Polystyrene-Based Triboelectric Nanogenerators for Self-Powered Multifunctional Human Activity Monitoring

Polystyrene (PS)-based triboelectric nanogenerators (PS-TENGs) with PS as the primary friction layer have been reported. PS-TENGs were developed by a simple drop-cast method and arranged in vertical contact-separation mode with aluminum as the other triboelectric layer. The PS-TENG (area: ∼15 cm2) prepared with 40 mg/mL PS solution generated an open-circuit voltage of ∼140 V, short-circuit current of ∼6 μA, and instantaneous power of ∼120 μW (power density of ∼80 mW/m2) when subjected to a force of ∼12 N. The PS-TENG also powered 120 green light-emitting diodes and low-power electronic systems like a calculator and digital clock. The PS-TENG was further explored as a self-powered human motion monitoring device where it effectively detected trivial human motions like hand tapping, walking, running, jumping, and various joint movements. In addition, small-scale motions like that of fingers and coughing impulses and throat-clearing vibrations in the throat, nasal breath, and mouth air blows were also precisely captured by the PS-TENG. These results signified huge capabilities of PS as a triboelectric material, which remains widely unexplored despite its suitable position in the triboelectric series.