An Approach to Evaluate Electromagnetic Interference with a Wearable ECG at Frequencies below 1MHz
01 Aug 2015-IEICE Transactions on Communications (The Institute of Electronics, Information and Communication Engineers)-Vol. 98, Iss: 8, pp 1606-1613
About: This article is published in IEICE Transactions on Communications.The article was published on 2015-08-01. It has received 9 citations till now. The article focuses on the topics: Electromagnetic interference & Wearable computer.
Citations
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TL;DR: It is shown that the authors' proposed circuit structure with the third electrode directly connected to signal ground can provide an effect on common mode noise reduction similar to the usual drive-right-leg circuit, and a sufficiently good acquisition performance of ECG signals.
Abstract: Wearable electrocardiogram (ECG) is attracting much attention in daily healthcare applications, and human body communication (HBC) technology provides an evident advantage in making the sensing electrodes of ECG also working for transmission through the human body. In view of actual usage in daily life, however, non-contact electrodes to the human body are desirable. In this Letter, the authors discussed the ECG circuit structure in the HBC-based wearable ECG for removing the common mode noise when employing non-contact capacitive coupling electrodes. Through the comparison of experimental results, they have shown that the authors' proposed circuit structure with the third electrode directly connected to signal ground can provide an effect on common mode noise reduction similar to the usual drive-right-leg circuit, and a sufficiently good acquisition performance of ECG signals.
15 citations
TL;DR: In this study, the authors quantitatively evaluated the EMI on wearable ECG for 6.8 MHz wireless power transfer system using electromagnetic field analysis technique and circuit simulation or measurement to derive the interference voltage at the wearableECG output.
Abstract: The increasing ageing population is leading to a wide-scale demand for health-state monitoring by a wireless body area network (BAN). Wireless BAN needs each vital sensor to act as a wearable device for collecting blood pressure, electrocardiogram (ECG), electroencephalogram and so on in daily life. On the other hand, wireless power transfer is also getting into our daily life because of its convenience, which suggests a potential electromagnetic interference (EMI) problem on the wearable devices in healthcare and medical BAN. In this study, the authors quantitatively evaluated the EMI on wearable ECG for 6.8 MHz wireless power transfer system. They employed electromagnetic field analysis technique to derive the common-mode voltage between the human body with a wearable ECG and the ground plane, and circuit simulation or measurement to derive the interference voltage at the wearable ECG output. The result first time gave a quantitative evaluation for EMI of wireless power transfer on wearable ECG. The approach is also available to be applied to EMI evaluation of other wearable devices in healthcare or medical applications.
13 citations
Cites methods from "An Approach to Evaluate Electromagn..."
...In this study, we employ a two-step approach [8] to evaluate the EMI level at the wearable ECG for a typical 6....
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TL;DR: The authors found that the interference voltage generated at the wearable ECG can be effectively reduced to a sufficient small level by a circuit with cadmium sulphide photo-resistors.
Abstract: Wearable electrocardiogram (ECG) is attracting much attention for monitoring heart diseases in healthcare and medical applications. However, an imbalance usually exists between the contact resistances of sensing electrodes, so that a common mode noise caused by external electromagnetic field can be converted into the ECG detection circuit as a differential mode interference voltage. In this study, after explaining the mechanism of how the common mode noise is converted to a differential mode interference voltage, the authors propose a circuit with cadmium sulphide photo-resistors for cancelling the imbalance between the contact resistances and confirm its validity by simulation experiment. As a result, the authors found that the interference voltage generated at the wearable ECG can be effectively reduced to a sufficient small level.
12 citations
TL;DR: A comparison between the ESD test results by using the immunity test system and the result for a real human body found a high similarity between them, which suggests that the proposed immunityTest system is feasible for various immunity tests in wearable devices.
Abstract: In this study, we developed an immunity test system for wearable devices used for healthcare or assistance to people with disabilities. The immunity test system consists of a pseudo biosignal generator for generating various vital signals such as electrocardiogram or electromyography and a bioequivalent gel phantom for simulating a part of the human body. As an application to the electrostatic discharge (ESD) immunity test for a myoelectric artificial hand, we used the pseudo biosignal generator to generate various myoelectric signals and confirmed a high correlation between the generated and the real myoelectric signals. We then applied this system to the IEC61000-4-2 specified ESD test. Through a comparison between the ESD test results by using the immunity test system and the result for a real human body, we found a high similarity between them, which suggests that the proposed immunity test system is feasible for various immunity tests in wearable devices.
9 citations
03 Jun 2019
TL;DR: A novel design of biosignal acquisition circuit based on canceling the imbalance between contact resistances of detection electrodes is proposed and it is indicated that the design could realize a common-mode rejection of as high as 200 dB in experimental condition, which is better than the simulated DRL circuit.
Abstract: Common-mode (CM) noise is a primary interference to biological signal (biosignal) detection systems but is hardly solved with passive filtering. Conventionally, a driven-right-leg (DRL) circuit is employed to drive down the CM noise level. In this paper, we proposed a novel design of biosignal acquisition circuit based on canceling the imbalance between contact resistances of detection electrodes and made a comparison with the DRL circuit. We first theoretically analyzed how it works in rejecting the CM noise. Then we conducted circuit simulation and the result indicates that our design could realize a common-mode rejection of as high as 200 dB in experimental condition, which is better than the simulated DRL circuit.
1 citations
Cites background from "An Approach to Evaluate Electromagn..."
...There is always an imbalance of impedance at the attaching part, which allows the common-mode (CM) noise converting into a differential mode (DM) interference voltage [3,4]....
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References
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TL;DR: The developed adult female model is the first of its kind in the world and both are the first Asian voxel models (representing average Japanese) that enable numerical evaluation of electromagnetic dosimetry at high frequencies of up to 3 GHz.
Abstract: With advances in computer performance, the use of high-resolution voxel models of the entire human body has become more frequent in numerical dosimetries of electromagnetic waves. Using magnetic resonance imaging, we have developed realistic high-resolution whole-body voxel models for Japanese adult males and females of average height and weight. The developed models consist of cubic voxels of 2 mm on each side; the models are segmented into 51 anatomic regions. The adult female model is the first of its kind in the world and both are the first Asian voxel models (representing average Japanese) that enable numerical evaluation of electromagnetic dosimetry at high frequencies of up to 3 GHz. In this paper, we will also describe the basic SAR characteristics of the developed models for the VHF/UHF bands, calculated using the finite-difference time-domain method.
732 citations
"An Approach to Evaluate Electromagn..." refers methods in this paper
...anatomical magnetic resonance imaging data [12], and the finite difference time domain (FDTD) method was adopted as the numerical EM field analysis tool in view of its flexibility in modeling complex human body shapes....
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TL;DR: A review of the history of wireless power transfer and its recent developments is given to show how such technologies can be applied to sensor networks and address their energy constraints.
Abstract: Energy constraints are widely regarded as a fundamental limitation of wireless and mobile devices. For sensor networks, a limited lifetime due to battery constraint poses a performance bottleneck and barrier for large scale deployment. Recently, wireless power transfer has emerged as a promising technology to address energy and lifetime bottlenecks in a sensor network. In this article, we give a review of the history of wireless power transfer and describe its recent developments. We show how such technologies can be applied to sensor networks and address their energy constraints.
473 citations
"An Approach to Evaluate Electromagn..." refers background in this paper
...In fact, near the ECG signal frequencies, there are many frequency bands below 1 MHz being used for not only the commercial power supply, but also broadcast, electronic security check, as well as wireless power transfer [8], [9]....
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TL;DR: A comprehensive review of existing technological solutions for wireless power transfer used in electric vehicle battery chargers is given in this article, where the concept of each solution is thoroughly reviewed and the feasibility is evaluated considering the present limitations in power electronics technology, cost and consumer acceptance.
Abstract: In this study, a comprehensive review of existing technological solutions for wireless power transfer used in electric vehicle battery chargers is given. The concept of each solution is thoroughly reviewed and the feasibility is evaluated considering the present limitations in power electronics technology, cost and consumer acceptance. In addition, the challenges and advantages of each technology are discussed. Finally, a thorough comparison is made and a proposed mixed conductive/wireless charging system solution is suggested to solve the inherent existing problems.
370 citations
"An Approach to Evaluate Electromagn..." refers background in this paper
...In fact, near the ECG signal frequencies, there are many frequency bands below 1 MHz being used for not only the commercial power supply, but also broadcast, electronic security check, as well as wireless power transfer [8], [9]....
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TL;DR: This sensor system combined an appropriate wireless protocol for data communication with capacitive ECG signal sensing and processing with small capacitive electrodes integrated into a cotton T-shirt together with a signal processing and transmitting board on a two-layer standard printed circuit board design technology.
Abstract: Ubiquitous vital signs sensing using wireless medical sensors are promising alternatives to conventional, in-hospital healthcare systems. In this work, a wearable ECG sensor is proposed. This sensor system combined an appropriate wireless protocol for data communication with capacitive ECG signal sensing and processing. The ANT protocol was used as a low-data-rate wireless module to reduce the power consumption and size of the sensor. Furthermore, capacitive ECG sensing is a simple technique that avoids direct contact with the skin and provides maximum convenience to the user. In our work, small capacitive electrodes were integrated into a cotton T-shirt together with a signal processing and transmitting board on a two-layer standard printed circuit board design technology. The entire system has small size, is thin, and has low power consumption compared to recent ECG monitoring systems. In addition, appropriate signal conditioning and processing were implemented to remove motion artifacts. The acquired ECG signals are comparable to ones obtained using conventional glued-on electrodes, and are easily read and interpreted by a cardiologist.
319 citations
"An Approach to Evaluate Electromagn..." refers background in this paper
...It should be noted that the ECG detection circuit in our wearable ECG has a typical structure as introduced in [4]....
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...By attaching such devices to patients or elderly people, the vital signal data can be automatically collected, and then forwarded to medical staff in a hospital or medical center for medical and health care administration and applications [1]–[4]....
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TL;DR: A multichannel instrumentation amplifier, developed to be used in a miniature universal eight-channel amplifier module, is described and the results of this study are applied to miniature, universal, eight- channel amplifier modules, manufactured with thick-film production techniques.
Abstract: A multichannel instrumentation amplifier, developed to be used in a miniature universal eight-channel amplifier module, is described. After discussing the specific properties of a bioelectric recording, the difficulties of meeting the demanded specifications with a design based on operational amplifiers are reviewed. Because it proved impossible to achieve the demanded combination of low noise and low power consumption using commercially available operational amplifiers, an amplifier equipped with an input stage with discrete transistors was developed. A new design concept was used to expand the design to a multichannel version with an equivalent input noise voltage of 0·35 μV RMS in a bandwidth of 0·1–100 Hz and a power consumption of 0·6 mW per channel. The results of this study are applied to miniature, universal, eight-channel amplifier modules, manufactured with thick-film production techniques. The modules can be coupled to satisfy the demand for a multiple of eight channels. The low power consumption enables the modules to be used in all kinds of portable and telemetry measurement systems and simplifies the power supply in stationary measurement systems.
281 citations
"An Approach to Evaluate Electromagn..." refers background in this paper
...As for Cs, the capacitance between the circuit ground and the earth ground, in view of that the circuit is attached to the human body, we assumed it between 20 pF and 200 pF [7]....
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...For wearable health care devices such as a wearable ECG, the EMI problem is mainly focused on the interference in commercial power frequency bands [6], [7]....
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