Membrane blocks gas when illuminated by purple light

It is said to be the first time that scientists have developed a membrane that can be controlled by light in this way.

Eric Glowacki, a graduate student at the university’s Laboratory for Laser Energetics, and Kenneth Marshall, his adviser, invented the membrane, which is a piece of plastic punctured with tiny holes that are filled with liquid crystals and a dye.

When purple light illuminates the surface of the membrane, the dye molecules straighten and the liquid crystals fall into line, which allows gas to flow through the holes.

When ultraviolet light illuminates the surface, the dye molecules bend into a curved shape and the liquid crystals scatter into random orientations, clogging the tunnel and blocking gas from penetrating.

Controlling a membrane’s permeability with light is preferable to controlling it with heat or electricity for several reasons, according to Glowacki. Light can operate remotely, so instead of attaching electrical lines to the membrane, a lamp or a laser can be directed at the membrane from a distance. This could allow engineers to make much smaller, simpler setups.