A polymeric microfluidic valve employing a pH-responsive hydrogel microsphere as an actuating source

In this paper, we propose a new fabrication method for pH-responsive microfluidic valves. Conventionally, an in situ photopolymerization method has been employed to build the micro functional structure inside a microfluidic channel. Here, we suggest a new method that allows the mass production of a stimuli-responsive microsystem through the use of a pre-made microstructure as an actuating element, like the assembly of commercial products in a factory. We have massively fabricated pH-responsive microspheres that act as an actuating component through the use of PDMS-based microfluidic apparatus and an 'on the fly' photopolymerization method. By incorporation of this microsphere into the microvalve during the fabrication process, we have produced a pH-responsive microfluidic valve in a simple way. The operation and the function of the fabricated microvalve were evaluated through diverse experiments. The microvalve was successfully fabricated, and functioned well according to the pH change.