Molecular design of light-responsive hydrogels, for in situ generation of fast and reversible valves for microfluidic applications

J. Schiphorst, ter, S. Coleman, J.E. Stumpel, A. Ben Azouz, D. Diamond, A.P.H.J. Schenning

Research output: Contribution to journalArticleAcademicpeer-review

88 Citations (Scopus)
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Abstract

Reversible light-responsive hydrogel valves with response characteristics compatible for microfluidics have been obtained by optimization of molecular design of spiropyran photoswitches and gel composition. Self-protonating gel formulations were exploited, wherein acrylic acid was copolymerized in the hydrogel network as an internal proton donor, to achieve a swollen state of the hydrogel in water at neutral pH. Light-responsive properties were endowed upon the hydrogels by copolymerization of spiropyran chromophores, using electron withdrawing and donating groups to tune the gel-swelling and shrinkage behavior. In all cases, the shrinkage was determined by the water diffusion rate, while for the swelling the isomerization kinetics is the rate-determining step. For one hydrogel, reversible and reproducible volume changes were observed. Finally, gel-valves integrated within microfluidic channels were fabricated, allowing reversible and repeatable operation, with opening and closing of the valve in minutes.
Original languageEnglish
Pages (from-to)5925-5931
JournalChemistry of Materials
Volume27
Issue number17
DOIs
Publication statusPublished - 2015

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