Unblended polydimethylsiloxane dielectrics for non-contact electrocardiograph bioelectrodes

Dielectric materials play crucial roles in the non-contact recording of electrocardiograms (ECGs), allowing cardiac physiological signals to be monitored and abnormalities detected early. Previous dielectrics are rigid, unstable, require expensive fabrication, and induce severe noise. PDMS is a poly...

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Main Author:	Haruna, Umar Alhassan
Format:	Thesis
Language:	English
Published:	2023
Subjects:	TK Electrical engineering Electronics Nuclear engineering
Online Access:	http://eprints.utm.my/102819/1/UmarAlhassanHarunaPSKE2023.pdf.pdf
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spelling	my-utm-ep.1028192023-09-24T03:17:11Z Unblended polydimethylsiloxane dielectrics for non-contact electrocardiograph bioelectrodes 2023 Haruna, Umar Alhassan TK Electrical engineering. Electronics Nuclear engineering Dielectric materials play crucial roles in the non-contact recording of electrocardiograms (ECGs), allowing cardiac physiological signals to be monitored and abnormalities detected early. Previous dielectrics are rigid, unstable, require expensive fabrication, and induce severe noise. PDMS is a polymer with remarkable biomedical properties suitable for non-contact bioelectrodes. However, the poor dielectric capability of PDMS has led to costly attempts to improve it. This research introduces an affordable technique to explore and characterize unblended PDMS films as dielectrics for non-contact ECG bioelectrodes by varying the weight mix ratio of Sylgard 184 TM silicone elastomer and its crosslinker. Capacitance and relative permittivity were measured and estimated using the parallel-plate technique in the frequency range of the LCR meter. Skin impedance values were also measured for different skin conditions using the Hioki impedance analyzer test frequency of 4 Hz - 1 MHz. Non-contact ECG measurements are affected by morphology of the dielectric, bioelectrode conductor, contact area, and skin conditions. To investigate the impact of these factors on skin impedance, the skin bioelectrode interface was modeled using equivalent circuits for wet, direct contact, and non-contact modes and analyzed using least-squares non-linear curve fit. Finally, the proposed approach was verified by recording ECG using different bioelectrodes and dielectrics. Due to susceptibility to motion artifacts and electrical interferences, digital filters were introduced to improve the quality of ECG recorded. The results demonstrate the effectiveness of the proposed method for improving the dielectric performance of unblended PDMS films, with a steady increase in capacitance (50.53 pF to 102.86 pF) and relative permittivity (0.19 to 0.69) observed with an increase in the proportion of the crosslinker. Good agreement was found between the measured skin impedance and equivalent circuit models, but differences exist in estimated circuit parameters. The unblended PDMS films with the highest mix ratio (10:2) successfully recorded visible P-QRS-T peaks in ECG. Skin conditions, bioelectrode conductivity, dielectric thickness and porosity, and the OpenBCI board filtering parameters affect the ECG recordings. This study confirms the potential of unblended PDMS films for non-contact bioelectrodes to detect heart abnormalities early. 2023 Thesis http://eprints.utm.my/102819/ http://eprints.utm.my/102819/1/UmarAlhassanHarunaPSKE2023.pdf.pdf application/pdf en public http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:152216 phd doctoral Universiti Teknologi Malaysia Faculty of Engineering - School of Electrical Engineering
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	TK Electrical engineering Electronics Nuclear engineering
spellingShingle	TK Electrical engineering Electronics Nuclear engineering Haruna, Umar Alhassan Unblended polydimethylsiloxane dielectrics for non-contact electrocardiograph bioelectrodes
description	Dielectric materials play crucial roles in the non-contact recording of electrocardiograms (ECGs), allowing cardiac physiological signals to be monitored and abnormalities detected early. Previous dielectrics are rigid, unstable, require expensive fabrication, and induce severe noise. PDMS is a polymer with remarkable biomedical properties suitable for non-contact bioelectrodes. However, the poor dielectric capability of PDMS has led to costly attempts to improve it. This research introduces an affordable technique to explore and characterize unblended PDMS films as dielectrics for non-contact ECG bioelectrodes by varying the weight mix ratio of Sylgard 184 TM silicone elastomer and its crosslinker. Capacitance and relative permittivity were measured and estimated using the parallel-plate technique in the frequency range of the LCR meter. Skin impedance values were also measured for different skin conditions using the Hioki impedance analyzer test frequency of 4 Hz - 1 MHz. Non-contact ECG measurements are affected by morphology of the dielectric, bioelectrode conductor, contact area, and skin conditions. To investigate the impact of these factors on skin impedance, the skin bioelectrode interface was modeled using equivalent circuits for wet, direct contact, and non-contact modes and analyzed using least-squares non-linear curve fit. Finally, the proposed approach was verified by recording ECG using different bioelectrodes and dielectrics. Due to susceptibility to motion artifacts and electrical interferences, digital filters were introduced to improve the quality of ECG recorded. The results demonstrate the effectiveness of the proposed method for improving the dielectric performance of unblended PDMS films, with a steady increase in capacitance (50.53 pF to 102.86 pF) and relative permittivity (0.19 to 0.69) observed with an increase in the proportion of the crosslinker. Good agreement was found between the measured skin impedance and equivalent circuit models, but differences exist in estimated circuit parameters. The unblended PDMS films with the highest mix ratio (10:2) successfully recorded visible P-QRS-T peaks in ECG. Skin conditions, bioelectrode conductivity, dielectric thickness and porosity, and the OpenBCI board filtering parameters affect the ECG recordings. This study confirms the potential of unblended PDMS films for non-contact bioelectrodes to detect heart abnormalities early.
format	Thesis
qualification_name	Doctor of Philosophy (PhD.)
qualification_level	Doctorate
author	Haruna, Umar Alhassan
author_facet	Haruna, Umar Alhassan
author_sort	Haruna, Umar Alhassan
title	Unblended polydimethylsiloxane dielectrics for non-contact electrocardiograph bioelectrodes
title_short	Unblended polydimethylsiloxane dielectrics for non-contact electrocardiograph bioelectrodes
title_full	Unblended polydimethylsiloxane dielectrics for non-contact electrocardiograph bioelectrodes
title_fullStr	Unblended polydimethylsiloxane dielectrics for non-contact electrocardiograph bioelectrodes
title_full_unstemmed	Unblended polydimethylsiloxane dielectrics for non-contact electrocardiograph bioelectrodes
title_sort	unblended polydimethylsiloxane dielectrics for non-contact electrocardiograph bioelectrodes
granting_institution	Universiti Teknologi Malaysia
granting_department	Faculty of Engineering - School of Electrical Engineering
publishDate	2023
url	http://eprints.utm.my/102819/1/UmarAlhassanHarunaPSKE2023.pdf.pdf
_version_	1783729221611290624

Unblended polydimethylsiloxane dielectrics for non-contact electrocardiograph bioelectrodes

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