A microfluidic gel valve device using reversible sol–gel transition of methyl cellulose for biomedical application |
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Authors: | Dae Sung Yoon Yoon-Kyoung Cho Kwang W Oh Sunhee Kim Young Ah Kim Jung Im Han Geunbae Lim |
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Affiliation: | (1) Bio-MEMS Laboratory, Microsystem Research Center, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul, 130-650, Korea;(2) Digital Bio Laboratory, Samsung Advanced Institute of Technology, P.O. Box 111, Suwon, Kyunggi-do, Korea;(3) Department of Chemistry, Surface Science Center, University of Pittsburgh, Pittsburgh, PA 15260, USA;(4) Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, Kyungbook, Korea |
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Abstract: | We have fabricated a microfluidic gel valve device that used reversible sol–gel transition of methyl cellulose (MC). A microheater
and a microtemperature sensor were implemented in each microchannel in the gel valve device. Before evaluating the performance
of the gel valve device, various properties of the MC solution were investigated using viscometer, spectrophotometer, and
NMR. Gelation temperature was increased as the MC concentration was increased. Clear gel, an intermediate state between clear
sol and turbid gel, was found at the temperature range from 30–40°C to 50–60°C. Temperature at each microchannel of the device
was measured and the effect of the temperature difference on the valve operation was elucidated. In order to have normal operation
of the gel valve, it was important to keep the temperature of the heated microchannel around 60°C while keeping the temperature
of the flowing microchannel below 35°C. The temperature difference between two microchannels was about 23 K when fan forced
cooling (FFC) method was used. For normal performance of the gel valve device, a temporary pause of fluid flow for at least
5 s was required to complete the local gelation in the microchannel. Stable gel valve performance was obtained at the flow
rates larger than 5 μl/min. The gel valve device showed no leakage up to 2.07×104 Pa. |
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Keywords: | Methyl cellulose Sol– gel Gel valve BioMEMS |
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