Search
Menu
CASTECH INC - New Building the Bridge of Light

Light Alters Film’s Degree of Wetness

Facebook X LinkedIn Email
David Shenkenberg

Researchers at Pohang University of Science and Technology in South Korea have developed a film that can become wet or dry upon exposure to different wavelengths of light. Eventually, it could serve as a biosensor, a microfluidic device or an intelligent membrane.

TWSwitch_Reversible_Film.gifTo make the material, the scientists alternately deposited layers of positively charged poly(allylamine hydrochloride) and negatively charged silicon dioxide nanoparticles on a silicon wafer, and the opposing charges enabled them to self-assemble. Then they coated the resulting material with a photoswitchable agent.

For 10 minutes, the scientists focused 365-nm UV radiation onto the film through holes patterned on an aluminum mask. The UV-exposed regions of the material rapidly absorbed water in shapes like those on the mask (see figure). Shining visible light onto the film made those areas dry again, effectively erasing the patterns.

Based on scanning electron microscopy and atomic force microscopy experiments, the researchers believe that UV radiation reduces the contact area between the photoswitchable agent and water, exposing the porous, underlying chemical layers to water.

Journal of the American Chemical Society, published online Oct. 21, 2006, 10.1021/ja0655901.
PI Physik Instrumente - Revolution In Photonics Align ROS MR 3/24

Published: December 2006
Glossary
nano
An SI prefix meaning one billionth (10-9). Nano can also be used to indicate the study of atoms, molecules and other structures and particles on the nanometer scale. Nano-optics (also referred to as nanophotonics), for example, is the study of how light and light-matter interactions behave on the nanometer scale. See nanophotonics.
photonics
The technology of generating and harnessing light and other forms of radiant energy whose quantum unit is the photon. The science includes light emission, transmission, deflection, amplification and detection by optical components and instruments, lasers and other light sources, fiber optics, electro-optical instrumentation, related hardware and electronics, and sophisticated systems. The range of applications of photonics extends from energy generation to detection to communications and...
Basic Scienceintelligent membranemicrofluidic deviceMicroscopynanophotonicsPohang University of Science and TechnolotyResearch & TechnologySensors & DetectorsTech Pulse

We use cookies to improve user experience and analyze our website traffic as stated in our Privacy Policy. By using this website, you agree to the use of cookies unless you have disabled them.