A flexible transparent one-structure tribo-piezo-pyroelectric hybrid energy generator based on bio-inspired silver nanowires network for biomechanical energy harvesting and physiological monitoring

The rapid development of wearable electronics like e-skins calls for self-powered sensing to harvest diverse bio-energies from human body as well as detect human physiological signals. Here, we report a novel, flexible and biocompatible triboelectric-piezoelectric-pyroelectric hybrid nanogenerator based on a significantly simplified structure with good transparency which mainly due to high-performance transparent electrodes (TEs). Inspired by gradually optimized leaf venation (LV), silver nanowires were arranged into a LV-like network through a green and cost-effective approach. The unique structure led to an ultra-high transmission up to 99% (at 68.2 Ω sq−1 sheet resistance) and sheet resistances as low as 1.4 Ω sq−1 (with 82% transmission). With 3 effects coupled, the generator can scavenge a maximum open-circuit output voltage of 55 V and 86 V to produce mechanical energy and thermal energy, respectively. In addition, the transparent hybrid nanogenerator can be conformally attached on different parts of body for real-time monitoring of various human vital signs including breath, heartbeat pulse and swallowing. With high transparency, the hybrid nanogenerator can be integrated with a thin liquid crystal film possessing thermochromic properties, potentially as a visualized thermometer for medical diagnostics. The research is a substantial advancement toward the realization of cost-effective self-powered sensing like pressure and temperature and its potential applications in device dimension miniaturization, healthcare monitoring, energy conversation, and wearable electronics.