Soft Wearable Sensors for Precise Physiological Signals Measurements Based on the Fabric-Substrate Complementary Split-Ring Resonator

This paper presents novel fabric substrate and manufacturing technique for microwave sensors. Fabric-substrate complementary split-ring resonator (FSCSRR) sensors can be applied to wearable devices for vital sign measurement. By attaching the microwave sensor, a soft wearable sensor based on FSCSRR in clothes can be realized. The respiratory and heartbeat signals can be high sensitively extracted by the frequency and amplitude deviations of FSCSRR where the sensor is placed inside a clothes, facing to the chest. The property of the fabric substrate is measured, and the impacts of the low-conductivity on sensitivity of the sensor is analyzed. Although the quality factor of sensor decreases, the proposed FSCSRR sensor is verified sufficiently sensitive while measuring of cardiorespiratory signals, and the errors of the heartbeat rate is less than 0.39%.