Fully biodegradable water-soluble triboelectric nanogenerator for human physiological monitoring

The biodegradable triboelectric nanogenerators (TENGs) for monitoring human physiological signals have attracted immensely attention in recent years. In this work, a water-soluble TENG (WS-TENG) is manufactured by using biodegradable recycled papers and water-soluble graphite electrode. The cellulose nanocrystal (CNC) in the papers is extracted and further mixed with methylcellulose (MC) to form a CNC/MC film, which can serve as the positive electrification material and form a TENG device with the common MC film as the negative electrification material. This low-cost, light weight and biodegradable WS-TENG that can be directly washed away by water is developed as a bandage sensor. Unlike traditional gauze sensors, the water-insoluble parts of our cellulose-based can be easily separated from water for reuse. The variation of the output voltage of WS-TENG between 0 V and 2 V can accurately distinguish various respiratory states, which is enough to be used as a real-time physiological signal monitoring sensor. This fully water-soluble device can serve as an advanced medical sensor and expand the application of TENG in health care monitoring field.