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Yu S, Sun X, Liu J, Li S. OECT - Inspired electrical detection. Talanta 2024; 275:126180. [PMID: 38703480 DOI: 10.1016/j.talanta.2024.126180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Revised: 04/16/2024] [Accepted: 04/27/2024] [Indexed: 05/06/2024]
Abstract
Organic Electrochemical Transistors (OECTs) are integral in detecting human bioelectric signals, attributing their significance to distinct electrochemical properties, the utilization of soft materials, compact dimensions, and pronounced biocompatibility. This review traverses the technological evolution of OECT, highlighting its profound impact on non-invasive detection methodologies within the biomedicalfield. Four sensor types rooted in OECT technology were introduced: Electrocardiogram (ECG), Electroencephalogram (EEG), Electromyography (EMG), and Electrooculography (EOG), which hold promise for integration into wearable detection systems. The fundamental detection principles, material compositions, and functional attributes of these sensors are examined. Additionally, the performance metrics and delineates viable optimization strategies for assorted physiological electrical detection sensors are discussed. The overarching goal of this review is to foster deeper insights into the generation, propagation, and modulation of electrophysiological signals, thereby advancing the application and development of OECT in medical sciences.
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Affiliation(s)
- Shixin Yu
- School of Automation Engineering, Northeast Electric Power University, Jilin, 132012, China
| | - Xiaojun Sun
- School of Automation Engineering, Northeast Electric Power University, Jilin, 132012, China
| | - Jingjing Liu
- School of Automation Engineering, Northeast Electric Power University, Jilin, 132012, China.
| | - Shuang Li
- Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin, 300072, China.
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2
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Joutsen A, Cömert A, Kaappa E, Vanhatalo K, Riistama J, Vehkaoja A, Eskola H. ECG signal quality in intermittent long-term dry electrode recordings with controlled motion artifacts. Sci Rep 2024; 14:8882. [PMID: 38632263 PMCID: PMC11024137 DOI: 10.1038/s41598-024-56595-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 03/08/2024] [Indexed: 04/19/2024] Open
Abstract
Wearable long-term monitoring applications are becoming more and more popular in both the consumer and the medical market. In wearable ECG monitoring, the data quality depends on the properties of the electrodes and on how they interface with the skin. Dry electrodes do not require any action from the user. They usually do not irritate the skin, and they provide sufficiently high-quality data for ECG monitoring purposes during low-intensity user activity. We investigated prospective motion artifact-resistant dry electrode materials for wearable ECG monitoring. The tested materials were (1) porous: conductive polymer, conductive silver fabric; and (2) solid: stainless steel, silver, and platinum. ECG was acquired from test subjects in a 10-min continuous settling test and in a 48-h intermittent long-term test. In the settling test, the electrodes were stationary, whereas both stationary and controlled motion artifact tests were included in the long-term test. The signal-to-noise ratio (SNR) was used as the figure of merit to quantify the results. Skin-electrode interface impedance was measured to quantify its effect on the ECG, as well as to leverage the dry electrode ECG amplifier design. The SNR of all electrode types increased during the settling test. In the long-term test, the SNR was generally elevated further. The introduction of electrode movement reduced the SNR markedly. Solid electrodes had a higher SNR and lower skin-electrode impedance than porous electrodes. In the stationary testing, stainless steel showed the highest SNR, followed by platinum, silver, conductive polymer, and conductive fabric. In the movement testing, the order was platinum, stainless steel, silver, conductive polymer, and conductive fabric.
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Affiliation(s)
- Atte Joutsen
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland.
- Finnish Cardiovascular Research Center, Tampere, Finland.
- Department of Medical Physics, Tampere University Hospital, Tampere, Finland.
| | - Alper Cömert
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Emma Kaappa
- Faculty of Engineering and Natural Sciences, Tampere University, Tampere, Finland
| | - Kirsi Vanhatalo
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | | | - Antti Vehkaoja
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
- Finnish Cardiovascular Research Center, Tampere, Finland
| | - Hannu Eskola
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
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3
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Warnecke JM, Wang J, Cakir T, Spicher N, Ganapathy N, Deserno TM. Registered report protocol: Developing an artifact index for capacitive electrocardiography signals acquired with an armchair. PLoS One 2021; 16:e0254780. [PMID: 34320002 PMCID: PMC8318277 DOI: 10.1371/journal.pone.0254780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Accepted: 07/04/2021] [Indexed: 11/18/2022] Open
Abstract
Continuous monitoring of an electrocardiogram (ECG) in private diagnostic spaces such as vehicles or apartments allows early detection of cardiovascular diseases. We will use an armchair with integrated capacitive electrodes to record the capacitive electrocardiogram (cECG) during everyday activities. However, movements and other artifacts affect the signal quality. Therefore, an artifact index is needed to detect artifacts and classify the cECG. The unavailability of cECG data and reliable ground truth information requires new recordings to develop an artifact index. This study is designed to test the hypothesis: an artifact index can be devised, which intends to estimate the signal quality of segments and classify signals. In a single-arm study with 44 subjects, we will record two activities of 11-minute duration: reading and watching television. During recording, we will capture cECG, ECG, and oxygen saturation (SpO2) with time synchronization as well as keypoint-based movement indicators obtained from a video camera. SpO2 provides additional information on the subject's health status. The keypoint-based movements indicate artifacts in the cECG. We will combine all ground truth data to evaluate the index. In the future, we aim at using the artifact index to exclude cECG segments with artifacts from further analysis. This will improve cECG technology for the measurement of cardiovascular parameters.
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Affiliation(s)
- Joana M. Warnecke
- Peter L. Reichertz Institute for Medical Informatics of TU Braunschweig and Hannover Medical School, Braunschweig, Germany
- * E-mail:
| | - Ju Wang
- Peter L. Reichertz Institute for Medical Informatics of TU Braunschweig and Hannover Medical School, Braunschweig, Germany
| | - Tolga Cakir
- Peter L. Reichertz Institute for Medical Informatics of TU Braunschweig and Hannover Medical School, Braunschweig, Germany
| | - Nicolai Spicher
- Peter L. Reichertz Institute for Medical Informatics of TU Braunschweig and Hannover Medical School, Braunschweig, Germany
| | - Nagarajan Ganapathy
- Peter L. Reichertz Institute for Medical Informatics of TU Braunschweig and Hannover Medical School, Braunschweig, Germany
| | - Thomas M. Deserno
- Peter L. Reichertz Institute for Medical Informatics of TU Braunschweig and Hannover Medical School, Braunschweig, Germany
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4
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Galli A, Peri E, Zhang Y, Vullings R, van der Ven M, Giorgi G, Ouzounov S, Harpe PJA, Mischi M. Dedicated Algorithm for Unobtrusive Fetal Heart Rate Monitoring Using Multiple Dry Electrodes. SENSORS 2021; 21:s21134298. [PMID: 34201834 PMCID: PMC8271482 DOI: 10.3390/s21134298] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 06/16/2021] [Accepted: 06/21/2021] [Indexed: 12/03/2022]
Abstract
Multi-channel measurements from the maternal abdomen acquired by means of dry electrodes can be employed to promote long-term monitoring of fetal heart rate (fHR). The signals acquired with this type of electrode have a lower signal-to-noise ratio and different artifacts compared to signals acquired with conventional wet electrodes. Therefore, starting from the benchmark algorithm with the best performance for fHR estimation proposed by Varanini et al., we propose a new method specifically designed to remove artifacts typical of dry-electrode recordings. To test the algorithm, experimental textile electrodes were employed that produce artifacts typical of dry and capacitive electrodes. The proposed solution is based on a hybrid (hardware and software) pre-processing step designed specifically to remove the disturbing component typical of signals acquired with these electrodes (triboelectricity artifacts and amplitude modulations). The following main processing steps consist of the removal of the maternal ECG by blind source separation, the enhancement of the fetal ECG and identification of the fetal QRS complexes. Main processing is designed to be robust to the high-amplitude motion artifacts that corrupt the acquisition. The obtained denoising system was compared with the benchmark algorithm both on semi-simulated and on real data. The performance, quantified by means of sensitivity, F1-score and root-mean-square error metrics, outperforms the performance obtained with the original method available in the literature. This result proves that the design of a dedicated processing system based on the signal characteristics is necessary for reliable and accurate estimation of the fHR using dry, textile electrodes.
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Affiliation(s)
- Alessandra Galli
- Department of Information Engineering, University of Padova, I-35131 Padova, Italy; (A.G.); (G.G.)
- Department of Electrical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands; (E.P.); (Y.Z.); (R.V.); (M.v.d.V.); (P.J.A.H.)
| | - Elisabetta Peri
- Department of Electrical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands; (E.P.); (Y.Z.); (R.V.); (M.v.d.V.); (P.J.A.H.)
| | - Yijing Zhang
- Department of Electrical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands; (E.P.); (Y.Z.); (R.V.); (M.v.d.V.); (P.J.A.H.)
| | - Rik Vullings
- Department of Electrical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands; (E.P.); (Y.Z.); (R.V.); (M.v.d.V.); (P.J.A.H.)
| | - Myrthe van der Ven
- Department of Electrical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands; (E.P.); (Y.Z.); (R.V.); (M.v.d.V.); (P.J.A.H.)
| | - Giada Giorgi
- Department of Information Engineering, University of Padova, I-35131 Padova, Italy; (A.G.); (G.G.)
| | | | - Pieter J. A. Harpe
- Department of Electrical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands; (E.P.); (Y.Z.); (R.V.); (M.v.d.V.); (P.J.A.H.)
| | - Massimo Mischi
- Department of Electrical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands; (E.P.); (Y.Z.); (R.V.); (M.v.d.V.); (P.J.A.H.)
- Correspondence:
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Car Seats with Capacitive ECG Electrodes Can Detect Cardiac Pacemaker Spikes. SENSORS 2020; 20:s20216288. [PMID: 33158273 PMCID: PMC7663839 DOI: 10.3390/s20216288] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/20/2020] [Accepted: 10/20/2020] [Indexed: 11/17/2022]
Abstract
The capacitive electrocardiograph (cECG) has been tested for several measurement scenarios, including hospital beds, car seats and chairs since it was first proposed. The inferior signal quality of the cECG compared to the gold standard ECG guides the ongoing research in the direction of out-of-hospital applications, where unobtrusiveness is sought and high-level diagnostic signal quality is not essential. This study aims to expand the application range of cECG not in terms of the measurement scenario but in the profile of the subjects by including subjects with implanted cardiac pacemakers. Within this study, 20 patients with cardiac pacemakers were recruited during their clinical device follow-up and cECG measurements were conducted using a seat equipped with integrated cECG electrodes. The multichannel cECG recordings of active unipolar and bipolar pacemaker stimulation were analyzed offline and evaluated in terms of Fβ scores using a pacemaker spike detection algorithm. Fβ scores from 3652 pacing events, varying from 0.62 to 0.78, are presented with influencing parameters in the algorithm and the comparison of cECG channels. By tuning the parameters of the algorithm, different ranges of Fβ scores were found as 0.32 to 0.49 and 0.78 to 0.88 for bipolar and unipolar stimulations, respectively. For the first time, this study shows the feasibility of a cECG system allowing health monitoring in daily use on subjects wearing cardiac pacemakers.
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Electrode Humidification Design for Artifact Reduction in Capacitive ECG Measurements. SENSORS 2020; 20:s20123449. [PMID: 32570924 PMCID: PMC7349487 DOI: 10.3390/s20123449] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 06/09/2020] [Accepted: 06/16/2020] [Indexed: 11/17/2022]
Abstract
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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7
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Nakamura H, Sakajiri Y, Ishigami H, Ueno A. A Novel Analog Front End with Voltage-Dependent Input Impedance and Bandpass Amplification for Capacitive Biopotential Measurements. SENSORS 2020; 20:s20092476. [PMID: 32349328 PMCID: PMC7249202 DOI: 10.3390/s20092476] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 04/20/2020] [Accepted: 04/24/2020] [Indexed: 11/16/2022]
Abstract
This paper proposes a novel analogue front end (AFE) that has three features: voltage-dependent input impedance, bandpass amplification, and stray capacitance reduction. With a view to applying the AFE to capacitive biopotential measurements (CBMs), the three features were investigated separately in a schematic and mathematical manner. Capacitive electrocardiogram (cECG) or capacitive electromyogram (cEMG) measurements using the AFE were performed in low-humidity conditions (below 35% relative humidity) for a total of seven human subjects. Performance evaluation of the AFE revealed the following: (1) the proposed AFE in cECG measurement with 1.70-mm thick clothing reduced the baseline recovery time and root mean square voltage of respiratory interference in subjects with healthy-weight body mass index (BMI), and increased R-wave amplitude for overweight-BMI subjects; and (2) the proposed AFE in cEMG measurement of biceps brachii muscle yielded stable electromyographic waveforms without the marked DC component for all subjects and a significant (p < 0.01) increase in the signal-to-noise ratio. These results indicate that the proposed AFE can provide a feasible balance between sensitivity and stability in CBMs, and it could be a versatile replacement for the conventional voltage follower used in CBMs.
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Affiliation(s)
- Hajime Nakamura
- Master’s Program in Electrical and Electronic Engineering, Graduate School of Engineering, Tokyo Denki University, Tokyo 120-8551, Japan; (H.N.); (Y.S.); (H.I.)
| | - Yuichiro Sakajiri
- Master’s Program in Electrical and Electronic Engineering, Graduate School of Engineering, Tokyo Denki University, Tokyo 120-8551, Japan; (H.N.); (Y.S.); (H.I.)
| | - Hiroshi Ishigami
- Master’s Program in Electrical and Electronic Engineering, Graduate School of Engineering, Tokyo Denki University, Tokyo 120-8551, Japan; (H.N.); (Y.S.); (H.I.)
| | - Akinori Ueno
- Department of Electrical and Electronic Engineering, Tokyo Denki University, Tokyo 120-8551, Japan
- Correspondence: ; Tel.: +81-3-5284-5404
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8
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Curry EJ, Le TT, Das R, Ke K, Santorella EM, Paul D, Chorsi MT, Tran KTM, Baroody J, Borges ER, Ko B, Golabchi A, Xin X, Rowe D, Yue L, Feng J, Morales-Acosta MD, Wu Q, Chen IP, Cui XT, Pachter J, Nguyen TD. Biodegradable nanofiber-based piezoelectric transducer. Proc Natl Acad Sci U S A 2020; 117:214-220. [PMID: 31871178 PMCID: PMC6955346 DOI: 10.1073/pnas.1910343117] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Piezoelectric materials, a type of "smart" material that generates electricity while deforming and vice versa, have been used extensively for many important implantable medical devices such as sensors, transducers, and actuators. However, commonly utilized piezoelectric materials are either toxic or nondegradable. Thus, implanted devices employing these materials raise a significant concern in terms of safety issues and often require an invasive removal surgery, which can damage directly interfaced tissues/organs. Here, we present a strategy for materials processing, device assembly, and electronic integration to 1) create biodegradable and biocompatible piezoelectric PLLA [poly(l-lactic acid)] nanofibers with a highly controllable, efficient, and stable piezoelectric performance, and 2) demonstrate device applications of this nanomaterial, including a highly sensitive biodegradable pressure sensor for monitoring vital physiological pressures and a biodegradable ultrasonic transducer for blood-brain barrier opening that can be used to facilitate the delivery of drugs into the brain. These significant applications, which have not been achieved so far by conventional piezoelectric materials and bulk piezoelectric PLLA, demonstrate the PLLA nanofibers as a powerful material platform that offers a profound impact on various medical fields including drug delivery, tissue engineering, and implanted medical devices.
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Affiliation(s)
- Eli J Curry
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269
| | - Thinh T Le
- Department of Mechanical Engineering, University of Connecticut, Storrs, CT 06269
| | - Ritopa Das
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269
| | - Kai Ke
- College of Polymer Science and Engineering, Sichuan University, Chengdu 610065, Sichuan, China
| | - Elise M Santorella
- Blood-Brain Barrier Laboratory, Department of Immunology, University of Connecticut Health Center, Farmington, CT 06030
| | - Debayon Paul
- Blood-Brain Barrier Laboratory, Department of Immunology, University of Connecticut Health Center, Farmington, CT 06030
| | - Meysam T Chorsi
- Department of Mechanical Engineering, University of Connecticut, Storrs, CT 06269
| | - Khanh T M Tran
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269
| | - Jeffrey Baroody
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269
| | - Emily R Borges
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269
| | - Brian Ko
- Department of Agricultural and Biological Engineering, Mississippi State University, Mississippi State, MS 39762
| | - Asiyeh Golabchi
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15260
| | - Xiaonan Xin
- Center for Regenerative Medicine and Skeletal Development, University of Connecticut Health Center, Farmington, CT 06030
| | - David Rowe
- Center for Regenerative Medicine and Skeletal Development, University of Connecticut Health Center, Farmington, CT 06030
| | - Lixia Yue
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030
| | - Jianlin Feng
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030
| | | | - Qian Wu
- Pathology and Laboratory Medicine, University of Connecticut Health Center, Farmington, CT 06030
| | - I-Ping Chen
- Department of Oral Health and Diagnostic Sciences, School of Dental Medicine, University of Connecticut Health Center, Farmington, CT 06030
| | - X Tracy Cui
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15260
| | - Joel Pachter
- Blood-Brain Barrier Laboratory, Department of Immunology, University of Connecticut Health Center, Farmington, CT 06030
| | - Thanh D Nguyen
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269;
- Department of Mechanical Engineering, University of Connecticut, Storrs, CT 06269
- Institute of Materials Science, University of Connecticut, Storrs, CT 06269
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9
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Castro ID, Patel A, Torfs T, Puers R, Van Hoof C. Capacitive multi-electrode array with real-time electrode selection for unobtrusive ECG & BIOZ monitoring. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2019; 2019:5621-5624. [PMID: 31947128 DOI: 10.1109/embc.2019.8857150] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Capacitively-coupled ECG (ccECG) and bioimpedance (ccBIOZ) measurements are highly sensitive to motion artefacts. This limits their use in real-life situations. This work presents an array-based system for the simultaneous acquisition of ccECG and ccBIOZ, together with a quality-based electrode scanning approach for ccECG. This allows to increase the time coverage of contactless measurements in real-life situations and reduces the impact of artefacts. This solution was evaluated on a car seat and a mattress prototype. Results show the benefit of this combined array and algorithm approach: for every body position the algorithm was able to find more than one electrode combination providing high-quality ccECG. Night-long recordings were also performed, resulting in a mean time coverage of 72.5%.
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10
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Tsukada YT, Tokita M, Murata H, Hirasawa Y, Yodogawa K, Iwasaki YK, Asai K, Shimizu W, Kasai N, Nakashima H, Tsukada S. Validation of wearable textile electrodes for ECG monitoring. Heart Vessels 2019; 34:1203-1211. [PMID: 30680493 PMCID: PMC6556171 DOI: 10.1007/s00380-019-01347-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 01/11/2019] [Indexed: 11/25/2022]
Abstract
A highly conductive textile was woven from nano-fibers coated with the PEDOT-PSS polymer. The aim of this study was to assess the usefulness of textile electrodes for ECG recording as a smart garment. Electrode textile pads and lead wires were sewn to the lining of sportswear and their tolerability to repeated washings were tested up to 150 times. The electrical conductivity of the textile electrode remained functional for up to 50 machine washes. To assess the level of motion artifacts or noise during the daily monitoring of ECG, a single lead ECG with conventional or textile electrodes was recorded during supine rest, seated rest, upright trunk rotation (i.e., twisting), and stepping movement in 66 healthy adults. A Holter system was used for data storage and analysis. ECG patterns of P, QRS, and T waves were comparable between the conventional and textile electrodes. However, the signal-to-artifact-and/or-noise ratio (SAR) during twisting was larger in the textile electrodes than in the conventional electrodes. No skin irritation was seen in the textile electrodes. The single lead textile electrodes embedded in an inner garment were usable for continuous and/or repeated ECG monitoring in daily life except during vigorous trunk movement.
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Affiliation(s)
- Yayoi Tetsuou Tsukada
- Department of Cardiovascular Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-Ku, Tokyo, 113-8603, Japan.
| | - Miwa Tokita
- Department of Cardiovascular Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-Ku, Tokyo, 113-8603, Japan
| | - Hiroshige Murata
- Department of Cardiovascular Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-Ku, Tokyo, 113-8603, Japan
| | - Yasuhiro Hirasawa
- Department of Cardiovascular Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-Ku, Tokyo, 113-8603, Japan
- Hakujikai Memorial Hospital, 5-11-1 Shikahama, Adachi-Ku, Tokyo, 123-0864, Japan
| | - Kenji Yodogawa
- Department of Cardiovascular Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-Ku, Tokyo, 113-8603, Japan
| | - Yu-Ki Iwasaki
- Department of Cardiovascular Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-Ku, Tokyo, 113-8603, Japan
| | - Kuniya Asai
- Department of Cardiovascular Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-Ku, Tokyo, 113-8603, Japan
| | - Wataru Shimizu
- Department of Cardiovascular Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-Ku, Tokyo, 113-8603, Japan
| | - Nahoko Kasai
- NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato Wakamiya Atsugi, Kanagawa, 243-0198, Japan
| | - Hiroshi Nakashima
- NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato Wakamiya Atsugi, Kanagawa, 243-0198, Japan
| | - Shingo Tsukada
- NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato Wakamiya Atsugi, Kanagawa, 243-0198, Japan
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11
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Nicolai EN, Michelson NJ, Settell ML, Hara SA, Trevathan JK, Asp AJ, Stocking KC, Lujan JL, Kozai TDY, Ludwig KA. Design Choices for Next-Generation Neurotechnology Can Impact Motion Artifact in Electrophysiological and Fast-Scan Cyclic Voltammetry Measurements. MICROMACHINES 2018; 9:E494. [PMID: 30424427 PMCID: PMC6215211 DOI: 10.3390/mi9100494] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 09/15/2018] [Accepted: 09/21/2018] [Indexed: 12/23/2022]
Abstract
Implantable devices to measure neurochemical or electrical activity from the brain are mainstays of neuroscience research and have become increasingly utilized as enabling components of clinical therapies. In order to increase the number of recording channels on these devices while minimizing the immune response, flexible electrodes under 10 µm in diameter have been proposed as ideal next-generation neural interfaces. However, the representation of motion artifact during neurochemical or electrophysiological recordings using ultra-small, flexible electrodes remains unexplored. In this short communication, we characterize motion artifact generated by the movement of 7 µm diameter carbon fiber electrodes during electrophysiological recordings and fast-scan cyclic voltammetry (FSCV) measurements of electroactive neurochemicals. Through in vitro and in vivo experiments, we demonstrate that artifact induced by motion can be problematic to distinguish from the characteristic signals associated with recorded action potentials or neurochemical measurements. These results underscore that new electrode materials and recording paradigms can alter the representation of common sources of artifact in vivo and therefore must be carefully characterized.
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Affiliation(s)
- Evan N Nicolai
- Mayo Clinic Graduate School of Biomedical Sciences, Rochester, MN 55905, USA.
| | - Nicholas J Michelson
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15213, USA.
- Department of Psychiatry, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
| | - Megan L Settell
- Mayo Clinic Graduate School of Biomedical Sciences, Rochester, MN 55905, USA.
| | - Seth A Hara
- Division of Engineering, Mayo Clinic, Rochester, MN 55905, USA.
| | - James K Trevathan
- Mayo Clinic Graduate School of Biomedical Sciences, Rochester, MN 55905, USA.
| | - Anders J Asp
- Mayo Clinic Graduate School of Biomedical Sciences, Rochester, MN 55905, USA.
| | - Kaylene C Stocking
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15213, USA.
| | - J Luis Lujan
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN 55905, USA.
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA.
| | - Takashi D Y Kozai
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15213, USA.
- Center for the Neural Basis of Cognition, University of Pittsburgh and Carnegie Mellon University, Pittsburgh, PA 15213, USA.
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA.
- NeuroTech Center of the University of Pittsburgh Brain Institute, Pittsburgh, PA 15213, USA.
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA 15213, USA.
| | - Kip A Ludwig
- Department of Bioengineering, University of Wisconsin, Madison, WI 53706, USA.
- Department of Neurological Surgery, University of Wisconsin, Madison, WI 53706, USA.
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Leonhardt S, Leicht L, Teichmann D. Unobtrusive Vital Sign Monitoring in Automotive Environments-A Review. SENSORS (BASEL, SWITZERLAND) 2018; 18:E3080. [PMID: 30217062 PMCID: PMC6163776 DOI: 10.3390/s18093080] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 08/22/2018] [Accepted: 08/30/2018] [Indexed: 01/16/2023]
Abstract
This review provides an overview of unobtrusive monitoring techniques that could be used to monitor some of the human vital signs (i.e., heart activity, breathing activity, temperature and potentially oxygen saturation) in a car seat. It will be shown that many techniques actually measure mechanical displacement, either on the body surface and/or inside the body. However, there are also techniques like capacitive electrocardiogram or bioimpedance that reflect electrical activity or passive electrical properties or thermal properties (infrared thermography). In addition, photopleythysmographic methods depend on optical properties (like scattering and absorption) of biological tissues and-mainly-blood. As all unobtrusive sensing modalities are always fragile and at risk of being contaminated by disturbances (like motion, rapidly changing environmental conditions, triboelectricity), the scope of the paper includes a survey on redundant sensor arrangements. Finally, this review also provides an overview of automotive demonstrators for vital sign monitoring.
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Affiliation(s)
- Steffen Leonhardt
- Chair for Medical Information Technology, Helmholtz-Institute for Biomedical Engineering, RWTH Aachen University, D-52076 Aachen, Germany.
| | - Lennart Leicht
- Chair for Medical Information Technology, Helmholtz-Institute for Biomedical Engineering, RWTH Aachen University, D-52076 Aachen, Germany.
| | - Daniel Teichmann
- Institute for Medical Engineering and Science (IMES), Massachusetts Institute of Technology (M.I.T.), Boston, MA 02139, USA.
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Leicht L, Skobel E, Knackstedt C, Mathissen M, Sitter A, Wartzek T, Mohler W, Reith S, Leonhardt S, Teichmann D. Capacitive ECG Monitoring in Cardiac Patients During Simulated Driving. IEEE Trans Biomed Eng 2018; 66:749-758. [PMID: 30004869 DOI: 10.1109/tbme.2018.2855661] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
OBJECTIVE This study aims to compare the informative value of a capacitively coupled electrocardiogram (cECG) to a conventional galvanic reference ECG (rECG) in patients after a major cardiac event under simulated driving conditions. Addressed research questions are the comparison and coherence of cECG and rECG by means of the signal quality, the artifact rate, the rate of assessable data for differential diagnosis, the visibility of characteristic ECG structures in cECG, the precision of ECG time intervals, and heart rate (in particular, despite possible waveform deformations due to the cardiac preconditions). METHODS In a clinical trial, cECG and rECG data were recorded from ten patients after a major cardiac event. The cECG and rECG data were blindly evaluated by two cardiologists with regard to signal quality, artifacts, assessable data for differential diagnosis, visibility of ECG structures, and ECG time intervals. The results were statistically compared. RESULTS The cECG presented with more artifacts, an inferior signal quality, and less assessable data. However, when the data were assessable, determination of the ECG interval lengths was coherent to the one obtained from the rECG. CONCLUSION When the signal quality is sufficient, the cECG yields the same informative value as the rECG. SIGNIFICANCE For certain scenarios, cECG might replace rECG systems. Hence, it is an important research question whether a similar amount of information can be obtained using a cECG system.
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14
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Hoog Antink C, Schulz F, Leonhardt S, Walter M. Motion Artifact Quantification and Sensor Fusion for Unobtrusive Health Monitoring. SENSORS 2017; 18:s18010038. [PMID: 29295594 PMCID: PMC5795602 DOI: 10.3390/s18010038] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 12/19/2017] [Accepted: 12/20/2017] [Indexed: 11/17/2022]
Abstract
Sensors integrated into objects of everyday life potentially allow unobtrusive health monitoring at home. However, since the coupling of sensors and subject is not as well-defined as compared to a clinical setting, the signal quality is much more variable and can be disturbed significantly by motion artifacts. One way of tackling this challenge is the combined evaluation of multiple channels via sensor fusion. For robust and accurate sensor fusion, analyzing the influence of motion on different modalities is crucial. In this work, a multimodal sensor setup integrated into an armchair is presented that combines capacitively coupled electrocardiography, reflective photoplethysmography, two high-frequency impedance sensors and two types of ballistocardiography sensors. To quantify motion artifacts, a motion protocol performed by healthy volunteers is recorded with a motion capture system, and reference sensors perform cardiorespiratory monitoring. The shape-based signal-to-noise ratio SNRS is introduced and used to quantify the effect on motion on different sensing modalities. Based on this analysis, an optimal combination of sensors and fusion methodology is developed and evaluated. Using the proposed approach, beat-to-beat heart-rate is estimated with a coverage of 99.5% and a mean absolute error of 7.9 ms on 425 min of data from seven volunteers in a proof-of-concept measurement scenario.
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Affiliation(s)
- Christoph Hoog Antink
- Philips Chair for Medical Information Technology, RWTH Aachen University, 52074 Aachen, Germany.
| | - Florian Schulz
- Philips Chair for Medical Information Technology, RWTH Aachen University, 52074 Aachen, Germany.
| | - Steffen Leonhardt
- Philips Chair for Medical Information Technology, RWTH Aachen University, 52074 Aachen, Germany.
| | - Marian Walter
- Philips Chair for Medical Information Technology, RWTH Aachen University, 52074 Aachen, Germany.
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Antink CH, Leonhardt S, Schulz F, Walter M. MuSeSe - A multisensor armchair for unobtrusive vital sign estimation and motion artifact analysis. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2017; 2017:857-860. [PMID: 29060007 DOI: 10.1109/embc.2017.8036959] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Unobtrusive vital sign estimation with sensors integrated into objects of everyday living can substantially advance the field of remote monitoring. At the same time, motion artifacts cause severe problems and have to be dealt with. Here, the fusion of multimodal sensor data is a promising approach. In this paper, we present an armchair equipped with capacitively coupled electrocardiogram, two types of ballistocardiographic sensors, photoplethysmographic and two high-frequency impedance sensors. In addition, a video-based sensor for motion analysis is integrated. Using a defined motion protocol, the feasibility of the system is demonstrated in a self-experimentation. Moreover, the influence of different movements on different modalities is analyzed. Finally, robust beat-to-beat interval estimation demonstrates the benefits of multimodal sensor fusion for vital sign estimation in the presence of motion artifacts.
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16
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Hoog Antink C, Leonhardt S, Walter M. A synthesizer framework for multimodal cardiorespiratory signals. Biomed Phys Eng Express 2017. [DOI: 10.1088/2057-1976/aa76ee] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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17
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Leicht L, Eilebrecht B, Weyer S, Leonhardt S, Teichmann D. Closed-Loop Control of Humidification for Artifact Reduction in Capacitive ECG Measurements. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2017; 11:300-313. [PMID: 28129182 DOI: 10.1109/tbcas.2016.2613097] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Recording biosignals without the need for direct skin contact offers new opportunities for ubiquitous health monitoring. Electrodes with capacitive coupling have been shown to be suitable for the monitoring of electrical potentials on the body surface, in particular ECG. However, due to triboelectric charge generation and motion artifacts, signal and thus diagnostic quality is inferior to galvanic coupling. Active closed-loop humidification of capacitive electrodes is proposed in this work as a new concept to improve signal quality. A capacitive ECG recording system integrated into a common car seat is presented. It can regulate the micro climate at the interface of electrode and patient by actively dispensing water vapour and monitoring humidity in a closed-loop approach. As a regenerative water reservoir, silica gel is used. The system was evaluated with respect to subjective and objective ECG signal quality. Active humidification was found to have a significant positive effect in case of previously poor quality. Also, it had no diminishing effect in case of already good signal quality.
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Kim N, Lim T, Song K, Yang S, Lee J. Stretchable Multichannel Electromyography Sensor Array Covering Large Area for Controlling Home Electronics with Distinguishable Signals from Multiple Muscles. ACS APPLIED MATERIALS & INTERFACES 2016; 8:21070-6. [PMID: 27500864 DOI: 10.1021/acsami.6b05025] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Physiological signals provide important information for biomedical applications and, more recently, in the form of wearable electronics for active interactions between bodies and external environments. Multiple physiological sensors are often required to map distinct signals from multiple points over large areas for more diverse applications. In this paper, we present a reusable, multichannel, surface electromyography (EMG) sensor array that covers multiple muscles over relatively large areas, with compliant designs that provide different levels of stiffness for repetitive uses, without backing layers. Mechanical and electrical characteristics along with distinct measurements from different muscles demonstrate the feasibility of the concept. The results should be useful to actively control devices in the environment with one array of wearable sensors, as demonstrated with home electronics.
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Affiliation(s)
- Namyun Kim
- School of Mechanical Engineering and ‡Research Institute of Solar and Sustainable Energy, Gwangju Institute of Science and Technology (GIST) , 123 Cheomdan-gwagiro, Buk-gu, Gwangju 61005, Republic of Korea
| | - Taehoon Lim
- School of Mechanical Engineering and ‡Research Institute of Solar and Sustainable Energy, Gwangju Institute of Science and Technology (GIST) , 123 Cheomdan-gwagiro, Buk-gu, Gwangju 61005, Republic of Korea
| | - Kwangsun Song
- School of Mechanical Engineering and ‡Research Institute of Solar and Sustainable Energy, Gwangju Institute of Science and Technology (GIST) , 123 Cheomdan-gwagiro, Buk-gu, Gwangju 61005, Republic of Korea
| | - Sung Yang
- School of Mechanical Engineering and ‡Research Institute of Solar and Sustainable Energy, Gwangju Institute of Science and Technology (GIST) , 123 Cheomdan-gwagiro, Buk-gu, Gwangju 61005, Republic of Korea
| | - Jongho Lee
- School of Mechanical Engineering and ‡Research Institute of Solar and Sustainable Energy, Gwangju Institute of Science and Technology (GIST) , 123 Cheomdan-gwagiro, Buk-gu, Gwangju 61005, Republic of Korea
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20
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Choi M, Jeong JJ, Kim SH, Kim SW. Reduction of Motion Artifacts and Improvement of R Peak Detecting Accuracy Using Adjacent Non-Intrusive ECG Sensors. SENSORS 2016; 16:s16050715. [PMID: 27196910 PMCID: PMC4883406 DOI: 10.3390/s16050715] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 05/05/2016] [Accepted: 05/11/2016] [Indexed: 11/16/2022]
Abstract
Non-intrusive electrocardiogram (ECG) monitoring has many advantages: easy to measure and apply in daily life. However, motion noise in the measured signal is the major problem of non-intrusive measurement. This paper proposes a method to reduce the noise and to detect the R peaks of ECG in a stable manner in a sitting arrangement using non-intrusive sensors. The method utilizes two capacitive ECG sensors (cECGs) to measure ECG, and another two cECGs located adjacent to the sensors for ECG are added to obtain the information on motion. Then, active noise cancellation technique and the motion information are used to reduce motion noise. To verify the proposed method, ECG was measured indoors and during driving, and the accuracy of the detected R peaks was compared. After applying the method, the sum of sensitivity and positive predictivity increased 8.39% on average and 26.26% maximally in the data. Based on the results, it was confirmed that the motion noise was reduced and that more reliable R peak positions could be obtained by the proposed method. The robustness of the new ECG measurement method will elicit benefits to various health care systems that require noninvasive heart rate or heart rate variability measurements.
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Affiliation(s)
- Minho Choi
- Department of Creative IT Engineering and Future IT Innovation Laboratory, Pohang University of Science and Technology (POSTECH), Pohang, Kyungbuk 790-784, Korea.
| | - Jae Jin Jeong
- Department of Electrical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Kyungbuk 790-784, Korea.
| | - Seung Hun Kim
- Department of Electrical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Kyungbuk 790-784, Korea.
| | - Sang Woo Kim
- Department of Electrical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Kyungbuk 790-784, Korea.
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Fong EM, Chung WY. A Hygroscopic Sensor Electrode for Fast Stabilized Non-Contact ECG Signal Acquisition. SENSORS 2015; 15:19237-50. [PMID: 26251913 PMCID: PMC4570369 DOI: 10.3390/s150819237] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2015] [Revised: 07/24/2015] [Accepted: 07/24/2015] [Indexed: 11/16/2022]
Abstract
A capacitive electrocardiography (cECG) technique using a non-invasive ECG measuring technology that does not require direct contact between the sensor and the skin has attracted much interest. The system encounters several challenges when the sensor electrode and subject’s skin are weakly coupled. Because there is no direct physical contact between the subject and any grounding point, there is no discharge path for the built-up electrostatic charge. Subsequently, the electrostatic charge build-up can temporarily contaminate the ECG signal from being clearly visible; a stabilization period (3–15 min) is required for the measurement of a clean, stable ECG signal at low humidity levels (below 55% relative humidity). Therefore, to obtain a clear ECG signal without noise and to reduce the ECG signal stabilization time to within 2 min in a dry ambient environment, we have developed a fabric electrode with embedded polymer (FEEP). The designed hygroscopic FEEP has an embedded superabsorbent polymer layer. The principle of FEEP as a conductive electrode is to provide humidity to the capacitive coupling to ensure strong coupling and to allow for the measurement of a stable, clear biomedical signal. The evaluation results show that hygroscopic FEEP is capable of rapidly measuring high-accuracy ECG signals with a higher SNR ratio.
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Affiliation(s)
- Ee-May Fong
- Department of Electronic Engineering, Pukyong National University, Busan 608-737, Korea.
| | - Wan-Young Chung
- Department of Electronic Engineering, Pukyong National University, Busan 608-737, Korea.
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Bruser C, Antink CH, Wartzek T, Walter M, Leonhardt S. Ambient and Unobtrusive Cardiorespiratory Monitoring Techniques. IEEE Rev Biomed Eng 2015; 8:30-43. [PMID: 25794396 DOI: 10.1109/rbme.2015.2414661] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Monitoring vital signs through unobtrusive means is a goal which has attracted a lot of attention in the past decade. This review provides a systematic and comprehensive review over the current state of the field of ambient and unobtrusive cardiorespiratory monitoring. To this end, nine different sensing modalities which have been in the focus of current research activities are covered: capacitive electrocardiography, seismo- and ballistocardiography, reflective photoplethysmography (PPG) and PPG imaging, thermography, methods relying on laser or radar for distance-based measurements, video motion analysis, as well as methods using high-frequency electromagnetic fields. Current trends in these subfields are reviewed. Moreover, we systematically analyze similarities and differences between these methods with respect to the physiological and physical effects they sense as well as the resulting implications. Finally, future research trends for the field as a whole are identified.
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Meziane N, Yang S, Shokoueinejad M, Webster JG, Attari M, Eren H. Simultaneous comparison of 1 gel with 4 dry electrode types for electrocardiography. Physiol Meas 2015; 36:513-29. [DOI: 10.1088/0967-3334/36/3/513] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Torfs T, Chen YH, Kim H, Yazicioglu RF. Noncontact ECG recording system with real time capacitance measurement for motion artifact reduction. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2014; 8:617-625. [PMID: 25314708 DOI: 10.1109/tbcas.2014.2359053] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A system for noncontact ECG recording is proposed that measures the real time electrode-body capacitance concurrently with the ECG as a reference signal for motion artifact reduction. Simultaneous recordings of these two signals from the human body in the presence of electrode motion artifacts are shown and an adaptive least-mean-squares (LMS) filtering algorithm run on these signals is demonstrated to be able to reduce the severity of certain types of electrode motion artifacts.
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25
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Serteyn A, Vullings R, Meftah M, Bergmans JWM. Motion artifacts in capacitive ECG measurements: reducing the combined effect of DC voltages and capacitance changes using an injection signal. IEEE Trans Biomed Eng 2014; 62:264-73. [PMID: 25137720 DOI: 10.1109/tbme.2014.2348178] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Capacitive electrodes are a promising alternative to the conventional adhesive electrodes for ECG measurements. They provide more comfort to the patient when integrated in everyday objects (e.g., beds or seats) for long-term monitoring. However, the application of capacitive sensors is limited by their high sensitivity to motion artifacts. For example, motion at the body-electrode interface causes variations of the coupling capacitance which, in the presence of a dc voltage across the coupling capacitor, create strong artifacts in the measurements. The origin, relevance, and reduction of this specific and important type of artifacts are studied here. An injection signal is exploited to track the variations of the coupling capacitance in real time. This information is then used by an identification scheme to estimate the artifacts and subtract them from the measurements. The method was evaluated in simulations, lab environments, and in a real-life recording on an adult's chest. For the type of artifact under study, a strong artifact reduction ranging from 40 dB for simulated data to 9 dB for a given real-life recording was achieved. The proposed method is automated, does not require any knowledge about the measurement system parameters, and provides an online estimate for the dc voltage across the coupling capacitor.
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26
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Capacitive measurement of ECG for ubiquitous healthcare. Ann Biomed Eng 2014; 42:2218-27. [PMID: 25052344 DOI: 10.1007/s10439-014-1069-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 07/11/2014] [Indexed: 10/25/2022]
Abstract
The technology for measuring ECG using capacitive electrodes and its applications are reviewed. Capacitive electrodes are built with a high-input-impedance preamplifier and a shield on their rear side. Guarding and driving ground are used to reduce noise. An analysis of the intrinsic noise shows that the thermal noise caused by the resistance in the preamplifier is the dominant factor of the intrinsic noise. A fully non-contact capacitive measurement has been developed using capacitive grounding and applied to a non-intrusive ECG measurement in daily life. Many ongoing studies are examining how to enhance the quality and ease of applying electrodes, thus extending their applications in ubiquitous healthcare from attached-on-object measurements to wearable or EEG measurements.
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Lee SM, Kim JH, Byeon HJ, Choi YY, Park KS, Lee SH. A capacitive, biocompatible and adhesive electrode for long-term and cap-free monitoring of EEG signals. J Neural Eng 2013; 10:036006. [PMID: 23574793 DOI: 10.1088/1741-2560/10/3/036006] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Long-term electroencephalogram (EEG) monitoring broadens EEG applications to various areas, but it requires cap-free recording of EEG signals. Our objective here is to develop a capacitive, small-sized, adhesive and biocompatible electrode for the cap-free and long-term EEG monitoring. APPROACH We have developed an electrode made of polydimethylsiloxane (PDMS) and adhesive PDMS for EEG monitoring. This electrode can be attached to a hairy scalp and be completely hidden by the hair. We tested its electrical and mechanical (adhesive) properties by measuring voltage gain to frequency and adhesive force using 30 repeat cycles of the attachment and detachment test. Electrode performance on EEG was evaluated by alpha rhythm detection and measuring steady state visually evoked potential and N100 auditory evoked potential. MAIN RESULTS We observed the successful recording of alpha rhythm and evoked signals to diverse stimuli with high signal quality. The biocompatibility of the electrode was verified and a survey found that the electrode was comfortable and convenient to wear. SIGNIFICANCE These results indicate that the proposed EEG electrode is suitable and convenient for long term EEG monitoring.
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Affiliation(s)
- Seung Min Lee
- Department of Biomedical Engineering, College of Health Science, Korea University, Seoul 136-100, Korea.
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Abstract
Noncontact, capacitive electrocardiogram (ECG) measurements are complicated by motion artifacts from the relative movement between the ECG electrodes and the subject. To compensate for such motion we propose to employ first and second order gradiometer electrode designs. A MATLAB-based simulation tool to enable assessment of different electrode configurations and placements on human subjects has been developed to guide the refinement of electrode designs. Experimental measurements of the sensitivity, motion artifact cancellation, and common mode rejection for various prototype designs were conducted with human subjects. Second order gradiometer electrode designs appear to give the best performance as measured by signal to noise plus distortion ratio. Finally, both gradiometer designs were compared with standard ECG recording methods and showed less than 1% beat detection mismatch employing an open source beat detection algorithm.
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Affiliation(s)
- GuoChen Peng
- Electrical and Computer Engineering Department, University of Rochester, Rochester, NY 14627-0231, USA.
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Czaplik M, Eilebrecht B, Walocha R, Walter M, Schauerte P, Leonhardt S, Rossaint R. The reliability and accuracy of a noncontact electrocardiograph system for screening purposes. Anesth Analg 2011; 114:322-7. [PMID: 22104072 DOI: 10.1213/ane.0b013e31823f4182] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
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.
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Affiliation(s)
- Michael Czaplik
- Department of Anesthesiology, University Hospital RWTH Aachen, Aachen, Germany.
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Wartzek T, Eilebrecht B, Lem J, Lindner HJ, Leonhardt S, Walter M. ECG on the road: robust and unobtrusive estimation of heart rate. IEEE Trans Biomed Eng 2011; 58:3112-20. [PMID: 21824839 DOI: 10.1109/tbme.2011.2163715] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Modern automobiles include an increasing number of assistance systems to increase the driver's safety. This feasibility study investigated unobtrusive capacitive ECG measurements in an automotive environment. Electrodes integrated into the driving seat allowed to measure a reliable ECG in 86% of the drivers; when only (light) cotton clothing was worn by the drivers, this value increased to 95%. Results show that an array of sensors is needed that can adapt to the different drivers and sitting positions. Measurements while driving show that traveling on the highway does not distort the signal any more than with the car engine turned OFF, whereas driving in city traffic results in a lowered detection rate due to the driver's heavier movements. To enable robust and reliable estimation of heart rate, an algorithm is presented (based on principal component analysis) to detect and discard time intervals with artifacts. This, then, allows a reliable estimation of heart rate of up to 61% in city traffic and up to 86% on the highway: as a percentage of the total driving period with at least four consecutive QRS complexes.
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Affiliation(s)
- Tobias Wartzek
- Chair of Medical Information Technology, RWTH Aachen University, Aachen, Germany.
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