Harmonic Error Cancellation for Accurate Square-wave-based Bio-Impedance Measurements

Saqib Subhan, Sohmyung Ha

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Bio-impedance spectroscopy, which measures impedance of the tissue over a frequency range, has been widely used to provide crucial information for monitoring human health. Its conventional methods using sine wave current stimulation of the tissue and sine wave demodulation of the resultant voltage provide an accurate impedance measurement, but involve bulky components and power inefficiency due to sinusoidal waveform generation and analog signal multiplication. Instead, the method using square wave clocks can be much more area and power efficient, but inherently has substantial errors in the measured result due to the presence of harmonics in square waves. In this paper we propose a technique to cancel the errors caused by harmonics of the square wave stimulation and demodulation. The technique, based on the fact that the magnitude ratio of all the harmonics of a square wave are known, cancels out harmonic errors by subtracting or adding the square-wave-based measured results at higher harmonics to the fundamental output as a simple post-processing calculation. Simulation results using a generic electrode and tissue model show that this technique can provide a precise measurement of the bio-impedance with <0.5% magnitude error and < 0.2 phase error considering just five frequency multiples. Because this method does not involve sinusoidal signal generation and analog mixing, it is adequate to be integrated in a wearable health monitoring device at low area and power overhead.

Original languageEnglish (US)
Title of host publication40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2018
PublisherInstitute of Electrical and Electronics Engineers Inc.
Pages4273-4276
Number of pages4
Volume2018-July
ISBN (Electronic)9781538636466
DOIs
StatePublished - Oct 26 2018
Event40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2018 - Honolulu, United States
Duration: Jul 18 2018Jul 21 2018

Other

Other40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2018
CountryUnited States
CityHonolulu
Period7/18/187/21/18

Fingerprint

Electric Impedance
Dielectric Spectroscopy
Health
Tissue
Demodulation
Electrodes
Equipment and Supplies
Monitoring
Clocks
Spectroscopy
Electric potential
Processing

Keywords

  • Bio-impedance spectroscopy
  • Error cancellation
  • square wave stimulation

ASJC Scopus subject areas

  • Signal Processing
  • Biomedical Engineering
  • Computer Vision and Pattern Recognition
  • Health Informatics

Cite this

Subhan, S., & Ha, S. (2018). Harmonic Error Cancellation for Accurate Square-wave-based Bio-Impedance Measurements. In 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2018 (Vol. 2018-July, pp. 4273-4276). [8513359] Institute of Electrical and Electronics Engineers Inc.. https://doi.org/10.1109/EMBC.2018.8513359

Harmonic Error Cancellation for Accurate Square-wave-based Bio-Impedance Measurements. / Subhan, Saqib; Ha, Sohmyung.

40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2018. Vol. 2018-July Institute of Electrical and Electronics Engineers Inc., 2018. p. 4273-4276 8513359.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Subhan, S & Ha, S 2018, Harmonic Error Cancellation for Accurate Square-wave-based Bio-Impedance Measurements. in 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2018. vol. 2018-July, 8513359, Institute of Electrical and Electronics Engineers Inc., pp. 4273-4276, 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2018, Honolulu, United States, 7/18/18. https://doi.org/10.1109/EMBC.2018.8513359
Subhan S, Ha S. Harmonic Error Cancellation for Accurate Square-wave-based Bio-Impedance Measurements. In 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2018. Vol. 2018-July. Institute of Electrical and Electronics Engineers Inc. 2018. p. 4273-4276. 8513359 https://doi.org/10.1109/EMBC.2018.8513359
Subhan, Saqib ; Ha, Sohmyung. / Harmonic Error Cancellation for Accurate Square-wave-based Bio-Impedance Measurements. 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2018. Vol. 2018-July Institute of Electrical and Electronics Engineers Inc., 2018. pp. 4273-4276
@inproceedings{cf6c421f9e0d4876a74ddeaf8791f7b2,
title = "Harmonic Error Cancellation for Accurate Square-wave-based Bio-Impedance Measurements",
abstract = "Bio-impedance spectroscopy, which measures impedance of the tissue over a frequency range, has been widely used to provide crucial information for monitoring human health. Its conventional methods using sine wave current stimulation of the tissue and sine wave demodulation of the resultant voltage provide an accurate impedance measurement, but involve bulky components and power inefficiency due to sinusoidal waveform generation and analog signal multiplication. Instead, the method using square wave clocks can be much more area and power efficient, but inherently has substantial errors in the measured result due to the presence of harmonics in square waves. In this paper we propose a technique to cancel the errors caused by harmonics of the square wave stimulation and demodulation. The technique, based on the fact that the magnitude ratio of all the harmonics of a square wave are known, cancels out harmonic errors by subtracting or adding the square-wave-based measured results at higher harmonics to the fundamental output as a simple post-processing calculation. Simulation results using a generic electrode and tissue model show that this technique can provide a precise measurement of the bio-impedance with <0.5{\%} magnitude error and < 0.2 phase error considering just five frequency multiples. Because this method does not involve sinusoidal signal generation and analog mixing, it is adequate to be integrated in a wearable health monitoring device at low area and power overhead.",
keywords = "Bio-impedance spectroscopy, Error cancellation, square wave stimulation",
author = "Saqib Subhan and Sohmyung Ha",
year = "2018",
month = "10",
day = "26",
doi = "10.1109/EMBC.2018.8513359",
language = "English (US)",
volume = "2018-July",
pages = "4273--4276",
booktitle = "40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2018",
publisher = "Institute of Electrical and Electronics Engineers Inc.",

}

TY - GEN

T1 - Harmonic Error Cancellation for Accurate Square-wave-based Bio-Impedance Measurements

AU - Subhan, Saqib

AU - Ha, Sohmyung

PY - 2018/10/26

Y1 - 2018/10/26

N2 - Bio-impedance spectroscopy, which measures impedance of the tissue over a frequency range, has been widely used to provide crucial information for monitoring human health. Its conventional methods using sine wave current stimulation of the tissue and sine wave demodulation of the resultant voltage provide an accurate impedance measurement, but involve bulky components and power inefficiency due to sinusoidal waveform generation and analog signal multiplication. Instead, the method using square wave clocks can be much more area and power efficient, but inherently has substantial errors in the measured result due to the presence of harmonics in square waves. In this paper we propose a technique to cancel the errors caused by harmonics of the square wave stimulation and demodulation. The technique, based on the fact that the magnitude ratio of all the harmonics of a square wave are known, cancels out harmonic errors by subtracting or adding the square-wave-based measured results at higher harmonics to the fundamental output as a simple post-processing calculation. Simulation results using a generic electrode and tissue model show that this technique can provide a precise measurement of the bio-impedance with <0.5% magnitude error and < 0.2 phase error considering just five frequency multiples. Because this method does not involve sinusoidal signal generation and analog mixing, it is adequate to be integrated in a wearable health monitoring device at low area and power overhead.

AB - Bio-impedance spectroscopy, which measures impedance of the tissue over a frequency range, has been widely used to provide crucial information for monitoring human health. Its conventional methods using sine wave current stimulation of the tissue and sine wave demodulation of the resultant voltage provide an accurate impedance measurement, but involve bulky components and power inefficiency due to sinusoidal waveform generation and analog signal multiplication. Instead, the method using square wave clocks can be much more area and power efficient, but inherently has substantial errors in the measured result due to the presence of harmonics in square waves. In this paper we propose a technique to cancel the errors caused by harmonics of the square wave stimulation and demodulation. The technique, based on the fact that the magnitude ratio of all the harmonics of a square wave are known, cancels out harmonic errors by subtracting or adding the square-wave-based measured results at higher harmonics to the fundamental output as a simple post-processing calculation. Simulation results using a generic electrode and tissue model show that this technique can provide a precise measurement of the bio-impedance with <0.5% magnitude error and < 0.2 phase error considering just five frequency multiples. Because this method does not involve sinusoidal signal generation and analog mixing, it is adequate to be integrated in a wearable health monitoring device at low area and power overhead.

KW - Bio-impedance spectroscopy

KW - Error cancellation

KW - square wave stimulation

UR - http://www.scopus.com/inward/record.url?scp=85056634733&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85056634733&partnerID=8YFLogxK

U2 - 10.1109/EMBC.2018.8513359

DO - 10.1109/EMBC.2018.8513359

M3 - Conference contribution

C2 - 30441298

AN - SCOPUS:85056634733

VL - 2018-July

SP - 4273

EP - 4276

BT - 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2018

PB - Institute of Electrical and Electronics Engineers Inc.

ER -