A Wearable Smart Ring for Measuring Bioimpedance in the Palmar Digital Arteries

Bioimpedance (BioZ) is a non-invasive and low-cost technology capable of monitoring conductivity rapidly. BioZ holds promise for integration into wearable devices for outpatient monitoring. Here, we propose the integration of BioZ into a smart ring form factor using electrodes coated with poly(3,4-ethylenedioxythiophene) (PEDOT) conductive polymer. PEDOT reduces contact electrode impedance by increasing the effective contact area at the skin-electrode interface and having high ionic conductivity. In this feasibility study, we developed a ring sensor, deposited PEDOT on the electrodes, and compared its capability to record pulsatile BioZ data at the finger against untreated electrodes. We performed electrochemical impedance spectroscopy (EIS) and BioZ measurements. EIS results showed that electrode contact impedance decreased by a factor of 1.2 compared to the untreated electrodes at the relevant frequency. Our results show the capability of our smart ring sensor to detect pulsatile BioZ at the digital arteries.