Author:

Keywords:

microfluidics, microvalve, photopolymerization, responsive hydrogels, Science & Technology, Technology, Physical Sciences, Materials Science, Multidisciplinary, Physics, Applied, Physics, Condensed Matter, Materials Science, Physics, SENSITIVE HYDROGELS, FLOW-CONTROL, BIOMEDICAL APPLICATIONS, SENSOR, DEVICES, ISFET, LAB, MICROSENSORS, MICROSYSTEM, COPOLYMERS, 0204 Condensed Matter Physics, 0912 Materials Engineering, 1007 Nanotechnology, Applied Physics, 4016 Materials engineering, 4018 Nanotechnology, 5104 Condensed matter physics

Abstract:

Two types of microvalves based on temperature-responsive poly(N-isopropylacrylamide) (PNIPAAm) and pH-responsive poly(sodium acrylate) (PSA) hydrogel films have been developed and tested. The PNIPAAm and PSA hydrogel films were prepared by means of in situ photopolymerization directly inside the fluidic channel of a microfluidic chip fabricated by combining Si and SU-8 technologies. The swelling/shrinking properties and height changes of the PNIPAAm and PSA films inside the fluidic channel were studied at temperatures of deionized water from 14 to 36 °C and different pH values (pH 3-12) of Titrisol buffer, respectively. Additionally, in separate experiments, the lower critical solution temperature (LCST) of the PNIPAAm hydrogel was investigated by means of a differential scanning calorimetry (DSC) and a surface plasmon resonance (SPR) method. Mass-flow measurements have shown the feasibility of the prepared hydrogel films to work as an on-chip integrated temperature- or pH-responsive microvalve capable to switch the flow channel on/off. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.