Photonic Sensing of Electrophysiological Activity for Wearable Applications

Photonic biosensors, featuring small size, lightweight, and remote sensing ability through optical fibers, show huge potential for wearable bioelectric applications. Electro-optic (EO) devices have high-input impedance and can achieve small-driving voltages, just what is required for a sensor targeting bioelectric activity monitoring. This paper proposes a multi-parameter bioelectric acquisition platform with a photonic sensor based on EO methods, and electronic circuitry for signal conditioning, filtering and amplification. The core sensing technology is based on a Lithium Niobate Mach-Zehnder interferometer modulator, which responds to the bioelectric signal by modulating the input light intensity. The photonic sensor performance was compared with standard acquisition systems. Results have shown that the developed sensor is reliable and allows multi-parameter acquisition with acceptable gain (from 1 to 4 mV/μV), sensitivity (minimum detected field of 20 μV), frequency content, and clinical relevance.