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Asl, Sara Nazari, Frank Ludwig i Meinhard Schilling. "Noise properties of textile, capacitive EEG electrodes". Current Directions in Biomedical Engineering 1, nr 1 (1.09.2015): 34–37. http://dx.doi.org/10.1515/cdbme-2015-0009.
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AbstractThe rigid surface of the conventional PCB-based capacitive electrode produces an undefined distance between the skin and the electrode surface. Therefore, the capacitance introduced by them is uncertain and can vary from electrode to electrode due to their different positions on the scalp. However, textile electrodes which use conductive fabric as electrode surfaces, are bendable over the scalp. Therefore, it provides a certain value of the capacitance which is predictable and calculable accurately if the effective distance to the scalp surface can be determined. In this paper noise characteristics of textile electrodes with different fabric sizes as electrode’s surface and capacity calculations related to each size are presented to determine the effective distances for each electrode size.
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Wang, Li, Yun Zhou, Jie Wang i Ning Hu. "Approaching Capacitive Deionization (CDI) on Desalination of Water and Wastewater - New Progress and its Potential". Advanced Materials Research 1088 (luty 2015): 557–61. http://dx.doi.org/10.4028/www.scientific.net/amr.1088.557.
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Capacitive deionization (CDI) technology is a challenge on an economical and effective electrosorption desalination method. The paper analyses the CDI current status and progress of carbon electrode materials, and describes the types of CDI and its performances of testing materials. The electrosorption capacities are summarized on the carbon electrode materials and the current hurdles. The reported numbers from the literature vary in a wide range between 0.25 and 26.42 mg/g of both electrodes CDI cell, we suggest that the CDI electrodes should have an adsorption of at least 9.0 mg/g NaCl when the applyed voltage is 2.0 V. The potential capacitive deionization technologies are proposed here.
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Wang, Zhiyu, Shun Wang, Guangyou Fang i Qunying Zhang. "Investigation on a Novel Capacitive Electrode for Geophysical Surveys". Journal of Sensors 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/4209850.
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Nonpolarizable electrodes are applied widely in the electric field measurement for geophysical surveys. However, there are two major problems: (1) systematic errors caused by poor electrical contact in the high resistive terrains and (2) environmental damage associated with using nonpolarizable electrodes. A new alternative structure of capacitive electrode, which is capable of sensing surface potential through weak capacitive coupling, is presented to solve the above problems. A technique is introduced to neutralize distributed capacitance and input capacitance of the detection circuit. With the capacitance neutralization technique, the transmission coefficient of capacitive electrode remains stable when environmental conditions change. The simulation and field test results indicate that the new capacitive electrode has an operating bandwidth range from 0.1 Hz to 1 kHz. The capacitive electrodes have a good prospect of the applications in geophysical prospecting, especially in resistive terrains.
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Suen, Min-Sheng, i Rongshun Chen. "Capacitive Tactile Sensor with Concentric-Shape Electrodes for Three-Axial Force Measurement". Proceedings 2, nr 13 (19.12.2018): 708. http://dx.doi.org/10.3390/proceedings2130708.
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In this paper, a novel capacitive tactile sensing device has proposed and demonstrated to solve coupling problem within the normal force and shear force by the unique design of electrode shape. In addition, the tactile sensor was added in the measuring capability of torsion sensing compared with traditional capacitive sensor. The perceptive unit of tactile sensor, which was consist of five sensing electrodes to detect three-axial force. The complete tactile sensor composed of a top electrode, a bottom electrode, and a spacer layer. Each capacitive sensing unit comprised a pair of the concentric-shape but different size electrodes (top electrode and bottom electrode). In the future, the proposed tactile sensor can be utilized in the wearable devices, flexible interface, and bionic robotic skins.
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Tamura, Saki, Justin K. M. Wyss, Mirza Saquib Sarwar, Addie Bahi, John D. W. Madden i Frank K. Ko. "Woven Structure for Flexible Capacitive Pressure Sensors". MRS Advances 5, nr 18-19 (2020): 1029–37. http://dx.doi.org/10.1557/adv.2020.136.
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AbstractFlexible and stretchable capacitive pressure sensors have been developed in recent years due to their potential applications in health monitoring, robot skins, body activity measurements and so on. In order to enhance sensor sensitivity, researchers have changed structure of the dielectric of parallel plate capacitive sensor . Here we enhance the sensor sensitivities by changing electrode composition and explore the use of a woven electrode structure sensor with silver coated nylon yarn and EcoflexTM. The woven structure enhanced sensitivity 2.3 times relative to a simple cross-grid geometry (sensitivity was 0.003 kPa-1). Furthermore, it is also observed that the sensor with the woven electrode also had better repeatability and showed less creep than a device using carbon black electrodes. The woven structure of the electrodes enabled the device to be compliant, despite the presence of the stiff nylon fibres – thereby enabling good sensitivity without the creep seen in softer electrodes.
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Gao, X., A. Omosebi, Z. Ma, F. Zhu, J. Landon, M. Ghorbanian, N. Kern i K. Liu. "Capacitive deionization using symmetric carbon electrode pairs". Environmental Science: Water Research & Technology 5, nr 4 (2019): 660–71. http://dx.doi.org/10.1039/c8ew00957k.
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Laxman, Karthik, Laila Al Gharibi i Joydeep Dutta. "Capacitive deionization with asymmetric electrodes: Electrode capacitance vs electrode surface area". Electrochimica Acta 176 (wrzesień 2015): 420–25. http://dx.doi.org/10.1016/j.electacta.2015.07.036.
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Savchuk, Arsen. "Development of a model of electric impedance in the contact between the skin and a capacitive active electrode when measuring electrocardiogram in combustiology". Eastern-European Journal of Enterprise Technologies 2, nr 5 (110) (30.04.2021): 32–38. http://dx.doi.org/10.15587/1729-4061.2021.228735.
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Long-term ECG (electrocardiogram) measurement in patients with burns is a complicated problem since the overlapping of surface contact electrodes can lead to additional injuries. The possibility of ECG recording in patients with burns using capacitive electrodes was not proved, and there are no models of the electrode contact with a patient’s body while rehabilitation means are used. In this paper, the model of the contact between capacitive electrodes and the skin was modified and the circuit model of the contact: skin – bandages (saline solution) – film – active capacitive electrode, was described. The influence of the parameters of a capacitive electrode on the amplitude-frequency characteristics (AFC) of the contact of an electrode with skin was assessed. It was found that contact capacitance is crucial to obtain a high-quality ECG signal. The parameters of the impedance of bandages, saline solution, a dielectric film were calculated, and their effect on the AFC was studied. Based on the modified model, the AFC contact was modeled taking into consideration all the calculated parameters; it was found that the resulting AFC of the contact corresponds to the frequency range of the ECG signal. Analysis of the calculations proves the possibility of using capacitive electrodes when applying various rehabilitation means. It was found that at a change in the impedance of the saline solution from 0.1 gigaohms to 1 gigaohm, the changes in the AFC of the contact are not crucial for the final quality of the received signal. All calculations were carried out by modeling in the Qucs environment (ngspice SPICE). Simulation results can be used in the development of new types of capacitive electrocardiographic electrodes. The proposed model can be used to study other wound covers, as well as to model physiological processes when putting artificial skin and wound covers
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Tang, Yue, Ronghui Chang, Limin Zhang, Feng Yan, Haowen Ma i Xiaofeng Bu. "Electrode Humidification Design for Artifact Reduction in Capacitive ECG Measurements". Sensors 20, nr 12 (18.06.2020): 3449. http://dx.doi.org/10.3390/s20123449.
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For wearable capacitive electrocardiogram (ECG) acquisition, capacitive electrodes may cause severe motion artifacts due to the relatively large friction between the electrodes and the dielectrics. In some studies, water can effectively suppress motion artifacts, but these studies lack a complete analysis of how water can suppress motion artifacts. In this paper, the effect of water on charge decay of textile electrode is studied systematically, and an electrode controllable humidification design using ultrasonic atomization is proposed to suppress motion artifacts. Compared with the existing electrode humidification designs, the proposed electrode humidification design can be controlled by a program to suppress motion artifacts at different ambient humidity, and can be highly integrated for wearable application. Firstly, the charge decay mode of the textile electrode is given and it is found that the process of free water evaporation at an appropriate free water content can be the dominant way of triboelectric charge dissipation. Secondly, theoretical analysis and experiment verification both illustrate that water contained in electrodes can accelerate the decay of triboelectric charge through the free water evaporation path. Finally, a capacitive electrode controllable humidification design is proposed by applying integrated ultrasonic atomization to generate atomized drops and spray them onto textile electrodes to accelerate the decay of triboelectric charge and suppress motion artifacts. The performance of the proposed design is verified by the experiment results, which shows that the proposed design can effectively suppress motion artifacts and maintain the stability of signal quality at both low and high ambient humidity. The signal-to-noise ratio of the proposed design is 33.32 dB higher than that of the non-humidified design at 25% relative humidity and is 22.67 dB higher than that of non-humidified electrodes at 65% relative humidity.
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Park, Byoung-Nam. "Differential Analysis of Surface-Dominated vs. Bulk-Dominated Electrochemical Processes in Lithium Iron Phosphate Cathodes". Korean Journal of Metals and Materials 62, nr 8 (5.08.2024): 624–30. http://dx.doi.org/10.3365/kjmm.2024.62.8.624.
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We employed electrophoretic deposition (EPD) using AC voltage to prepare lithium iron phosphate (LFP) Li-ion battery electrodes with varying the LFP thickness, to compare bulk-limited electro chemical reaction with the surface-limited electrochemical reactions. We analyzed the electrochemical performances of the thin and thick LFP electrodes at various scan rates. They revealed that with increasing scan rates, both electrode types showed a greater reliance on surface capacitive effects for charge storage. Significantly, the thin LFP electrode predominantly exhibited capacitive charge storage, surpassing diffusion-based storage mechanisms. This was in contrast to the performance of the thicker electrode, which had a lower capacitive contribution. Quantitative assessment using the Randles-Sevcik equation further confirmed the superior performance of the thin LFP electrode. The Li-ion diffusion coefficient of the thin LFP electrode was substantially higher (9.6×10<sup>-9</sup> cm<sup>2</sup>·V<sup>-1</sup>·s<sup>-1</sup>) compared to the thick electrode (2.0×10<sup>-9</sup> cm<sup>2</sup>·V<sup>-1</sup>·s<sup>-1</sup>), indicating enhanced ionic mobility in the surface-limited electrochemical reaction. These findings emphasize the significant advantages of thinner LFP electrodes, and induced surface limited electrochemical reaction, in high-rate applications, including higher capacitive charge storage and more favorable ion diffusion characteristics. The advantages conferred by the enhanced capacitive charge storage and superior ion diffusion in thin LFP electrodes have profound implications for the design and optimization of next-generation high-rate batteries. By focusing on tailoring electrode thickness, we can harness the full potential of surface-limited reactions, pushing the boundaries of what is currently achievable in terms of power density, charging speed, and cycle life in LFP-based energy storage technologies. These enhancements align with the growing need for high-performing, reliable energy storage solutions in an increasingly electrified and energy-conscious world.
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Pohlman, Garrett, Andrew Haddad, Bilen Akuzum, Ertan Agar i Lukas Hackl. "Finite Element Analysis of Flow-Electrode Capacitive Deionization". ECS Meeting Abstracts MA2024-01, nr 45 (9.08.2024): 2570. http://dx.doi.org/10.1149/ma2024-01452570mtgabs.
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As access to freshwater diminishes due to climate change and population growth, drought-stricken regions across the globe continue to turn to groundwater and desalination. A largely untapped water resource in many parts of the world is brackish water - defined as water with total dissolved solids (TDS) in the range of 500 ppm to 10,000 ppm. Flow Capacitive Deionization (FCDI) is an electrochemical ion removal technology that is well-suited for the continuous desalination of brackish waters. Traditional Capacitive Deionization (CDI) consists of two fixed capacitive electrodes which are charged and discharged cyclically to capture ions from the solution being treated, and then regenerated to create a waste brine stream. During FCDI operation however, an applied potential drives ions out of a center water channel, typically through a pair of cation and anion exchange membranes (CEM/AEM), and into two flowing capacitive slurry electrodes (Figure 1). Because the electrodes are mobile, they can be moved into an adjacent cell for regeneration, thus enabling continuous operation of the desalination system without cyclical charge/discharge. The cathode and anode slurries typically consist of activated carbon suspended in a salt solution. Because the electrodes are flowing in FCDI, models describing this system must translate the Eulerian derivative to describe transient capacitive charge/discharge to a Lagrangian material derivative following the electrode material flowing through space. A flowing capacitive electrode is a significantly more complex system than a stationary porous and capacitive electrode matrix, incorporating the fluid dynamics of the slurries, ion transport within the slurry’s electrolyte medium, etc. Despite nearly a decade of research into FCDI, few researchers have probed the transient and spatially dependent mechanisms of ion transport and electro-adsoprtion within flow electrodes. While the overall electrodialytic contributions to ion capture within FCDI systems have been studied (1,2), the mechanism of competition between the electrodialysis and capacitive ion capture within the flow electrodes remains somewhat elusive. Additional analysis of the ion transport phenomena within these flow electrodes could bring forth insights into optimal design of FCDI devices and/or electrode formulations. In this study, an existing 2-dimensional mathematical model (3,4) for electrochemical flow capacitors is adapted to FCDI and solved via finite element analysis in COMSOL Multiphysics. Transport equations describing the advection of overpotential along with the flowing electrode are coupled with the Nernst-Planck equations which govern ion transport within the CEM/AEM, center water channel, and slurry electrolyte medium. This study investigates the effect of slurry flow velocity and sodium chloride concentration in the influent water on electrical potential profiles within an FCDI cell, and illustrates the active regions of capacitive electro-adsorption through the depth of the flow channel. Models of electrodialysis and FCDI are compared to understand the fundamental differences in driving forces for ion removal between the two technologies. The model shows agreement with experimental data through prediction of salt adsorption rate trends (mmol NaCl m-2 s-1) vs. influent sodium chloride concentrations. Through this analysis, it is shown that this model may serve as a valuable groundwork for expansion of FCDI modeling capabilities to include three dimensional cell geometries and subsequent optimization of operational parameters and cell dimensions. P. Nativ, Y. Badash, and Y. Gendel, Electrochem. Commun., 76, 24–28 (2017). J. Ma, C. He, C. Zhang, and T. D. Waite, Water Res., 144, 296–303 (2018). N. C. Hoyt, J. S. Wainright, and R. F. Savinell, J. Electrochem. Soc., 152, A652–A657 (2015). N. C. Hoyt, R. F. Savinell, and J. S. Wainright, Chem. Eng. Sci., 144, 288–297(2016). Figure 1
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Zhang, Ying Jie, Jia Guo i Ting Li. "Research Progress on Binder of Activated Carbon Electrode". Advanced Materials Research 549 (lipiec 2012): 780–84. http://dx.doi.org/10.4028/www.scientific.net/amr.549.780.
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The activated carbon electrode has been widely used as an electrode material in capacitive deionization (CDI). The binder of activated carbon electrode has important influence on the electrochemical properties and structures of the electrodes. The effect of binder on the conductivity and capacitance of the electrodes is discussed in this article. And the structures characteristics of electrodes by adding different kinds of binder are summarized. The electrodes have higher capacitance and specific surface using polyvinylalochol (PVA) and sulfosuccinic-acid (SSA) as hydrophilic binder, comparing with hydrophobic binders include phenolicresin, polytetrafluoroethylene (PTFE) and polyvinylidenefluoride (PVDF). Therefore, activated carbon electrodes consisted by PVA and SSA are expected to become the future hot spot. The study of this paper has special significance to the choice and application of the binder in capacitive deionization.
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Lessard-Tremblay, Mathieu, Joshua Weeks, Laura Morelli, Glenn Cowan, Ghyslain Gagnon i Ricardo J. Zednik. "Contactless Capacitive Electrocardiography Using Hybrid Flexible Printed Electrodes". Sensors 20, nr 18 (10.09.2020): 5156. http://dx.doi.org/10.3390/s20185156.
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Traditional capacitive electrocardiogram (cECG) electrodes suffer from limited patient comfort, difficulty of disinfection and low signal-to-noise ratio in addition to the challenge of integrating them in wearables. A novel hybrid flexible cECG electrode was developed that offers high versatility in the integration method, is well suited for large-scale manufacturing, is easy to disinfect in clinical settings and exhibits better performance over a comparable rigid contactless electrode. The novel flexible electrode meets the frequency requirement for clinically important QRS complex detection (0.67–5 Hz) and its performance is improved over rigid contactless electrode across all measured metrics as it maintains lower cut-off frequency, higher source capacitance and higher pass-band gain when characterized over a wide spectrum of patient morphologies. The results presented in this article suggest that the novel flexible electrode could be used in a medical device for cECG acquisition and medical diagnosis. The novel design proves also to be less sensitive to motion than a reference rigid electrode. We therefore anticipate it can represent an important step towards improving the repeatability of cECG methods while requiring less post-processing. This would help making cECG a viable method for remote cardiac health monitoring.
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Al Hajji Safi, Maria, D. Noel Buckley, Andrea Bourke i Robert P. Lynch. "(Invited) Relationship of Pseudo-Capacitive Current in Sulphuric Acid and Vanadium Flow Battery Reaction Kinetics at Carbon Electrodes". ECS Meeting Abstracts MA2023-02, nr 59 (22.12.2023): 2877. http://dx.doi.org/10.1149/ma2023-02592877mtgabs.
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Flow battery technologies are promising solutions to the need for electricity storage driven by the increasing demand for energy supply at the same time as the electricity grid becomes more and more dependent on renewable sources such as solar, wind and ocean energy. Vanadium flow batteries (VFBs) are perhaps the most promising of these technologies and a growing number of commercial systems are in operation worldwide. The energy efficiency of vanadium flow batteries (VFBs) largely depends upon the performance of the electrodes. Poor electrode kinetics cause large overpotentials, which reduce the voltage efficiency. They can also lead to side reactions, such as hydrogen evolution at the negative electrode and oxidation of the positive electrode, which reduce the coulombic efficiency and the overall performance and durability. There is considerable variation in the data regarding the kinetics of vanadium redox reactions at carbon electrodes. We have previously reported that cathodic treatment enhances the kinetics of the positive (VIV-VV) electrode in VFBs but inhibits the kinetics of the negative (VII-VIII) electrode, while anodic treatment inhibits the kinetics of the positive electrode but enhances the kinetics of the negative electrode1-3. We also showed that the activity of carbon-based material is strongly dependent on the surface history, in particular the most positive and the most negative potential used to treat an electrode4. In this presentation we will further investigate the effect of electrochemical treatment of the carbon surface and show the relationship between the observed pseudo-capacitive behavior and the kinetics of the different vanadium redox couples. References Bourke, M. A. Miller, R. P. Lynch, X. Gao, J. Landon, J. S. Wainright, R. F. Savinell and D. N. Buckley, J. Electrochem. Soc. 163, A5097 (2016). A. Bourke, M. A. Miller, R. P. Lynch, J. S. Wainright, R. F. Savinell and D. N. Buckley, J. Electrochem. Soc., 162, A1547 (2015). M. A. Miller, A. Bourke, N. Quill, J. S. Wainright, R. P. Lynch, D. N. Buckley and R. F. Savinell, J. Electrochem. Soc., 163, A2095 (2016). M. Al Hajji Safi, A. Bourke, D. N. Buckley, R. P. Lynch, ECS Trans., 109, 67-84 (2022).
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Vallance, R. Ryan, Eric R. Marsh i Philip T. Smith. "Effects of Spherical Targets on Capacitive Displacement Measurements". Journal of Manufacturing Science and Engineering 126, nr 4 (1.11.2004): 822–29. http://dx.doi.org/10.1115/1.1813476.
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Capacitive displacement sensors are widely used in precision manufacturing and metrology because they measure displacements with nanometer resolution. Prior literature usually treats capacitive sensors consisting of electrodes arranged as parallel plates. In this work, the target electrode is spherical, which is common in machine tool metrology, spindle metrology, and the measurement of sphericity. The capacitance due to a gap between flat and spherical electrodes is less than that of two flat electrodes, which causes four effects. As the diameter of the target electrode is reduced, the sensitivity increases, the sensing range decreases, the sensing range shifts toward the target, and the sensor becomes nonlinear. This paper demonstrates and quantifies these effects for a representative capacitive sensor, using finite element analysis and experimental testing. For larger spheres, the effects are correctible with apparent sensitivities, but measurements with the smallest spheres become increasingly nonlinear and inaccurate.
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Zheng, Peiliang, Yan Deng, Shuxiang Wang i Dechang Wu. "Investigation on capacitive force measuring device with linear output". Journal of Physics: Conference Series 2378, nr 1 (1.12.2022): 012004. http://dx.doi.org/10.1088/1742-6596/2378/1/012004.
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Abstract Capacitive force measuring device is the most precise of all electrical force force measuring devices with its extremely high sensitivity and resolution. The shape of the capacitive electrode had an important influence on the output of the capacitive force measuring device, and a capacitive force measuring device with linear output could be obtained by regulating the shape of the electrode. The functional conditions that the shape of the capacitor electrode needed to meet when the force measuring device had been linearly output are obtained through theoretical analysis. The output characteristics of two electrode shapes satisfying linear output had been studied through the method of combining theoretical analysis and experiment. Results shown that when the electrode shape satisfied the function condition, the experimental data output of the force measuring device had a good linear relationship, and the linearity could reach more than 0.99. The value of the constant term in the electrode shape function had almost no influence on the output linearity of the force measuring device, but had a direct influence on the slope and intercept of the linear output. For the electrodes with a certain shape, the applied voltage only affected the output range of the force measuring device and did not affect its output linearity. The wide range and high-accuracy measurement of the force measuring device could be realized by using the capacitive force measuring device with linear output with setting different fixed-value loading voltages.
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Deguchi, M. "Expansion of detectable area by floating electrodes in capacitive three-dimensional proximity sensor". International Journal on Smart Sensing and Intelligent Systems 14, nr 1 (1.01.2021): 1–11. http://dx.doi.org/10.21307/ijssis-2021-018.
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Abstract In the capacitive proximity sensing method, arranging multiple sensing electrodes makes it possible to obtain the three-dimensional position of a nearby object. The author has developed a capacitive proximity sensing method using LC resonance in three reactance elements. In this method, the detectable area can be greatly extended by the floating electrodes, which are capacitively connected to the sensing electrode. By connecting multiple floating electrodes in series, the detectable range can be extended up to the length of the array of floating electrodes. When these electrodes are arranged on a frame, the region surrounded by the frame becomes the detectable area. By applying this frame on any surface, it is possible to make the surface within the opening of the frame a non-contact operating panel, which can be applied as a gesture input device.
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Chen, Chi-Chun, Shu-Yu Lin i Wen-Ying Chang. "Novel Stable Capacitive Electrocardiogram Measurement System". Sensors 21, nr 11 (25.05.2021): 3668. http://dx.doi.org/10.3390/s21113668.
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This study presents a noncontact electrocardiogram (ECG) measurement system to replace conventional ECG electrode pads during ECG measurement. The proposed noncontact electrode design comprises a surface guard ring, the optimal input resistance, a ground guard ring, and an optimal voltage divider feedback. The surface and ground guard rings are used to reduce environmental noise. The optimal input resistor mitigates distortion caused by the input bias current, and the optimal voltage divider feedback increases the gain. Simulated gain analysis was subsequently performed to determine the most suitable parameters for the design, and the system was combined with a capacitive driven right leg circuit to reduce common-mode interference. The present study simulated actual environments in which interference is present in capacitive ECG signal measurement. Both in the case of environmental interference and motion artifact interference, relative to capacitive ECG electrodes, the proposed electrodes measured ECG signals with greater stability. In terms of R–R intervals, the measured ECG signals exhibited a 98.6% similarity to ECGs measured using contact ECG systems. The proposed noncontact ECG measurement system based on capacitive sensing is applicable for use in everyday life.
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Ullah, Hadaate, Md A. Wahab, Geoffrey Will, Mohammad R. Karim, Taisong Pan, Min Gao, Dakun Lai, Yuan Lin i Mahdi H. Miraz. "Recent Advances in Stretchable and Wearable Capacitive Electrophysiological Sensors for Long-Term Health Monitoring". Biosensors 12, nr 8 (11.08.2022): 630. http://dx.doi.org/10.3390/bios12080630.
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Over the past several years, wearable electrophysiological sensors with stretchability have received significant research attention because of their capability to continuously monitor electrophysiological signals from the human body with minimal body motion artifacts, long-term tracking, and comfort for real-time health monitoring. Among the four different sensors, i.e., piezoresistive, piezoelectric, iontronic, and capacitive, capacitive sensors are the most advantageous owing to their reusability, high durability, device sterilization ability, and minimum leakage currents between the electrode and the body to reduce the health risk arising from any short circuit. This review focuses on the development of wearable, flexible capacitive sensors for monitoring electrophysiological conditions, including the electrode materials and configuration, the sensing mechanisms, and the fabrication strategies. In addition, several design strategies of flexible/stretchable electrodes, body-to-electrode signal transduction, and measurements have been critically evaluated. We have also highlighted the gaps and opportunities needed for enhancing the suitability and practical applicability of wearable capacitive sensors. Finally, the potential applications, research challenges, and future research directions on stretchable and wearable capacitive sensors are outlined in this review.
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Bednar, Tadeas, Branko Babusiak, Michal Labuda, Milan Smetana i Stefan Borik. "Common-Mode Voltage Reduction in Capacitive Sensing of Biosignal Using Capacitive Grounding and DRL Electrode". Sensors 21, nr 7 (6.04.2021): 2568. http://dx.doi.org/10.3390/s21072568.
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A capacitive measurement of the biosignals is a very comfortable and unobtrusive way suitable for long-term and wearable monitoring of health conditions. This type of sensing is very susceptible to noise from the surroundings. One of the main noise sources is power-line noise, which acts as a common-mode voltage at the input terminals of the acquisition unit. The origin and methods of noise reduction are described on electric models. Two methods of noise removal are modeled and experimentally verified in the paper. The first method uses a passive capacitive grounding electrode, and the second uses an active capacitive Driven Right Leg (DRL) electrode. The effect of grounding electrode size on noise suppression is experimentally investigated. The increasing electrode area reduces power-line noise: the power of power-line frequency within the measured signal is 70.96 dB, 59.13 dB, and 43.44 dB for a grounding electrode area of 1650 cm2, 3300 cm2, and 4950 cm2, respectively. The capacitive DRL electrode shows better efficiency in common-mode noise rejection than the grounding electrode. When using an electrode area of 1650 cm2, the DRL achieved 46.3 dB better attenuation than the grounding electrode at power-line frequency. In contrast to the grounding electrode, the DRL electrode reduces a capacitive measurement system’s financial costs due to the smaller electrode area made of the costly conductive textile.
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Uchida, N., M. Moriyama, A. Kawaguchi, M. Yokokawa, S. Ikeda, H. Kitagaki i H. Kato. "An RF hyperthermia electrode which generates no edge effect". Journal of Clinical Oncology 27, nr 15_suppl (20.05.2009): e22229-e22229. http://dx.doi.org/10.1200/jco.2009.27.15_suppl.e22229.
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e22229 Background: For local hyperthermia cancer therapy, radio frequency (RF) capacitive heating with a pair of electrodes is one of the most effective methods. RF hyperthermia with a conventional 2-dimensional square plate electrode produces an ‘edge effect‘ - the focusing of the RF current resulting in focal overheating. We designed and propose a novel hemispherical-shaped RF capacitive heating electrode that generates no edge effect. Methods: A CAD simulation (COMSOL Multiphysics 3.4) was done, and current and specific absorbance ratio (SAR) distributions of both the hemispherical and the conventional square plate shape electrodes were obtained by a 3-D finite element method. Results: The hemispherical electrode generated no focusing of current distribution, nor overheating with SAR elevation, while the square plate electrode produced an edge effect with local SAR elevation. Conclusions: The hemispherical electrode showed no edge effect from focal overheating. Our new electrode may be useful for local heating in the oral or vaginal cavity in clinical use. Phantom studies with a prototype electrode should be carried out for further confirmation. No significant financial relationships to disclose.
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Kang, Younghwan, Sangdong Choi, Chiwan Koo i Yeunho Joung. "Development and Optimization of Silicon−Dioxide−Coated Capacitive Electrode for Ambulatory ECG Measurement System". Sensors 22, nr 21 (1.11.2022): 8388. http://dx.doi.org/10.3390/s22218388.
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This paper presents a silicon−dioxide−coated capacitive electrode system for an ambulatory electrocardiogram (ECG). The electrode was coated with a nano−leveled (287 nm) silicon dioxide layer which has a very high resistance of over 200 MΩ. Due to this high resistance, the electrode can be defined as only a capacitor without a resistive characteristic. This distinct capacitive characteristic of the electrode brings a simplified circuit analysis to achieve the development of a high−quality ambulatory ECG system. The 240 um thickness electrode was composed of a stainless−steel sheet layer for sensing, a polyimide electrical insulation layer, and a copper sheet connected with the ground to block any electrical noises generated from the back side of the structure. Six different diameter electrodes were prepared to optimize ECG signals in ambulatory environment, such as the amplitude of the QRS complex, amplitude of electromagnetic interference (EMI), and baseline wandering of the ECG signals. By combining the experimental results, optimal ambulatory ECG signals were obtained with electrodes that have a diameter from 1 to 3 cm. Moreover, we achieved high−quality ECG signals in a sweating simulation environment with 2 cm electrodes.
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Jo, Kyusik, Youngbin Baek, Changha Lee i Jeyong Yoon. "Effect of Hydrophilicity of Activated Carbon Electrodes on Desalination Performance in Membrane Capacitive Deionization". Applied Sciences 9, nr 23 (23.11.2019): 5055. http://dx.doi.org/10.3390/app9235055.
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Membrane capacitive deionization (MCDI) is a modification of capacitive deionization (CDI) using ion-exchange membranes (IEM) in front of the electrodes. Electrode properties, especially the specific surface area, are known to be strongly related with desalination performance in CDI, but the effects of other properties in MCDI are not fully understood. The objective of this study was to investigate the effect of hydrophilicity in activated carbon electrodes on desalination performance in MCDI. Two types of activated carbon (P60 and YS-2) whose specific surface areas were similar were used as electrode materials, but they had different hydrophilicity (i.e., P60 was originally hydrophobic and YS-2 was relatively hydrophilic due to its nitrogen-containing surface chemistry). These hydrophilic electrodes (either the electrode itself or modified with polydopamine (PDA)) led to an increase in the salt adsorption capacity (SAC) in MCDI because they facilitated the access of both ions and water molecules into the electrode pores. In particular, the SAC of the P60 electrode displayed a large increase to almost reach that of the YS-2 electrode due to the improved hydrophilicity with PDA modification and the insignificant effects of PDA modification on an already hydrophilic YS-2 electrode. Additionally, PDA-modified IEM in MCDI reduced the SAC as a result of the additional insulating PDA layer with little changes in hydrophilicity.
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Cao, Cuihui, Xiaofeng Wu, Yuming Zheng, Donghai Zhang, Jianhua Chen i Yunfa Chen. "Ordered Mesoporous Carbon with Chitosan for Disinfection of Water via Capacitive Deionization". Nanomaterials 10, nr 3 (9.03.2020): 489. http://dx.doi.org/10.3390/nano10030489.
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Capacitive deionization (CDI) with water disinfection materials is a potential method to produce fresh water from aqueous solutions. Therefore, an ordered mesoporous carbon with chitosan (OMC-CS) was coated on the active carbon (AC) electrode as a capacitive deionization disinfection (CDI) electrode. Comparing with OMC-CS-4,6,8 as CDI electrodes, it was found that OMC-CS-6 as a CDI electrode had an excellent disinfection efficiency, killing about 99.99% Escherichia coli (E. coli) in the CDI process at an applied 1.2 V. The OMC-CS material was did not pollute the water and will not contaminate to the environment in comparison with other chemical antibacterial agents. This CDI electrode could play a huge role in biocontaminated water in the future.
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Popov, Maxim V., Alexander G. Bannov i Stepan I. Yusin. "Carbon nanomaterials for supercapacitors: two electrode scheme". MATEC Web of Conferences 340 (2021): 01035. http://dx.doi.org/10.1051/matecconf/202134001035.
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In this paper, the electrochemical and texture characteristics of electrode materials made of a number of promising carbon materials for supercapacitors were considered. Carbon nanofibers, thermally expanded graphite, and activated carbon derived from rice hulls were used as electrodes for supercapacitors. The paper presents a technique of synthesis of these electrode materials. A comparison of the capacitive characteristics of the electrodes using two-electrode scheme was carried out.
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Habib, Ahsan. "Chicken Feathers-Derived Carbon Electrodes for Capacitive Deionization". ECS Meeting Abstracts MA2023-02, nr 9 (22.12.2023): 1035. http://dx.doi.org/10.1149/ma2023-0291035mtgabs.
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Capacitive deionization (CDI) is an emerging technology which is being developed as a promising desalination alternative for charged species from salt water, being electrode materials as key drivers for highly efficient process. In this study, we report sustainable, scalable and stable carbon electrodes for CDI. Electrodes were synthesized from poultry chicken feathers waste using pyrolysis followed by chemical activation with potassium hydroxide at a 1:4 ratio to produce highly porous carbon. Poultry chicken feathers-activated carbon (CF-AC) were prepared and fabricated into electrodes using poly(vinyl alcohol) (PVA) binder and later crosslinked with glutaraldehyde (GA) to produce a PVA-GA polymer due to its hydrophilicity by acetylation reaction to improve the resistance of carbon material. Prepared materials were characterized using scanning electron microscopy, Fourier transform infrared, X-ray diffraction, Brunauer-Emmett-Teller and cyclic voltammetry. Fabricated CDI electrodes were used to investigate their performance for desalination, and exhibited different electrosorption capacity at different applied potentials. Modified electrode possessed good stability in shear conditions and CDI process was stable and reproducible around 16 electrosorption cycles. Salt removal capacity of PVA-GA-bonded CF-AC (PVA-GA-CF-AC) electrodes was found to be 3.89 mg g-1. The obtained outcomes offer important considerations of ions electrosorption and help advancing CDI system for water treatment and desalination.
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Evtushenko, Gennadiy, Inna A. Lezhnina, Artem I. Morenetz, Boris N. Pavlenko, Arman A. Boyakhchyan, Stanislav N. Torgaev i Irina Nam. "Development of medical capacitive coupling electrodes using the skin-electrode contact control". Sensor Review 40, nr 3 (11.04.2020): 347–54. http://dx.doi.org/10.1108/sr-11-2019-0289.
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Purpose The purpose of this paper is the development and study of capacitive coupling electrodes with the ability to monitor the quality of the skin–electrode contact in the process of electrocardiogram (ECG) diagnostics. The study’s scope embraces experimental identification of distortions contributed into the recorded ECG signal at various degrees of disturbance of the skin–electrode contact. Design/methodology/approach A capacitive coupling electrode is designed and manufactured. A large number of experiments was carried out to record ECG signals with different quality of the skin–electrode contact. Using spectral analysis, the characteristic distortions of the ECG signals in the event of contact disturbance are revealed. Findings It was found that the violation of the skin–electrode contact leads to significant deterioration in the recorded signal. In this case, the most severe distortions appear with various violations of the skin–electrode contact of two sensors in one lead. It has been experimentally shown that the developed sensor allows monitoring the quality of the contact, and therefore, improvement of the quality of signal registration, enabled by the use of bespoke processing algorithms. Practical implications These sensors will be used in personalized medicine devices and tele-ECG devices. Originality/value In this work, authors studied the effect of the skin–electrode contact of a capacitive electrode with the body on the quality of the recorded ECG signal. Based on the studies, the necessity of monitoring contact was shown to improve the quality of diagnostics provided by personalized medicine devices; the capacitive sensor with contact feedback was developed.
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Jiang, Shaojie, Hongwu Wang, Guanquan Xiong, Xinlei Wang i Siying Tan. "Removal of nitrate using activated carbon-based electrodes for capacitive deionization". Water Supply 18, nr 6 (1.02.2018): 2028–34. http://dx.doi.org/10.2166/ws.2018.025.
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Abstract The removal performance of nitrate using capacitive deionization (CDI) of activated carbon (AC)-based electrodes were studied. The AC electrode was prepared and the effect of cell voltage, flow rate and initial solution concentration on ion removal were investigated. Furthermore, the AC was modified with phosphoric acid (ACP) and the surface structure of AC and ACP were analyzed. The results showed that the specific surface area of AC increased by 10.71% after the modification. The mesopore ratio and micropore ratio increased by 14.69% and 24.06%, respectively. The optimal conditions of AC electrode was a voltage of 1.4 V and flow rate of 20 mL/min while the ACP electrode was a voltage of 1.4 V and flow rate of 10 mL/min. The electrosorption capacity of ACP electrode was improved and the unit of electrosorption load was high to 19.28 mg/L. For the AC or ACP electrode, the nitrate removal efficiency decreases with the increase in the initial feed solutions, but the unit electrosorption load gradually increased with the improvement of initial feed solutions' concentration and the ACP electrode was superior to the AC electrode. Therefore, the ACP electrode would be suitable for the application of CDI on the nitrate removal.
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Liu, Hong, Qi Wang, Wenjie Sheng, Xubo Wang, Kaidi Zhang, Lin Du i Jia Zhou. "Humidity Sensors with Shielding Electrode Under Interdigitated Electrode". Sensors 19, nr 3 (6.02.2019): 659. http://dx.doi.org/10.3390/s19030659.
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Recently, humidity sensors have been investigated extensively due to their broad applications in chip fabrication, health care, agriculture, amongst others. We propose a capacitive humidity sensor with a shielding electrode under the interdigitated electrode (SIDE) based on polyimide (PI). Thanks to the shielding electrode, this humidity sensor combines the high sensitivity of parallel plate capacitive sensors and the fast response of interdigitated electrode capacitive sensors. We use COMSOL Multiphysics to design and optimize the SIDE structure. The experimental data show very good agreement with the simulation. The sensitivity of the SIDE sensor is 0.0063% ± 0.0002% RH. Its response/recovery time is 20 s/22 s. The maximum capacitance drift under different relative humidity is 1.28% RH.
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Linnartz, Christian J., Alexandra Rommerskirchen, Joanna Walker, Janis Plankermann-Hajduk, Niklas Köller i Matthias Wessling. "Membrane-electrode assemblies for flow-electrode capacitive deionization". Journal of Membrane Science 605 (czerwiec 2020): 118095. http://dx.doi.org/10.1016/j.memsci.2020.118095.
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MacDonald, Michael, i Igor Zhitomirsky. "Capacitive Properties of Ferrimagnetic NiFe2O4-Conductive Polypyrrole Nanocomposites". Journal of Composites Science 8, nr 2 (30.01.2024): 51. http://dx.doi.org/10.3390/jcs8020051.
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This investigation addresses increasing interest in advanced composite materials, combining capacitive properties and spontaneous magnetization for energy storage applications in supercapacitors. The capacitive properties of ferrimagnetic NiFe2O4 (NFO) spinel nanoparticles with magnetization of 30 emu g−1 were enhanced using high-energy ball-milling and the use of advanced dispersant, which facilitated charge transfer. NFO electrodes with an active mass of 40 mg cm−2 showed a capacitance of 1.46 F cm−2 in 0.5 M Na2SO4 electrolyte in a negative potential range. The charging mechanism in the negative potential range in Na2SO4 electrolyte was proposed. NFO was combined with conductive polypyrrole polymer for the fabrication of composites. The analysis of the capacitive behavior of the composites using cyclic voltammetry, chronopotentiometry and impedance spectroscopy at different electrode potentials revealed synergy of contributions of NFO and PPy. The highest capacitance of 6.64 F cm−2 was obtained from cyclic voltammetry data. The capacitance, impedance, and magnetic properties can be varied by variation of electrode composition. Composite electrodes are promising for application in anodes of asymmetric magnetic supercapacitors for energy storage and magnetically enhanced capacitive water purification devices.
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Polz, Mathias, Thomas Rath, Gregor Trimmel, Sara Stoppacher, Marta Nowakowska, Karin Kornmüller, Niroj Shestha, Christian Baumgartner i Theresa Rienmüller. "Holistic Equivalent Circuit Model for Capacitive Extracellular Stimulation". Current Directions in Biomedical Engineering 8, nr 2 (1.08.2022): 777–80. http://dx.doi.org/10.1515/cdbme-2022-1198.
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Abstract Capacitive extracellular stimulation is a common method in implanted stimulation electrodes. The basis for investigating the transmission of stimuli from an electrode to adhered cells are in vitro experiments using calcium imaging or patch clamp measurements. Computational spatial models are used to simulate the mechanism of signal transmission at the cell-electrode interface but require high computing power. In this work, the Stern model to characterize the electrochemical double-layer (EDL) formation and a modified two-domain model are combined into a holistic equivalent circuit modelling capacitive cell stimulation. The described parameters can be directly associated with physicochemical effects. A simulation of the involved control and measurement systems allows the validation of the model with in vitro patch clamp recordings. The relationship of the cell’s distance to the electrode and efficacy of signal transmission could be observed. With this concept we aim to convert different complex approaches into a simple model and thus give an overview of the mechanisms of stimulation. We want to facilitate the interpretation of measured signals especially in voltage clamp measurements.
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Chang-Bin, Tang, Niu Hao, Lu Yu-Xuan, Wang Fei, Zhang Yu-Jie i Xue Juan-Qin. "Electrodeposited MnO2-based Capacitive Composite Electrodes for Pb2+ Adsorption". Revista de Chimie 71, nr 7 (4.08.2020): 284–98. http://dx.doi.org/10.37358/rc.20.7.8247.
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In order to effectively realize the removal of low concentrations of lead ions in wastewater via capacitive deionization technology, MnO2 composite electrodes were prepared by a galvanostatic co-deposition approach, where polyaniline (PANI) and graphene were added to an MnO2 deposition solution and nickel foam was chosen as the substrate of the electrode. The microstructure, capacitance characteristics and adsorption behavior of Pb2+ ions of the electrodes were analyzed by scanning electron microscopy, X-ray diffraction, X ray photoelectron spectroscopy, laser Raman spectroscopy, cyclic voltammetry and capacitance deionization processes. The experimental results showed that the MnO2-PANI-graphene composite electrode has a high specific capacitance (132.8 F/g) and a 61.8% removal rate for simulated wastewater containing 20 mg/L Pb2 + ions under the conditions of 30�C and 1 mA/cm2, with the addition of 1 g/L PANI and 3 g/L graphene, respectively. Electroadsorption process was in accordance with the Lagergren quasi-second-order kinetic equation. The co-deposition of PANI and graphene oxide could play obvious role in enhancing the adsorption capacity and stability of the electrodes.
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Hussain, Humair, Asim Jilani, Numan Salah, Ahmed Alshahrie, Adnan Memić, Mohammad Omaish Ansari i Joydeep Dutta. "Freestanding Activated Carbon Nanocomposite Electrodes for Capacitive Deionization of Water". Polymers 14, nr 14 (16.07.2022): 2891. http://dx.doi.org/10.3390/polym14142891.
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Freshwater reserves are being polluted every day due to the industrial revolution. Man-made activities have adverse effects upon the ecosystem. It is thus the hour of need to explore newer technologies to save and purify water for the growing human population. Capacitive deionization (CDI) is being considered as an emerging technique for removal of excess ions to produce potable water including desalination. Herein, cost-effective activated carbon incorporated with carbon nanotubes (CNT) was used as a freestanding electrode. Further, the desalination efficiency of the designed electrodes was tuned by varying binder concentration, i.e., polyvinylidene difluoride (PVDF) in the activated carbon powder and CNT mixture. PVDF concentration of 5, 7.5, 10, and 12.5 wt% was selected to optimize the freestanding electrode formation and further applied for desalination of water. PVDF content affected the surface morphology, specific surface area, and functional groups of the freestanding electrodes. Moreover, the electrical conductivity and specific surface area changed with PVDF concentration, which ultimately affected the desalination capacity using the freestanding electrodes. This study paves the way to produce cost effective carbon-based freestanding electrodes for capacitive deionization and other applications including battery electrodes.
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Dou, Chen, Shengyong Zhai, Yiyang Liu, Peng Chen, Di Yin, Guangtuan Huang i Lehua Zhang. "Chemical modification of carbon particles to enhance the electrosorption of capacitive deionization process". Journal of Water Reuse and Desalination 10, nr 1 (25.02.2020): 57–69. http://dx.doi.org/10.2166/wrd.2020.052.
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Abstract Activated carbon particle electrodes modified by oxygen or nitrogen groups could be promising electrode candidates for capacitive deionization (CDI) processes. In this work, activated carbon particle electrodes were modified by phosphoric acid, nitric acid, urea, melamine, and zinc chloride to enhance desalination of an aqueous electrolytic solution. The modified activated carbon particles were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller measurements and electrochemical scanning. The electrodes with oxygen or nitrogen groups on the surface exhibited a much higher desalination capacity and charge efficiency than those without any surface modification. Particularly, the activated carbon particle electrode modified by phosphoric acid exhibited a desalination capacity of 15.52 mg/g at 1.4 V in 500 mg/L NaCl solution, which was approximately eight times that of the unmodified electrode (2.46 mg/g). The enhancement was attributed to a higher specific capacitance, a lower electrochemical impedance and an increase in oxygen or nitrogen-containing groups on the surface.
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Golabzaei, Sabereh, Ramin Khajavi, Heydar Ali Shayanfar, Mohammad Esmail Yazdanshenas i Nemat Talebi. "Fabrication and characterization of a flexible capacitive sensor on PET fabric". International Journal of Clothing Science and Technology 30, nr 5 (3.09.2018): 687–97. http://dx.doi.org/10.1108/ijcst-08-2017-0125.
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Purpose There is a developing interest in flexible sensors, especially in the new and intelligent generation of textiles. The purpose of this paper is to fabricate a flexible capacitive sensor on a PET fabric and to investigate some affecting factor on its performance. Design/methodology/approach PET fabric, coated with graphite or with graphite/PEDOT:PSS, was applied as electrodes. Two types of electrospun nanoweb layers from polyamide and polyvinyl alcohol polymers were used as dielectrics. Some factors including electrode area, fabric conductivity, fabric roughness, dielectric thickness, dielectric insulation type and vertical pressure were considered as independent variables. The capacity of the sensor and its detection threshold considered as the outcome (response) variables. Control samples were fabricated by using aluminum plates and cellulosic layer as electrodes and dielectric, respectively. Findings Results showed that post-coating with PEDOT:PSS would improve the conductivity of electrodes up to 300 Ω in comparison with just graphite-coated samples. It was also found that either by improving the conductivity or increasing the area of electrode plates the sensitivity of sample would be increased in pressure stimulating tests. Originality/value The fabric sensor showed remarkable response toward pressure with a lower detection threshold of 30mN/cm2 (obtained capacity ~ 4×104 pF) in comparison with aluminum electrode sensors.
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Li, Wang, Lei Lei, Zhou Yun i Fu Jiangtao. "Fabrication of titanium carburizing electrodes for capacitive deionization". Water Science and Technology 76, nr 4 (20.04.2017): 754–60. http://dx.doi.org/10.2166/wst.2017.210.
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Titanium carburizing electrodes were used as the electrodes in a capacitive deionization (CDI) process for desalination in this study. Two methods of high vacuum magnetron sputtering and chemical deposition were used for the preparation of nano-titanium carburizing electrodes (named Ti-C* and Ti-C**). By comparing the adsorption capacities of different kinds of electrode material, combined with physical and chemical characteristics and electrochemical analysis, the method of high vacuum magnetron sputtering to prepare Ti-C* electrodes have been proved successful for the CDI process. The results show that under the same conditions, the adsorption capacity of Ti-C* and Ti-C**were 9.6 mg/g and 7.12 mg/g, respectively. The Ti-C* electrodes showed a higher ion electrosorption capacity than Ti-C** and the electrodes can be easily regenerated, indicating excellent recyclability. This study provided a novel method to fabricate titanium carburizing electrodes in CDI process and might lead to the improvement of the CDI desalination performance in an industrial practical application.
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Thangavel, Sathies, i Senthil Ponnusamy. "Application of 3D printed polymer composite as capacitive sensor". Sensor Review 40, nr 1 (29.11.2019): 54–61. http://dx.doi.org/10.1108/sr-08-2019-0198.
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Purpose The purpose of this study is to demonstrate the usage of three-dimensionally (3D) printed polylactic acid (PLA)-carbon black (CB) conductive polymer composite in the measurement of the void fraction and liquid level. Design/methodology/approach PLA-CB conductive polymer composite is 3D printed through fused deposition modelling (FDM) technique and used as a capacitive sensor for void fraction measurement and liquid level sensing. The sensitivity of 3D printed ring and concave type capacitive sensors are compared for void fraction measurement. The effect of electrode length, thickness and pipe dimension on the capacitance achievable for the particular void fraction is studied. Concept of fringing capacitance is used for the sensing of liquid level. Findings Compared to the concave design comprising four electrodes, the ring-type capacitive sensor produced better results in void fraction measurement. Increase in pipe diameter and electrode length results in the enhancement of capacitance arising from specific void fraction. For a 100 mm diameter pipe, the capacitance of the 150 mm-long concave electrode (0.4 mm thick) increased from 9.98 to 67.77 pF as the void fraction decreased from 100% to 0%. Development of the fringing capacitance in 3D printed PLA-CB composite helps in the measurement of liquid level. Both parallel finger topology and interdigital electrode configuration are able to sense the liquid level. Originality/value Ability of the 3D printed conductive PLA-CB composite to act as a capacitive sensor is experimentally analysed. Performance of different electrode configuration is tested for both void fraction measurement and liquid level sensing. Results of experimentation prove that FDM printed PLA-CB composite is suitable for the void fraction and liquid level measurement.
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Mazumder, Prantik, Todd StClair i Roy Bourcier. "(Invited) Capacitive Deionization (CDI) – an Industrial Research Perspective". ECS Meeting Abstracts MA2023-01, nr 27 (28.08.2023): 1762. http://dx.doi.org/10.1149/ma2023-01271762mtgabs.
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As the demand for freshwater keeps increasing due to industrialization and population growth, the world is progressively interested in desalination for sourcing potable water. While membrane-based reverse osmosis (RO) and thermal-based evaporation/distillation are proven technologies for desalination, they are also expensive. Capacitive deionization (CDI) - introduced in the 1970s - where the positive and negative ions are separated by the application of an electric field across pairs of high surface area electrodes, has been considered as a potentially cheaper technology. In the mid-2000s, Corning carried out a research project on developing CDI. The workstreams involved developing novel materials for electrodes, new device architecture, predictive theoretical models at electrode and device scales, and eventually a plant-level cost analysis that connected the electrode and device-level parameters to the final cost of water desalination, in $/gallon, which is the ultimate arbiter for techno-economic feasibility. We made significant progress in: (a) developing thin all-carbon electrodes which were electrochemically inert, highly conductive, and possessed high specific capacitance (F/cc) (b) designing a flow-past device architecture based on stacked planar electrodes with a small footprint (c) developing user-friendly simplified theoretical models, and (d) formulating two high-level figures of merit (FOM), namely, volumetric efficiency (VE) and recovery ratio (RR) – both of which need to be maximized to compete against incumbent technologies such as RO, especially in the high-throughput brackish water market sector. Our prototype achieved an equivalent VE of ~40 kg/ft3/day of salt removal. However, the plant-level cost analysis suggested that there is not much room for improving the overall cost structure compared to RO even with such high device level performance for high throughput desalination markets. In this talk we will present our experience with the development of CDI technology. We will cover all aspects of the project - electrode materials development, device architecture, theoretical models, and cost analysis – and will also offer an industrial perspective on CDI technology development, particularly when it comes to competing against well-established and entrenched technologies. We will also highlight how systems-level thinking and analyses are extremely important for such technology assessments and point out that only focusing on lab-scale performance metrics can be misleading.
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Pothanamkandathil, Vineeth, i Christopher A. Gorski. "Charge Redistribution Reactions in Intercalation Electrodes Used for Capacitive Deionization". ECS Meeting Abstracts MA2022-02, nr 27 (9.10.2022): 1050. http://dx.doi.org/10.1149/ma2022-02271050mtgabs.
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Electrodes used for capacitive deionization (CDI) are prone to self-discharge reactions, in which their electrochemical potentials can drift over time under open-circuit conditions. These self-discharge reactions inhibit energy recovery during the cell discharge step when operating CDI cells, which increases the amount of energy required to deionize water. Self-discharge reactions for porous carbon electrodes are well-documented in the literature, where they have been attributed primarily to parasitic faradaic reactions and charge redistribution reactions in pore networks. Little work, however, has examined how and why self-discharge reactions occur for electrodes that intercalate cations into their structures. Here, we report that nickel hexacyanoferrate, a Prussian blue analog, undergoes significant self-discharge under open-circuit conditions in neutral saline solutions, which adversely impacts its use in deionization cells. We examined how the charging history, charging process, and electrolyte composition influenced self-discharge. Preliminary evidence indicates that self-discharge is largely a consequence of charge redistribution within the crystal lattice. Our findings provide insights into the feasibility of using Prussian blue analogs as electrode materials for deionization as well as caution in how salt absorption capacities of electrode materials are quantified.
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Ho, M. Y., Poi Sim Khiew, D. Isa, T. K. Tan, W. S. Chiu i C. H. Chia. "LiFePO4 - Activated Carbon Composite Electrode as Symmetrical Electrochemical Capacitor in Mild Aqueous Electrolyte". Applied Mechanics and Materials 627 (wrzesień 2014): 3–6. http://dx.doi.org/10.4028/www.scientific.net/amm.627.3.
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In this study, a symmetric electrochemical capacitor has been fabricated by adopting the lithiated compound (LiFePO4)-activated carbon (AC) composite as the core electrode materials. The electrochemical performances of the prepared supercapacitor were studied using cyclic voltammetry (CV) in 1.0 M Na2SO3 solution. Experimental results reveal that the maximum specific capacitance of 112.41 F/g is obtained in 40 wt % LiFePO4 loading on AC electrode in comparison to that of pure AC electrode (76.24 F/g) in 1 M Na2SO3. The enhanced capacitive performance of the 40 wt % LiFeO4 –AC composite electrode is believed attributed to the contribution of synergistic effect of electric double layer capacitance (EDLC) on the surface of AC as well as pseudocapacitance via intercalation/extraction of Na+, SO32-and Li+ ions in LiFePO4 lattices. The composite electrodes can sustain a stable capacitive performance at least 1000 cycles with only ~5 % specific capacitance loss after 1000 cycles. Based on the findings above, 40 wt % LiFeO4 –AC composite electrodes which utilise low cost materials and environmental friendly electrolyte is worth being investigated in more details.
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Tasnim, Rumana, Sheroz Khan, Musse Mohamud i Atika Arshad. "A QUALITATIVE ANALYSIS OF BIOMASS FLOW SENSING BEHAVIOR USING CAPACITIVE TECHNIQUE". IIUM Engineering Journal 17, nr 1 (30.04.2016): 29–40. http://dx.doi.org/10.31436/iiumej.v17i1.459.
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Flowsensing technology from today’s application perspective has gained significant research interest over the past few years. Among the existing sensing techniques, electrostatic and capacitive sensing techniques have proven promising although cable capacitance and stray capacitance cause inaccuracy while measuring very small capacitances. The existing measurement circuit model is complicated and has flawed electrode arrangement. By sensing very small capacitive variation, the developed capacitive technique has proven capable of reducing the stray and residual capacitance effect by using an interface sensing circuit based on circular and semicircular shaped electrode and modified capacitive bridge. The proposed interface circuit is simulated via PSPICE for realizing the small capacitive variation with permittivity variation. Hardware implementation is carried out using a flow sensing set up that senses two kinds of biomass flow variation as a change of dielectric permittivity under room conditions. The output voltage has been reproduced as a representative of the flow. Moreover, a comprehensive investigation into experimental data shows an agreeable level of consistency with the simulation results.KEYWORDS: electrodes; sensing; capacitance; electrostatic; piping; measurement
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Himanshu, S. Rao, Dinah Punnoose, P. Sathishkumar, Chandu Gopi, Naresh Bandari, Ikkurthi Durga, T. Krishna i Hee-Je Kim. "Development of Novel and Ultra-High-Performance Supercapacitor Based on a Four Layered Unique Structure". Electronics 7, nr 7 (19.07.2018): 121. http://dx.doi.org/10.3390/electronics7070121.
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This paper presents an electrode with a core/shell geometry and a unique four-layered porous wrinkled surface for pseudocapacitive supercapacitor applications. To design the electrode, Ni foam was used as a substrate, where the harmonious features of four constituents, ZnO (Z), NiS (N), PEDOT:PSS (P), and MnO2 (M) improved the supercapacitor electrochemical performance by mitigating the drawbacks of each other component. Cyclic voltammetry and galvanostatic charge discharge measurements confirmed that the ZNPM hybrid electrode exhibited excellent capacitive properties in 2 M KOH compared to the ZNP, ZN, and solely Z electrodes. The ZNPM electrode showed superior electrochemical capacitive performance and improved electrical conductivity with a high specific capacitance of 2072.52 F g−1 at 5 mA, and a high energy density of 31 Wh kg−1 at a power density of 107 W kg−1. Overall, ZNPM is a promising combination electrode material that can be used in supercapacitors and other electrochemical energy conversion/storage devices.
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Tang, Yue, Ronghui Chang, Limin Zhang i Feng Yan. "An Interference Suppression Method for Non-Contact Bioelectric Acquisition". Electronics 9, nr 2 (8.02.2020): 293. http://dx.doi.org/10.3390/electronics9020293.
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For non-contact bioelectrical acquisition, a new interference suppression method, named ‘noise neutralization method’, is proposed in this paper. Compared with the traditional capacitive driven-right-leg method, the proposed method is characterized with that there is an optimal gain to achieve the minimum interference output whatever for the electrode interface impedance mismatch caused by body motion and is more effective for smaller reference electrode areas. The performance of traditional capacitive driven-right-leg method is analyzed and the difficulty to suppress interference in the case of the interface impedance mismatch is pointed out. Therefore, a noise neutralization method is proposed by applying the reference electrode and a 50 Hz band-pass filter to obtain the interference of the human body and adapting the gains to neutralize the interference inputs of two acquisition electrodes and achieve the minimum interference output. The performance of the proposed method is theoretically analyzed and verified by the experiment results, which shows that the proposed method has similar performance to that of the traditional capacitive driven-right-leg method with electrode interface impedance match, while has better interference suppression ability with electrode interface impedance mismatch caused by body motion. It is suggested that the proposed method can be preferred in the case of limited reference electrode area or interface impedance mismatch.
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Choo, Ko Yeon, Chung Yul Yoo, Moon Hee Han i Dong Kook Kim. "Electrochemical analysis of slurry electrodes for flow-electrode capacitive deionization". Journal of Electroanalytical Chemistry 806 (grudzień 2017): 50–60. http://dx.doi.org/10.1016/j.jelechem.2017.10.040.
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Lee, Jaehan, Seoni Kim, Choonsoo Kim i Jeyong Yoon. "Hybrid capacitive deionization to enhance the desalination performance of capacitive techniques". Energy Environ. Sci. 7, nr 11 (2014): 3683–89. http://dx.doi.org/10.1039/c4ee02378a.
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Yamamoto, Kentaro, Yoshifumi Nishida, Ken Sasaki, Dairoku Muramatsu i Fukuro Koshiji. "Electromagnetic Field Analysis of Signal Transmission Path and Electrode Contact Conditions in Human Body Communication". Applied Sciences 8, nr 9 (3.09.2018): 1539. http://dx.doi.org/10.3390/app8091539.
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Human body communication (HBC) is a wireless communication method that uses the human body as part of the transmission medium. Electrodes are used instead of antennas, and the signal is transmitted by the electric current through the human body and by the capacitive coupling outside the human body. In this study, direction of electric field lines and direction of electric current through the human body were analyzed by the finite-difference time-domain method to clarify the signal path, which is not readily apparent from electric field strength distribution. Signal transmission from a transmitter on the subject’s wrist to an off-body receiver touched by the subject was analyzed for two types of transmitter electrode settings. When both the signal and ground electrodes were put in contact with the human body, the major return path consisted of capacitive coupling between the receiver ground and the human body, and the electric current through the human body that flowed back to the ground electrode of the transmitter. When the ground electrode was floating, the only return path was through the capacitive coupling of the floating ground. These results contribute to the better understanding of signal transmission mechanism of HBC and will be useful for developing HBC applications.
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Liu, Yong, Yue Zhang, Yuchen Zhang, Qing Zhang, Xin Gao, Xinyue Dou, Haiguang Zhu, Xun Yuan i Likun Pan. "MoC nanoparticle-embedded carbon nanofiber aerogels as flow-through electrodes for highly efficient pseudocapacitive deionization". Journal of Materials Chemistry A 8, nr 3 (2020): 1443–50. http://dx.doi.org/10.1039/c9ta11537d.
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Highly efficient pseudo-capacitive deionization systems equipped with flow-through electrodes are developed for the first time based on the utilization of MoC nanoparticle-embedded carbon nanofiber aerogels as electrode materials.
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Li, Zhen, Guoming Chen, Yue Gu, Kefan Wang, Wei Li i Xiaokang Yin. "Further Investigations into the Capacitive Imaging Technique Using a Multi-Electrode Sensor". Applied Sciences 8, nr 11 (19.11.2018): 2296. http://dx.doi.org/10.3390/app8112296.
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As a novel non-destructive testing technique, capacitive imaging (CI) has been used to detect defects within the insulation layer and metal surface of an insulated metallic structure, that is, pipe or vessel. Due to the non-linearity of the probing field, the defects at different depths in the insulation layer are difficult to compare accurately using the conventional CI sensor with a single pair of electrodes. In addition, the conventional CI sensor cannot provide adequate information to discriminate the defects in the insulation layer and metal surface. In order to solve the above-mentioned problems, the multi-electrode sensor is introduced. The multi-electrode sensor uses multiple quasi-static fringing electric fields generated by an array of coplanar electrodes to obtain extra information about the defects in the specimen. In this work, the feasibility of multiple quasi-static electric fields detecting the defects was demonstrated and the Measurement Sensitivity Distributions (MSDs) of the multi-electrode sensor detecting the defects were acquired using the FEM models. The simulation and experimental results show that the Dynamic Change Rates (DCRs) of the measured values obtained at the center of the defects in the insulator layer and metal surface present different variation patterns, which can be used to discriminate these two different kinds of defects. The reasons for the different variation patterns of DCRs were explained by the changing trends of MSDs with increased electrode separation. In addition, it was demonstrated that the different depths of the defects in the insulator layer can be compared accurately by comprehensive analysis of the detection results from all the electrode pairs.
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HUANG, WEI, YIMIN ZHANG, SHENXU BAO i SHAOXIAN SONG. "DESALINATION BY CAPACITIVE DEIONIZATION WITH CARBON-BASED MATERIALS AS ELECTRODE: A REVIEW". Surface Review and Letters 20, nr 06 (grudzień 2013): 1330003. http://dx.doi.org/10.1142/s0218625x13300050.
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Capacitive deionization (CDI) is a recently developed electrosorption technology for deionization using porous electrodes. The electrode materials play an important role in the efficiency. This paper highlights the current research status of carbon-based materials as the electrode and the adsorption models in the CDI. It includes the types and performances of carbon-based materials and the main influencing factors of the desalination characteristics. Also, operating parameters such as charging voltage, flow rate, concentration of feed solution, treating time and temperature are summarized.