Fast Light-Driven Motion of Polydopamine Nanomembranes

Area of Science:

• Nanotechnology
• Materials Science
• Photonics

Background:

• Actuation of micro- and nanostructures by external stimuli is crucial for applications in energy harvesting, robotics, sensing, biomedicine, and tunable metamaterials.
• Photoactuation offers remote and spatiotemporal control by converting light into motion via reversible processes.

Purpose of the Study:

• To report fast light-to-motion conversion in few-nanometer thick bare polydopamine (PDA) membranes.
• To demonstrate PDA membranes as multiresponsive materials for nanoscale actuators.

Main Methods:

• Utilized visible light to stimulate bare polydopamine (PDA) membranes.
• Measured contraction and expansion times in response to light stimuli and dissipation.

Main Results:

• Achieved light-induced contraction in less than 140 μs due to light-induced heating and water desorption.
• Observed spontaneous expansion in less than 20 ms upon switching off light, attributed to heat dissipation and water adsorption.

Conclusions:

• Pristine PDA membranes exhibit rapid photoactuation.
• These membranes are robust, multiresponsive building blocks for soft, micro-, and nanoscale actuators responding to light, temperature, and moisture.