Everything is Illuminated: Photopolymerization Yields Stomata-Inspired Membrane
Hydrogels have been widely used in tissue engineering, biofabrication, and other technologies. Prof. Sang Joon Lee and graduate student Hyejeong Kim of the Department of Mechanical Engineering at POSTECH have fabricated a stomata-inspired membrane (SIM) with fine pores from a temperature-responsive hydrogel after using the process of patterned photopolymerization. This SIM could potentially be applied to numerous engineering applications in the future. Their research was recently published in Advanced Functional Materials.
Stomata are minute pores distributed on the leaf’s surface. They are like what noses are for humans and animals. A pair of guard cells open and close the stomata on plant leaves or stem epidermis, which function as multisensory valves that open and close to exchange water and gas between a plant and its environment.
In this study, Prof. Lee and Ms. Kim mimic the gating function of stomata by using a temperature-responsive hydrogel. The pre-gel solution of hydrogel was covered with a photomask and illuminated by UV-light. By adjusting UV-light exposure and the photomask pattern, a distinct double-parted membrane with pores was created by single illumination. The pores open and close their aperture when triggered by a slight temperature change.
In contrast to previous work that fabricated hydrogel actuators which were mostly made with bilayers of different materials, the present study used a single material to synthesize an actuating membrane. The use of a single material in double-parted actuators eliminates any risk of delamination. In addition, the morphological configuration of the SIM can be easily controlled by changing the photomask for a specific application.
Similar to stomatal movement, the developed membrane is an intelligent membrane that can sense and react to environmental changes. As the membrane features the sensing-to-actuation functions of stimuli-responsive hydrogels and can be easily fabricated, it can be used in numerous practical applications, including temperature responsive filter membranes, smart valves, and membrane-based diagnosis devices.