A hydrogel-actuated microvalve for smart flow control

In this paper, we report on the fabrication and testing of a hydrogel-actuated smart microvalve for biomedical applications. The three-layered microvalve is composed of a stimuli-sensitive "intelligent" hydrogel sandwiched between a porous silicon membrane and a bossed PDMS flexible diaphragm. The entrapped hydrogel in response to changes in the external physiological stimuli (e.g., pH, glucose, etc.), which diffuses through the porous membrane, swelles and deswelles hence deflecting the flexible PDMS diaphragm and controlling the closure and opening of the microvalve inlet. A microvalve incorporating a 155mum thick hydrogel (poly(methacrylic acid-co-acrylamide), mAA-co-AAm) has a response time of 3.6min to a sudden pH change (pH=3 to pH=7).