posted on 2021-12-14, 15:49authored byThomas Vasileiadis, Tommaso Marchesi D’Alvise, Clara-Magdalena Saak, Mikolaj Pochylski, Sean Harvey, Christopher V. Synatschke, Jacek Gapinski, George Fytas, Ellen H. G. Backus, Tanja Weil, Bartlomiej Graczykowski
The actuation of
micro- and nanostructures controlled by external
stimuli remains one of the exciting challenges in nanotechnology due
to the wealth of fundamental questions and potential applications
in energy harvesting, robotics, sensing, biomedicine, and tunable
metamaterials. Photoactuation utilizes the conversion of light into
motion through reversible chemical and physical processes and enables
remote and spatiotemporal control of the actuation. Here, we report
a fast light-to-motion conversion in few-nanometer thick bare polydopamine
(PDA) membranes stimulated by visible light. Light-induced heating
of PDA leads to desorption of water molecules and contraction of membranes
in less than 140 μs. Switching off the light leads to a spontaneous
expansion in less than 20 ms due to heat dissipation and water adsorption.
Our findings demonstrate that pristine PDA membranes are multiresponsive
materials that can be harnessed as robust building blocks for soft,
micro-, and nanoscale actuators stimulated by light, temperature,
and moisture level.