May 25, 2021SensorsOpen Access

Novel Stable Capacitive Electrocardiogram Measurement System

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Why the study?

A noncontact electrocardiogram measurement system was developed to replace conventional electrode pads during measurement.

Does a novel noncontact capacitive ECG measurement system provide stable and accurate ECG signals compared to conventional contact ECG systems?

Structured PICO

Does a novel noncontact capacitive ECG measurement system provide stable and accurate ECG signals compared to conventional contact ECG systems?

Population

Simulated environments with environmental and motion artifact interference

Intervention

Proposed noncontact ECG measurement system based on capacitive sensing (comprising surface guard ring, optimal input resistance, ground guard ring, optimal voltage divider feedback, and capacitive driven right leg circuit)

Comparator

Conventional contact ECG systems and standard capacitive ECG electrodes

Outcome

Stability of measured ECG signals and similarity of R-R intervalssurrogate

A novel noncontact capacitive ECG measurement system demonstrates high similarity (98.6%) to conventional contact ECGs, suggesting potential for everyday use.

Implication

Noncontact ECG may improve comfort and reduce noise; leaves open prospective clinical validation before adoption.

Abstract

This study presents a noncontact electrocardiogram (ECG) measurement system to replace conventional ECG electrode pads during ECG measurement. The proposed noncontact electrode design comprises a surface guard ring, the optimal input resistance, a ground guard ring, and an optimal voltage divider feedback. The surface and ground guard rings are used to reduce environmental noise. The optimal input resistor mitigates distortion caused by the input bias current, and the optimal voltage divider feedback increases the gain. Simulated gain analysis was subsequently performed to determine the most suitable parameters for the design, and the system was combined with a capacitive driven right leg circuit to reduce common-mode interference. The present study simulated actual environments in which interference is present in capacitive ECG signal measurement. Both in the case of environmental interference and motion artifact interference, relative to capacitive ECG electrodes, the proposed electrodes measured ECG signals with greater stability. In terms of R-R intervals, the measured ECG signals exhibited a 98.6% similarity to ECGs measured using contact ECG systems. The proposed noncontact ECG measurement system based on capacitive sensing is applicable for use in everyday life.