title: Photogated humidity-driven motility.
abstract: Hygroinduced motion is a fundamental process of energy conversion that is essential for applications that require contactless actuation in response to the day-night rhythm of atmospheric humidity. Here we demonstrate that mechanical bistability caused by rapid and anisotropic adsorption and desorption of water vapour by a flexible dynamic element that 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 is 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 next-generation smart biomimetic hybrids.
authors.affiliation: New York University Abu Dhabi, PO Box 129188, Abu Dhabi, United Arab Emirates.
authors.forename: Lidong
authors.initials: L
authors.lastname: Zhang
authors.affiliation: New York University Abu Dhabi, PO Box 129188, Abu Dhabi, United Arab Emirates.
authors.forename: Haoran
authors.initials: H
authors.lastname: Liang
authors.affiliation: Abu Dhabi University, PO Box 59911, Abu Dhabi, United Arab Emirates.
authors.forename: Jolly
authors.initials: J
authors.lastname: Jacob
authors.affiliation: New York University Abu Dhabi, PO Box 129188, Abu Dhabi, United Arab Emirates.
authors.forename: Panče
authors.initials: P
authors.lastname: Naumov