A wirelessly-powered electro-acupuncture based on Adaptive Pulse Width Mono-Phase stimulation

A wirelessly-powered electro-acupuncture (EA) that dynamically adapts to body-impedance variation (BIV), is proposed. The proposed EA consists of a slender needle, a helical antenna (70 turns, 1mm diameter) using conductive yarn (100pm diameter, 6.6Ω2/m), and a 1.56mm² stimulator chip fabricated in 0.18μm 1P6M CMOS process. A stable supply voltage of 1V is wirelessly generated from 433MHz-ISM band with sensitivity of -16dBm. To deal with BIV in the range of 100KΩ-200kΩ, Adaptive-Pulse-Width (APW) scheme is introduced to maintain constant charge injection of 80nC per stimulation. A pair of EAs forms an EA node, and they operate in Alternate Mono-Phase (AMP) fashion to guarantee the safety by neutralization of the injected charge.