Molecular Design of Light-Responsive Hydrogels, For in Situ Generation of Fast and Reversible Valves for Microfluidic Applications

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• 作者：Jeroen ter Schiphorst ; Simon Coleman ; Jelle E. Stumpel ; Aymen Ben Azouz ; Dermot Diamond ; Albertus P. H. J. Schenning
• 刊名：Chemistry of Materials
• 出版年：2015
• 出版时间：September 8, 2015
• 年：2015
• 卷：27
• 期：17
• 页码：5925-5931
• 全文大小：424K
• ISSN：1520-5002

文摘

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.