Microfluidic Valve Employing the pH-Responsive Hydrogel Microsphere as an Actuating Element

In this paper, we propose a new fabrication method of pH-responsive microfluidic valves and suggest the feasibility as a microminiature systems without peripheral devices. Conventionally, in-situ photopolymerization method has been employed to build the micro functional structure inside microfluidic channel. Here, we suggest a new method allowing the mass production of stimuli-responsive microsystem through the use of pre-made microstructure as actuating element like assembly of commercial products in the factory. We have massively fabricated pH-responsive microspheres that act as actuating component through the use of PDMS-based microfluidic apparatus and 'on the fly' photopolymerization method. By the incorporation of this microsphere into the microvalve during the fabrication process, we have produced the pH-responsive microfluidic valve in a simple way. The operation and the function of the fabricated microvalve were evaluated through the diverse experiments. The microvalve was successfully fabricated, and functioned well according to the pH change