Fabrication method and performance of a light-responsive hydrogel microvalve in a microfluidic chip

Microfluidic technology has potential advantages in the complex manipulation of microfluidics on small-sized chips. However, it is difficult to integrate microvalves with complex flow channel structures, and this has limited the miniaturization of microfluidic systems and their portable applications. Light-responsive hydrogel (LRH) materials can rapidly change their volume under laser irradiation and can be used to prepare flexible microvalves to realize the integrated control of microfluidics. A simple fabrication method for an LRH microvalve on a microfluidic chip is proposed. The microspheres, as control elements of the microvalve based on an LRH modified with Laponite RD nanoclay and ferriferous oxide (Fe₃O₄) nanoparticles, are prepared through a T-shaped flow channel. The microvalve is assembled on the microfluidic chip with a normally closed circulation channel. The open/close performance of the microvalve is represented by the color change of the photonic crystal material. The results show that the LRH microspheres shrink and the flow channel opens after laser irradiation for 2 s. After stopping the laser at 18 s, the valve core swells and the flow channel closes.