A Sock-Embedded Wireless Sensing System Employing Paper-Substrate-Based MEMS Tactile Sensors Array and Low-Power ASIC for Accurate and Comfortable AFib Monitoring

This article presents the design, system integration, and evaluation results of a sock-embedded, low-cost, comfortable, and easy-to-use wearable sensing system for atrial fibrillation (AFib) monitoring. A five-channel tactile sensors array is fabricated employing a paper substrate and spray-deposited metallization. A low-power application-specific integrated circuit (ASIC) is designed and fabricated to interface the sensors array. The sensors array, ASIC, and a Bluetooth low energy (BLE) chip are further integrated into a miniature wireless sensing system, which can be placed on the top of a foot inside of a sock in a comfortable manner. Evaluation of the sensing system under different sitting conditions is conducted with an electrocardiographic (ECG) sensor and a photoplethysmographic (PPG) sensor serving as sensing references, which demonstrates that the prototype system is capable of accurately measuring instant heart rate (HR) and heart rate variability (HRV) to detect AFib under typical sitting conditions with typical foot movements. Measurement results further indicate that supraventricular tachycardia (SVT) can also be detected.