Biocompatible Poly(lactic acid)-Based Hybrid Piezoelectric and Electret Nanogenerator for Electronic Skin Applications

Human machine interface (HMI) devices, which can convert human motions to electrical signals to control/charge electronic devices, have attracted tremendous attention from the engineering and science fields. Herein, the high output voltage from a nonpiezoelectric meso-poly(lactic acid) (meso-PLA) electret-based triboelectric nanogenerator (NG) is combined with the relatively high current from a double-layered poly(l-lactic acid) (PLLA)-based piezoelectric nanogenerator (PENG) for an E-skin (electronic skin) (HMI) device application. The hybrid NG with a cantilever structure can generate an output voltage of 70 V and a current of 25 mu A at the resonance frequency of 19.7 Hz and a tip load of 4.71 g. Moreover, the output power of the hybrid NG reaches 0.31 mW, which is 11% higher than that from the PLLA-based PENG. Furthermore, it is demonstrated that the PLA-based hybrid NG can be used to turn a light-emitting diode light on and off through an energy management circuit during a bending test. Finally, it is demonstrated that the PLA-based woven E-skin device can generate the output signals of 35 V (V-oc) and 1 mu A (I-sc) during an elbow bending test. The advantages of biocompatible, ease of fabrication, and relatively high output power in the hybrid NG device show great promise for future E-skin applications.