Feet-Beat: A Wearable device using FITS

Abstract—The Human feet have long been thought to be closely related to overall body health, from which a wealth of cardiovascular and skeleto-muscular data can be gleaned. With the help of this study, Feet-Beat is the first wearable foot-based device capable of detecting both pedal pulses and muscular activity. A five-unit sensing array has been built and characterized using the flexible iontronic sensing (FITS) technology in order to monitor both pedal pulse signals and muscle actions. It is built into the tongue of a running shoe to capture signals instantly. The linear array also enables alignment-free pulse signal collection and offers a spatial reference for muscular activity. For individual units, an ultrahigh sensitivity of up to 1 nF/mmHg has been attained with a range of 1 to 200 mmHg. The heart rate (HR) and respiratory rate (RR) from the pedal pulse waveforms have been determined, and the pulse-derived HR is compared with the electrocardiogram (ECG). Additionally, distinct pedal movements have been analyzed using individual tendon responses, from which multichannel signals can be used to separate various activities.  Index Terms—Muscular activity, Sensing array, Flexible ion- tronic sensing (FITS), Pulse signal collection