A Passive, Skin-Attachable Multi-Sensing Patch Based on Semi-Liquid Alloy Ni-GaIn for Wireless Epidermal Signal Monitoring and Body Motion Capturing

Wearable integrated systems that rely on liquid metal commonly require an extremely complicated, high-cost fabrication process, while lacking multiple sensing functions without conductive wires connected to external electronic systems. A multi-sensing wearable patch independent from sophisticated manufacturing method and excessive use of wires has yet to be developed. Herein, we introduce a wireless, battery-free, and skin-attachable patch with multiple sensing capacities, utilizing a low-budget, less time-consuming and design-customizable fabrication method. In an effort to achieve our goal, the general sensing system architecture is promoted, which consists of a semi-liquid alloy Ni-GaIn based strain sensor and a co-designed near-field-communication (NFC) tag integrating thermistor, photoresistor, as well as sensor interface circuits, enabling energy-autonomous power supply and wireless data transmission. In human volunteers, the patch was mounted on the skin surface to demonstrate real-time temperature and light intensity signal monitoring. Further evaluation of body motion capturing involved finger bending and swallowing, demonstrating the feasibility of practical applications in different scenarios. Continuous and simultaneous multi-type signal sensing using the wearable patch should enrich the dimensions of measurements of body response to daily activities, unveiling the potential for remote human health monitoring, advanced human–machine interfaces, and other applications of interest.