Bandage based energy generators activated by sweat in wireless skin electronics for continuous physiological monitoring

In the past decades, wearable electronics have attracted extensive attention for their excellent electrical performance and superior mechanical characteristics in various applications, including human machine interfaces, clinical treatment, and healthcare monitoring. Powering technology as the indispensable component for intelligent wearable electronics, have raised much concern for bulky size, low energy capacity, and rigid format. Here, we have developed an ultrathin, flexible, conformable sweat activated battery with the high power density (16.3 mW/cm2) and impressive energy capacity (74.4 mAh). Due to the advanced biocompatible materials, the battery is capable of mounting onto human skin for long-term application without any irritation risk. After optimizing the electrical characteristics, the battery@ 0.3 mm Mg layer can yield the high open-circuit voltage and short-circuit current of 1.41 V and 53.4 mA for a long time (over 3.5 hrs). Besides, the battery can stabilize its electrical performance under various mechanical deformations, such as bending, twisting at different angles, which shall lead to the practical applications as mounted onto human body. The high-performance sweat-activated batteries@ 0.1 mm Mg layer enable powering electronic devices for a long-term duration, for instance, continuously lighting 120 LEDs for over 4 hrs, and also offer enough power to support Bluetooth wireless operation for recording of physiological signals for over 1.2 hrs, allowing real-time monitoring of exercising intensity level, skin temperature, pulse rate, and oxygen saturation in blood.