Biomimetic array actuators for multisituation low-grade energy harvesting

Low-grade energy resources are abundant and widely available, yet efficiently harnessing and continuously collecting this energy presents a considerable challenge, leading to significant energy losses. In this work, we introduce a biomimetic array actuator constructed with a sodium alginate (SA)-tellurium nanowires (Te NWs)/polyvinylidene fluoride (PVDF) bilayer structure that responds to various stimuli such as low temperature, natural light, and humidity. Significantly, this actuator generates autonomous self-oscillatory motion driven by an internal mechanical feedback loop. Utilizing its high-frequency self-oscillating motion, this actuator efficiently harnesses low-grade energy sources, including waste heat, non-concentrated sunlight, and exhaust steam. Under various driving conditions, including a 60 °C heater, natural light, and 70 °C steam, the 3 × 3 array actuators can generate peak voltages of 1.5 V, 2 V, and 4 V, respectively. This research has the potential to unlock opportunities for a range of low-grade energy harvesting technologies utilizing flexible actuators.