Wireless passive fabric sensor for multi-ion detection in human sweat

Bodily fluids harbor critical biomarkers that are closely associated with human health. Analyzing their constituents provides valuable health-related insights, serving as a pivotal way for early diagnosis and health assessment. However, traditional wearable biochemical sensing solutions based on digital circuits face issues such as complex manufacturing processes, poor wearing comfort, and difficulties in long-term power supply, thereby limiting their utility in home care and chronic disease monitoring. This work designs a multi-channel, battery-free and wearable fabric biochemical sensor. Activated within magnetic field environment, the sensing fabric transduces biochemical information into electric signals that modulate the resonant circuit parameters, finally shifting the resonant frequency of the circuit. The multiple-ion sensing performance of fabric biochemical sensor was validated through sweat monitoring during physical exercise. The proposed fabric sensor has excellent sensitivity, reliability and minimal cross-channel coupling, offering a promising solution for real-time and routine monitoring of body fluids.