Non-Contact Measurements of Electrocardiogram and Cough-Associated Electromyogram from the Neck Using In-Pillow Common Cloth Electrodes: A Proof-of-Concept Study

Abstract

Asthma and chronic obstructive pulmonary disease are associated with nocturnal cough and changes in heart rate. In this work, the authors propose a proof-of-concept non-contact system for performing capacitive electrocardiogram (cECG) and cough-associated capacitive electromyogram (cEMG) measurements using cloth electrodes under a pillowcase. Two electrodes were located along with the approximate vector of lead II ECG and were used for both cECG and cEMG measurements. A signature voltage follower was introduced after each electrode to detect biopotentials with amplitudes of approximately 100 µV. A bootstrapping technique and nonlinear electrical component were combined and implemented in the voltage follower to attain a high input impedance and rapid static discharge. The measurement system was evaluated in a laboratory experiment for seven adult males and one female (average age: 22.5 ± 1.3 yr). The accuracy of R-wave detection for 2-min resting periods was 100% in six subjects, with an overall average of 87.5% ± 30.0%. Clearly visible cEMGs were obtained for each cough motion for all subjects, synchronized with reference EMGs from submental muscle. Although there remains room for improvement in practical use, the proposed system is promising for unobtrusive detection of heart rate and cough over a prolonged period of time.

Emerging sensing and modeling technologies for wearable and cuffless blood pressure monitoring

“…3 ) are attached to the skin of the arms, legs, and chest. Three types of ECG electrodes are used, namely wet 37 – 39 , dry, and capacitively coupled electrodes 40 . Wet and dry electrodes are directly connected to the skin and can measure skin impedance via conductive material.…”

“… a Schematic diagram of in-pillow capacitive cloth electrodes 40 . b Schematic diagrams of the standard Ag/AgCl electrode and prepared electrode 78 .…”

“…Noise reduction is an indispensable component for wearable cuffless BP monitoring systems. The most broadly used denoising tool is filter, which has been typically applied to suppress the noise of a certain frequency range in TAG 75 , ECG 40 , 78 , 79 , IPG 7 , 44 , 49 , PPG 13 , 75 , ultrasound 76 , 80 , and BCG 72 , 81 signals. While filtering can serve as a universal tool for almost all types of sensing modalities, there have also been signal-specific denoise methods developed to improve the noise removal efficiency and accuracy.…”