关键词: 聚N-异丙基丙烯酰胺, 温控微阀, 微流控芯片, 流动注射分析

Abstract: Poly(N-isopropylacrylamide)(PNIPAAm) undergoes a rapid phase transition at its lower critical solution temperature(32 ℃), leading to sharp changes in its volume and surface wettability. The thermally responsive volume change behavior of the PNIPAAm can be used to manipulate the microfluids in microchannels. In the present work, PNIPAAm monolithic plugs, serving as the thermally actuated microfluidic valve, were prepared by photoinitiated polymerization within the channels of a glass chip. Photo-polymerization of the N-isopropylacrylamide monomer in water/ethanol was carried out using 2-hydroxy-2-methyl propiophenone as the photo-initiator. The polymerization conditions for the thermally actuated microfluidic valve and its fluid-manipulating behavior were systematically investigated. Based on these investigations, a protocol of on-chip-integrated micro-flow injection(μFIA) system equipped with a single thermally actuated microfluidic valve was established. The analytical performance of the μFIA system was demonstrated with the chelating reaction between the magnesium(Ⅱ) and the fluorescent agent O,O'-dihydroxyazobenzene. Experimental results show that the mirofluidic valve behaved well for the flow control and was promising in the field of microfluidics.

Key words: Poly(N-isopropylacrylamide), Thermally actuated microfluidic valve, Microfluidic chip, Flow injection analysis