Zero-waste emission design of sustainable and programmable actuators

Moisture-responsive actuators are widely used as energy-harvesting devices due to their excellent ability to spontaneously and continuously convert external energy into kinetic energy. However, it remains a challenge to sustainably synthesize moisture-driven actuators. Here, we present a sustainable zero-waste emission methodology to prepare soft actuators using carbon nano-powders and biodegradable polymers through a water evaporation method. Due to the water solubility and recyclability of the matrixes employed here, the entire synthetic process achieves zero-waste emission. Our composite films featured strong figures of merit and capabilities with a 250 degrees maximum bending angle under 90% relative humidity. Programmable motions and intelligent bionic applications, including walkers, smart switches, robotic arms, flexible excavators, and hand-shaped actuators, were further achieved by modulating the geometry of the actuators. This sustainable method for actuators' fabrication has great potential in large-scale productions and applications due to its advantages of zero-waste emission manufacturing, excellent recyclability, inherent adaptive integration, and low cost.