requirement. Supine HRV was measured (Mega Electronics Emotion Faros 180°, 2-leads wearable ECG-HRV monitor) during resting (5 min), physical stress (blood pressure monitor cuff inflation 200 mmHg, 5 min) and mental stress (Stroop colour-word test, 5 min) tasks pre- and post-intervention. A total of 105 participants (73 females and 32 males; mean age 56.2 y, SD 10.4) completed the trial. Results Almonds significantly increased the beat-to-beat HRV parameter, high-frequency power, during the mental stress test (mean difference 124 ms2; 95% CI 11, 237; P = 0.031) relative to control, indicating increased parasympathetic regulation. There were no treatment effects during resting and the physical stress task. Conclusions Snacking on whole almonds as a replacement for typical snacks increases HRV during mental stress, indicating an increased resilience in cardiac autonomic function and a novel mechanism whereby nuts may be cardioprotective. Funding Sources Almond Board of California.
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Bartlett, Michael D., Navid Kazem, Matthew J. Powell-Palm, Xiaonan Huang, Wenhuan Sun, Jonathan A. Malen, and Carmel Majidi. "High thermal conductivity in soft elastomers with elongated liquid metal inclusions." Proceedings of the National Academy of Sciences 114, no. 9 (February 13, 2017): 2143–48. http://dx.doi.org/10.1073/pnas.1616377114.
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Soft dielectric materials typically exhibit poor heat transfer properties due to the dynamics of phonon transport, which constrain thermal conductivity (k) to decrease monotonically with decreasing elastic modulus (E). This thermal−mechanical trade-off is limiting for wearable computing, soft robotics, and other emerging applications that require materials with both high thermal conductivity and low mechanical stiffness. Here, we overcome this constraint with an electrically insulating composite that exhibits an unprecedented combination of metal-like thermal conductivity, an elastic compliance similar to soft biological tissue (Young’s modulus < 100 kPa), and the capability to undergo extreme deformations (>600% strain). By incorporating liquid metal (LM) microdroplets into a soft elastomer, we achieve a ∼25× increase in thermal conductivity (4.7 ± 0.2 W⋅m−1⋅K−1) over the base polymer (0.20 ± 0.01 W⋅m−1·K−1) under stress-free conditions and a ∼50× increase (9.8 ± 0.8 W⋅m−1·K−1) when strained. This exceptional combination of thermal and mechanical properties is enabled by a unique thermal−mechanical coupling that exploits the deformability of the LM inclusions to create thermally conductive pathways in situ. Moreover, these materials offer possibilities for passive heat exchange in stretchable electronics and bioinspired robotics, which we demonstrate through the rapid heat dissipation of an elastomer-mounted extreme high-power LED lamp and a swimming soft robot.