Wearable wireless biopotential electrode for ECG monitoring

Abstract

A single channel wearable wireless ECG biopotential electrode is presented. The device is built up of commercial components and utilizes 434 MHz license free frequency band. The three electrode, two-stage biopotential amplifier design and the wireless signal transfer system, yielded very low noise and excellent interference rejection. A CMRR of 100 dB at 50 Hz and an equivalent input voltage noise of 0.4 μVrms were measured during the tests of the developed prototype. The amplified analog ECG signal is sampled with 500 Hz by a 10 bit Analog-to-Digital Converter (ADC) and transmitted via UHF Amplitude-Shift Keying transmitter to a dedicated receiver module USB connected to a PC. Both the ADC and RF-transmitter are embedded in the flash-based 8-bit CMOS Microcontroller rfPIC12F676F. The receiver module is based on the low cost single conversion superheterodyne receiver rfRXD0420, interfaced with an 8-bit CMOS microcontroller PIC16C745 with USB support. The developed electrode is powered by a small coin cell lithium battery and can perform continuous ECG recording and transmission for more than a week.