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For years, capacitive electrocardiogram (CECG) has been known to be susceptible to ambient interference. In light of this, a novel capacitive electrode was developed as an effective way to reduce the interference effect. This was done by simply introducing the capacitive elector in series with a 1 pF capacitor, and the 60 Hz common mode noise induced by AC power lines was cancelled using a capacitive right leg (CRL) circuit. The proposed electrode did as expected outperform two counterparts in terms of SNR, and particularly gave an up to 99.8% correlation between RRIs extracted from an ECG and a CECG signal, a figure far beyond 52% and 63% using the two counterparts. This capacitive electrode was originally designed for long-term noncontact monitoring of heart rate, and hopefully can be integrated to portable devices for other medical care services in the near future.

A front-end for biopotential sensing in wearable medical devices has been recently proposed which is claimed to provide 100 GOinput impedance by manually matching two resistor pairs in a positive- and a negative-feedback loop around an operationalamplifier (op amp); the cost being that the equivalent input noise voltage doubles with respect to a simple non-inverting amplifier.The ECG acquired with capacitive (sic) electrodes through a cotton shirt is presented as a proof of the performance of theproposed circuit. It turns out, however, that the analysis ignores op amp’s input capacitance hence the effort to achieve a very highinput resistance seems futile. Further, cotton is highly hygroscopic hence not an appropriate dielectric, so that there is no proofthat the electrodes tested were actually capacitive. This comment addresses these two problems and some additional conceptualand methodological inaccuracies found in the paper.

Foot impedance plethysmography was implemented using two types of electrodes (dry and capacitive) and sole force sensors. The latter are commonly used for assessing diabetic foot ulcers (DFU). For impedance plethysmography, a tetrapolar configuration has been used with three different plantar setups: four skin contact electrodes, four capacitive contact electrodes and two Force Sensing Resistors (FSRs). In this work, FSRs have been considered as possible capacitive electrodes because the top substrate contains interdigitating conductive electrodes and a semiconductive polymer. All the measurements have been performed using a 1 mA/10 kHz excitation current and have been tried under the feet of a standing person to detect impedance plethysmography signals. Contact electrodes allow a good cardiac pulse signal while capacitive contact through the socks features mains interferences. Force sensing resistors with their force-dependent resistance in parallel to the capacitive coupling, were not able to detect cardiac pulse. But promising results can be anticipated from these findings provided higher frequencies are used and larger sensor areas to help detect altered skin states in diabetic foot.

The possibility of creating capacitive electrodes for cardiography with detuning from the skin-electrode capacitance influence was studied in the paper. Electrodesathematical models and electrocardiogram signals recording scheme were developed in OrCAD, field experiments were conducted.

Toward understanding brain functionality, high channel count ECoG arrays enable expanding the resolution and/or physical scope of neural recordings. For fully implanted ECoG arrays, one limiting factor to scaling channel count is the size of the front-end recording electronics, which is dominated by the coupling capacitor needed at every recording channel. This paper presents an ECoG array with coupling capacitors fabricated into the electrodes that significantly reduces the area required for recording electronics and thus enables scaling to higher channel counts. Two different fabrication procedures were explored to form 4x4 arrays of 8 pF capacitor-embedded electrodes utilizing a stack of Cu, Ta2O5, and Ti/Au on a flexible substrate. Several in vivo experiments were performed on an adult rat, and physiologically evoked activity was successfully observed for shoulder and hindlimb tapping as well as for whisker deflection.

This comment seeks to point out that the timely review of capacitive biopotential measurements by Sun and Yu needs a clearer definition of capacitive electrodes that enables a more enlightening comparison of capacitive and dry conductive electrodes, which are two alternatives to wet electrodes for long-term applications. This, added to the ambiguous terminology in the description of system architectures, the oversight of some published results, and some potentially contradictory statements, makes the review inappropriate for the uninformed newcomer in spite of the large amount of references compiled and their broad scope.

Rat electrocardiography (ECG) is frequently used in biomedical research as a model for exploring heart function in a wide variety of experimental conditions. Subcutaneous ECG is a common approach to record rat heart rhythm using implanted needle electrodes to sense the rat ECG signals with the animal under deep anesthesia. However, such an invasive measurement could cause inconvenience due to cumbersome animal preparation, and the anesthetics are likely to interfere with the autonomic regulation of cardiac rhythm. Most studies used the galvanic contact between animal limb and electrode sensing surface to record cardiac signals from small animals. However, the non-contact approach of capacitive ECG sensing for small laboratory animals has not been extensively investigated. This study aims to develop a non-contact ECG system to promote the ECG measurement of laboratory animals for biomedical research. The method utilizes the capacitive coupling technique to detect cardiac signals in awake rats (R-wave amplitude of only 0.2 mV) through a non-conductive layer. The proposed system generates non-contact ECG signals with distinguishable R-peaks at a limb-electrode capacitance above 8.5 pF and maximum through-thickness of the non-conductive layer of 0.4 mm for heart rate assessment. In conclusion, this study provides non-contact ECG monitoring based on capacitive electrodes to improve the throughput of ECG measurement procedures for biomedical research and establish a lower bound of coupling capacitance for non-contact application to heart rate. The new method is ideally suited for the rapid evaluation of autonomic regulation of heart rhythm in awake laboratory small animals.

Water pollution and freshwater scarcity are two of the most important environmental problems faced by human around the globe in the 21st century. Capacitive deionization (CDI), as a promising electrochemical water treatment technology, has attracted large attention over the past decade for the facile removal of ions from water with the advantages of environmental friendliness, cost effectiveness, low energy consumption, and convenient electrode regeneration. Enormous progress has been made in the CDI research field and now CDI encompasses various cell architectures assembled with either capacitive electrodes or battery electrodes. These scientific advances are accompanied by a diverse application of CDI-based technologies. This work is intended to summarize the versatile applications of CDI and highlight the representative achievements in each of the applications primarily covering water desalination, water purification, water disinfection, resource recovery and synergistic combination with other technologies. Emerging application areas of CDI such as energy harvesting and CO2 capture are also presented. Lastly, the challenges and future outlook for CDI practical applications are discussed. This work should be of value in promoting CDI-based technologies to develop into a competitive option for coping with multiple water or energy-related issues.

In this paper, a three-dimensional physical model for the capacitive measurement in an insulin pen used by diabetic persons has been developed. To this purpose, ANSYS Maxwell 3D software has been used to faithfully model an insulin pen and numerically assess the electrode capacitance. A configuration with four electrodes, of given dimensions for their thickness and length, has been chosen for the cap. Consequently, information on the capacitance values between face-to-face electrodes has been obtained. This model can be used to predict the value of the electrode capacitance in many different situations imagined by the designer.

Solar Dynamics Observatory (SDO) is imaging the Sun in many wavelengths near simultaneously and with a resolution ten times higher than the average high-definition television. In this paper we describe our innovative systems approach to the design of the CCD cameras for two of SDO’s remote sensing instruments, the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI). Both instruments share use of a custom-designed 16 million pixel science-grade CCD and common camera readout electronics. A prime requirement was for the CCD to operate with significantly lower drive voltages than before, motivated by our wish to simplify the design of the camera readout electronics. Here, the challenge lies in the design of circuitry to drive the CCD's highly capacitive electrodes and to digitize its analogue video output signal with low noise and to high precision. The challenge is greatly exacerbated when forced to work with only fully space-qualified, radiation-tolerant components. We describe our systems approach to the design of the AIA and HMI CCD and camera electronics, and the engineering solutions that enabled us to comply with both mission and instrument science requirements.

The prototype of a capacitive ECG measurement device with purely passive signal transmission between electrodes and differential amplifier is presented. This design is intended to improve transmission symmetry and thus common-mode rejection. The feasibility of the approach is demonstrated by measurements with different materials between body surface and electrodes. The ECG module shall be incorporated in a mobile sensor platform in the form of a plaster for the monitoring of chronic diseases.

Cardiac diseases are still most widely spread in all regions of the world. And more and more devices are invented to satisfy increasing requirements of the patients. One of the perspective technologies in cardiac diagnostics is capacitive sensing ECG electrodes. This article describes a study of the properties of electrocardiographic capacitive electrodes PS25255 from Plessey Semiconductors for portable systems as well as some undocumented parameters of these sensors. We developed special cardiograph using Plessey's electrodes and applied to the number of patients with ischemic heart disease. We paid our attention mostly to the correct transition of the ST segment as it has critical impact on the diagnostics of ischemic heart disease.

As it was earlier described, capacitive electrodes could be widely used in electrocardiography, especially, in the state-of-the-art personal devices as they employ major advantages of these sensors. But such a way of electrocardiogram measurement usually generates quite noisy and unstable signals, which respectively must be processed with some anti-jamming algorithm. At the same time algorithm developers must take into account low computing power of portable personal devices, so designed methods must be “light” and “fast”. Such an algorithm is developed by authors and is further described in this paper.

Further investigations are presented into the capacitive imaging (CI) technique for application to NDE. A two-dimensional finite element method is employed to simulate the electric field distribution from capacitive electrodes and how them, interact with samples. Possible probe designs and the effects of design parameters on probe performance are also evaluated. Results from various samples, including insulators and metals, are presented to illustrate the range of application of the technique.

Capacitive electrodes allow to pick-up biopotentials through a dielectric layer, without using electrolytes. However, this technique is vulnerable to electric-field interference, mainly to common mode voltages produced by the 50 Hz power-line. A fully Capacitive Driven Right Leg (CDRL) circuit is proposed to reduce the patient common mode voltage vCM. The design of this circuit takes into account several factors as electrode impedance, stray coupling capacitances and amplifier transfer function response. All these parameters are addressed to ensure the circuit’s stability in most biopotential acquisition scenarios. Monte Carlo analyses were performed to find the worst conditions, resulting in a maximum CDRL gain between 70 and 80 dB. The CDRL was implemented as an independent block that can be used for different applications such as ECG, EMG or EEG. Several experimental results are presented, showing good quality recordings even using SE amplifiers, an appropriate approach for multichannel acquisition systems., Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señales

An unobtrusive measurement system for night-time heart rate (HR) monitoring is presented. The system uses capacitive electrodes that do not require galvanic skin contact, thus allowing user to wear clothes while being monitored. The electrodes are located transversely on the bed and the electrocardiographic signals are measured between each electrode and a common reference. The signals are then combined in order to remove the common mode move-ment artifacts and the best one is selected for HR detection.

The roots of electrocardiography (ECG) date back to more than 100 years. Since those times, it has developed into one of the most useful and ubiquitously applied diagnostic tools. It offers the possibility to record and analyze the electrical excitation process of the heart noninvasively by applying electrodes to the surface of the body and by suitably processing the signals using appropriate amplifiers, filters, recorders, and/or computers. By comparison to the regular pattern of ECG, pathophysiological processes and pathological states within the heart may be detected. ECG records the difference of potentials between standardized sites on the body surface, routinely termed the Einthoven-, Goldberger-, and Wilson-lead systems. Ongoing research focuses on noncontact ECG using capacitive electrodes.

Recent interest in mobile-based healthcare has driven significant demands on researching non-contact electrodes for electrocardiogram (ECG) measurement. While the conductive gel achieves the requirement in making a good contact between the electrodes and skin, several problems result. A gel-free, non-contact electrode based on capacitive coupling theory was present in this paper, which was integrated on the print circuit board (PCB). The experimental results showed that clear ECG signals could be acquired in the laboratory conditions by coupling the electrodes to the chest of patients through cotton belts.

Background Electrocardiography (ECG) requires the application of electrodes to the skin and often necessitates undressing. Capacitively coupled electrodes embedded in a normal chair would be a rational alternative for ECG screening. We evaluated the reliability and accuracy of ECG electrodes imbedded in a chair cushion. Methods Two independent clinicians compared ECG recordings obtained using skin electrodes with recordings obtained using capacitively coupled electrodes that were embedded in a chair cushion in an anesthesiology premedication room, a cardiology outpatient ward, and a cardiology day ward. We analyzed the data to compare the sensitivity and specificity for the diagnosis of cardiac arrhythmias. Results ECG recordings were obtained from 107 patients. Heart rate was accurately measured using the capacitively coupled electrodes, but motion artifacts made the identification of P and T waves unreliable. Signal quality was poor for patients with low body weight, patients wearing clothing containing mixed fibers, and patients wearing sweaty shirts. Conclusions Heart rate was accurately measured, and some cardiac arrhythmias were correctly diagnosed using capacitive ECG electrodes. Capacitive electrodes embedded into an examination chair are a promising tool for preoperative screening. Improved artifact reduction algorithms are needed before capacitive electrodes will replace skin electrodes.

Applications for capacitive ECG measurement that have been demonstrated range from clinical applications like body surface potential mapping to monitoring devices for personal health care. One common drawback in all systems is the susceptibility to motion artefacts caused by relative movement between the capacitive electrodes and the patient. In this paper we describe the setup and experiments that were used to verify the model that simulates time domain behavior of a capacitive electrode. Finally, we show that artefact correction is possible for real world capacitive ECG signals using this model, even for motion artefacts that are within the ECG spectrum.

This paper presents the first results about the acceptance of a capacitive ECG measurement system on the clinicians as well as on the patient side. In a clinical study an ECG measurement system with capacitively coupled electrodes was tested against a conventional reference ECG. The whole setup including study design, description of the measurement and clinical setup as well as the results about acceptance and first diagnostic are presented and the use in different application scenarios is discussed.

This publication describes a measurement system that obtains an electrocardiogram (ECG) by capacitively coupled electrodes. Fordemonstration purposes, this measurement system was integrated into an off-the-shelf office chair (so-called “Aachen SmartChair”).Whereas in usual clinical applications adhesive, conductively-coupled electrodes have to be attached to the skin, the described system is able to measure an ECG without direct skin contact through the cloth. A wireless communication module was integrated for transmitting theECG data to a PC or to an ICU patient monitor. For system validation, a classical ECG with conductive electrodes and an oxygensaturation signal (SpO2) were obtained simultaneously. Finally, system-specific problems of the presented device are discussed.

A prototype resistivity probe using capacitive electrodes has been built under a collaborative project funded jointly by the Geological Survey of Canada (GSC) and IFG Corporation, a Canadian manufacturer of borehole geophysical instrumentation. The GSC carried out field tests at its borehole test facilities in Ottawa and at the New Calumet massive sulphide deposit in Quebec. Results indicate that the capacitive technique is sensitive in the resistivity range 10010,000 ohm-m and compares well with galvanically and inductively measured resistivities. Field tests were also carried out for several transmitter-receiver spacings and in plastic-cased fluidfilled boreholes. Capacitive resistivity logs acquired in a plastic-cased borehole are almost identical to those acquired in the same but uncased borehole. Therefore, capacitive resistivity logs promise to be valuable for use in environmental applications where boreholes drilled in unconsolidated sediments are often plastic-cased.

Capacitive heating is widely used in hyperthermic treatment of human malignancies. However, the pain on the body surface or thermoesthesia in the subcutaneous fatty layer may prevent an elevation of temperature in the tumors. Impedance matching is improved by a subtrap method entailing the application of two copper plates (10 x 850 x 0.06 mm) as a subtrap circuit to each of two capacitive electrodes. In a clinical trial the Tmax, Tave, Tmin for the subtrap method were all higher in comparison with those for the conventional technique (42.5 +/- 0.7 degrees C, 41.9 +/- 1.0 degrees C, 41.3 +/- 1.1 degrees C vs. 41.1 +/- 1.5 degrees C, 40.6 +/- 1.3 degrees C, 40.0 +/- 1.3 degrees C). Although the maximal radiofrequency (RF) power applied to patients was higher with the subtrap method (875 +/- 189 W vs. 763 +/- 200 W), the incidence of surface pain was reduced dramatically. It is concluded that the subtrap method substantially improves the RF capacitive heating of deep-seated tumors.

The authors have been developing a fast 2D /3D resistivity imaging system using multi-channel capacitive electrodes. The capacitive electrode enables moving data acquisition and improves the field productivity considerably, because it does not require the direct contact with the ground.

Stray electric and magnetic fields have been measured near to therapeutic and surgical diathermy equipment for many different treatments. The highest field strengths are associated with continuous wave (cw) 27 MHz therapeutic diathermy equipment for which fields above national reference levels extend for 1 m from the electrodes and cables. The extent of the fields does not vary substantially with the type of treatment being performed. Recommendations that operators remain 1.0 m from cw therapeutic diathermy equipment, 0.5-0.8 m from pulsed treatments with capacitive electrodes and 0.2 m from pulsed inductive applicators can be applied to restrict exposure for any treatment with each type of unit. In a proposed European Community (EC) directive, action levels similar in magnitude to the reference levels are used to trigger requirements for assessments of hazard, measures to reduce exposure and personnel training. Assessments and appropriate recommendations of measures to reduce exposure can be linked to the type of equipment. Fields associated with electrosurgical units operating at frequencies of 0.3-0.5 MHz only approached reference levels within 20-30 cm of the cables, and because of the relatively short durations of the emissions, precautions were considered unnecessary with the units tested.

We report on the development and characterization of high performance supercapacitor electrodes synthesized using electrophoretic deposition of graphene, upon which the poly(pyrrole)-layer was electropolymerised. The highly capacitive electrode had a specific capacitance of 1510 F g(-1), area capacitance of 151 mF cm(-2) and volume capacitance of 151 F cm(-3) at 10 mV s(-1).

Reports the investigation of the discharge current and voltage in longitudinal KrF lasers with internal and external capacitive electrodes. Laser action in F2:Kr:He mixtures in a capacitively coupled discharge was observed with output energies up to 200 mu J and 0.1% efficiency in a discharge tube with diameter 2 mm, length 35 cm and a driving voltage of 84 kV. Factors which influence the operating period were investigated. A maximum lifetime of 104 shots for 3 l of gas mixture was obtained.

Background Electrocardiogram (ECG) assessment plays a crucial role in patients presenting with chest pain and suspected acute coronary syndrome (ACS). In a pilot study, we previously evaluated a capacitive ECG system (cECG) as a novel ECG technique for a fast and simple ECG assessment in patients with ST-elevation myocardial infarction (STEMI). In a next step, the sensitivity and specificity of this novel ECG technique have to be assessed in patients with ACS. Hypothesis The Fast Infarction Diagnosis ECG Trial (FIDET) is a prospective, bi-center, observer-blinded noninferiority study to evaluate the cECG compared to the conventional ECG (kECG) in the clinical practice for ECG assessment in consecutive patients presenting with suspected ACS. Methods In 250 patients who were admitted to the hospital, because of an ACS [including STEMI and non-ST-elevation acute coronary syndrome (NSTE-ACS)], both a kECG and a cECG recording were performed within a time lag of less than 10 min. End points The primary end point will be sensitivity and specificity of the cECG compared to the kECG in diagnosing a STEMI with a margin of noninferiority of 7.5 %. Secondary end points include sensitivity and specificity of the cECG compared to the kECG in diagnosing an NSTE-ACS, safety of the cECG system (adverse event, serious adverse event and suspected unexpected serious adverse reaction), parameters of the ECG measurement (PQ-interval, QT-interval, ST-amplitude and heart rate) and measurement duration of the two methods. Conclusion FIDET is designed as a noninferiority study to show that a novel cECG system is suitable for the diagnosis of myocardial infarction in the clinical context and might even have benefits, for example by offering a faster and easier ECG assessment.

The technique of capacitive electrocardiography (cECG) is very promising in a flexible manner. Already integrated into several everyday objects, the single lead cECG system has shown that easy-to-use measurements of electrocardiograms are possible without difficult preparation of the patients. Multi-channel cECG systems enable the extraction of ECG signals even in the presence of coupled interferences, due to the additional redundant information. Thus, this paper presents challenges for electronic hardware design to build on developments in recent years, going from the one-lead cECG system to multi-channel systems in order to provide robust measurements - e.g. even while driving an automobile.

Electrodialysis-related technologies keep spreading in multiple fields, among which water desalination still plays a major role. A new technology that has not yet been thoroughly investigated is capacitive electrodialysis (CED), which couples the standard ED with capacitive electrodes. CED has a number of advantages such as removal of toxic products and system simplification. Little mention is made of this technology in the literature and, to the best of our knowledge, no modelling works have ever been presented. In this work, the CED process has been studied through experiments and modelling. A CED model is presented for the first time. With a simple calibration based on macroscopic membrane properties and the characterisation of electrode behaviour, the model is able to simulate the dynamics of simple as well as more complex layouts. An original experimental characterisation of electrodes is presented, showing how the collected data can be implemented into the model. After a successful validation with experimental data, dynamic simulations of a single pass CED unit have been performed with the aim of assessing the effect of different capacitive electrode properties on process performance. Results show how the impact of these properties is different depending on the number of cell pairs.