Smart Materials & Structures

Biography

Biography: Lidong Zhang

Abstract

Humidity-driven motion is a fundamental process of energy conversion that is Essential for applications which require contact less actuation in response to the day-night rhythm of atmospheric humidity. In this work we demonstrate that mechanical bistability caused by rapid and anisotropic adsorption and desorption of water vapor by a flexible dynamic element which harnesses the chemical potential across very small humidity gradients for perpetual motion can be effectively modulated with light. A mechanically robust material capable of rapid exchange of water with the surroundings was prepared that undergoes swift locomotion in effect to periodic shape reconfiguration with turnover frequency of <150 min−1. The element can lift objects ~85 times heavier and can transport cargos ~20 times heavier than itself. Having an azobenzene-containing conjugate as a photoactive dopant, this entirely humidity-driven self-actuation can be controlled remotely with ultraviolet light, thus setting a platform for a new generation of smart biomimetic hybrids. The actuating material can operate in the dark and could be utilized to convert the humidity into electrical power in low-power devices driven by humidity and/or light.