Yoon, DS Cho, YK Oh, KW Kim, S Kim, YA Han, JI Lim, G 2024-01-21T03:38:35Z 2024-01-21T03:38:35Z 2022-01-10 2006-02 0946-7076 https://pubs.kist.re.kr/handle/201004/135765 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 degrees C to 50-60 degrees 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 degrees C while keeping the temperature of the flowing microchannel below 35 degrees 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 mu l/min. The gel valve device showed no leakage up to 2.07x10(4)supercript stop Pa. English SPRINGER HEIDELBERG POLYMERASE-CHAIN-REACTION GELATION METHYLCELLULOSE THERMOGELATION A microfluidic gel valve device using reversible sol-gel transition of methyl cellulose for biomedical application Article 10.1007/s00542-005-0051-5 1 MICROSYSTEM TECHNOLOGIES-MICRO-AND NANOSYSTEMS-INFORMATION STORAGE AND PROCESSING SYSTEMS, v.12, no.3, pp.238 - 246 MICROSYSTEM TECHNOLOGIES-MICRO-AND NANOSYSTEMS-INFORMATION STORAGE AND PROCESSING SYSTEMS 12 3 238 246 scie scopus 000234875200007 2-s2.0-31144472416 Engineering, Electrical & Electronic Nanoscience & Nanotechnology Materials Science, Multidisciplinary Physics, Applied Engineering Science & Technology - Other Topics Materials Science Physics Article POLYMERASE-CHAIN-REACTION GELATION METHYLCELLULOSE THERMOGELATION methyl cellulose sol-gel gel valve BioMEMS