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.
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机译：我们报告了在高频（〜MHz）循环负载下快速（超过2,000 K / s）加热聚二甲基硅氧烷（PDMS）（一种最流行的微通道材料）的现象。基于这一发现开发了一个微型加热器。加热机制利用了由声波引起的PDMS中的振动阻尼，该声波是使用常规表面声波（SAW）微流体系统生成并精确控制的。 SAW进入PDMS微芯片的折射称为泄漏SAW，其形式为体波，并以体积方式快速加热微通道。测得的穿透深度范围为210μm至1290μm，足以覆盖大多数尺寸的微通道。能量转换效率取决于声表面波的频率，在30 MHz附近测得最高。每个叉指换能器（IDT）的独立致动实现了声表面波的独立操纵，从而允许时空控制微芯片上的温度。该微型加热器的所有优点促进了两步连续流聚合酶链反应（CFPCR），可在不到3分钟的时间内实现134 bp DNA扩增子的十亿倍扩增。
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