title: Acoustothermal heating of polydimethylsiloxane microfluidic system.
abstract: We report an observation of rapid (exceeding 2,000 K/s) heating of polydimethylsiloxane (PDMS), one of the most popular microchannel materials, under cyclic loadings at high (~MHz) frequencies. A microheater was developed based on the finding. The heating mechanism utilized vibration damping in PDMS induced by sound waves that were generated and precisely controlled using a conventional surface acoustic wave (SAW) microfluidic system. The refraction of SAW into the PDMS microchip, called the leaky SAW, takes a form of bulk wave and rapidly heats the microchannels in a volumetric manner. The penetration depths were measured to range from 210 μm to 1290 μm, enough to cover most sizes of microchannels. The energy conversion efficiency was SAW frequency-dependent and measured to be the highest at around 30 MHz. Independent actuation of each interdigital transducer (IDT) enabled independent manipulation of SAWs, permitting spatiotemporal control of temperature on the microchip. All the advantages of this microheater facilitated a two-step continuous flow polymerase chain reaction (CFPCR) to achieve the billion-fold amplification of a 134 bp DNA amplicon in less than 3 min.
authors.affiliation: Department of Mechanical Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Korea.
authors.forename: Byung Hang
authors.initials: BH
authors.lastname: Ha
authors.affiliation: Department of Mechanical Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Korea.
authors.forename: Kang Soo
authors.initials: KS
authors.lastname: Lee
authors.affiliation: Department of Mechanical Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Korea.
authors.forename: Ghulam
authors.initials: G
authors.lastname: Destgeer
authors.affiliation: Department of Mechanical Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Korea.
authors.forename: Jinsoo
authors.initials: J
authors.lastname: Park
authors.affiliation: Department of Mechanical Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Korea.
authors.forename: Jin Seung
authors.initials: JS
authors.lastname: Choung
authors.affiliation: Department of Mechanical Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Korea.
authors.forename: Jin Ho
authors.initials: JH
authors.lastname: Jung
authors.affiliation: Department of Mechanical Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Korea.
authors.forename: Jennifer Hyunjong
authors.initials: JH
authors.lastname: Shin
authors.affiliation: Department of Mechanical Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Korea.
authors.forename: Hyung Jin
authors.initials: HJ
authors.lastname: Sung