Towards a Miniaturized, Low Power, Batteryless, and Wireless Bio-Potential Sensing Node

This paper presents a miniaturized (7.5mm radius), low power (8.8µW) sensing device capable of recording bio-potentials in applications utilizing electrocardiogram (ECG), electromyography (EMG), and electrooculogram (EOG) while operating as a battery-less and wireless device. The sensing node utilizes wireless power transfer (WPT) in the ISM band of 40.68MHz enabling battery less operation and a wireless data uplink is performed in the ISM band utilizing short pulses of 915MHz. The sensing IC (integrated circuit) consists of a rectifier, power management unit, clock recovery unit, amplifier, ADC (analog-to-digital converter) and a transmitter. The IC is integrated into the sensing node through a specially designed miniaturized loop antenna for WPT and a co-designed dipole antenna for the uplink transmit. The sensing node is fabricated in the 180nm complementary metal oxide semiconductor (CMOS) process and is successfully verified for recording bio-potential signals like ECG, EMG and EOG.