Photoresponsive polymer gel microvalves controlled by local light irradiation

This paper presents independent control of multiple microvalves, which are opened by local light irradiation. The application of photoresponsive polymer gel. which was developed by our research group, to photoresponsive microvalve was systematically examined. Photoresponsive polymer which were composed of poly(N-isopropylacrylamide) functionalized with spirobenzopyran chromophore (pSPNIPAAm), were fabricated by in situ photo-polymerization at the desired positions in microchannels. Blue light irradiation to the pSPNIPAAm gels induced shrinkage of the gels and caused the microvalves composed of the gels to open. Local light irradiation to the discrete microvalves enabled independent control of three photoresponsive polymer gel microvalves, which had been fabricated on a single microchip. Each microvalve was opened by 18-30s light irradiation. (c) 2007 Elsevier B.V. All rights reserved.