Development and evaluation of microwave microfluidic devices made of polydimethylsiloxane

A transparent, optically observable microfluidic device for microwave-induced chemical reactions using 24.125 GHz ISM band incorporating was developed. The microfluidic channels can pass through gaps in the post-wall waveguide. The post-wall waveguide allows microwave irradiation to be applied to designed area of the microfluidic channel. In this study, Polydimethylsiloxane (PDMS), commonly used in microfluidic devices, was used as the microwave waveguide material. A glass plate sputtered with indium tin oxide was used to shield microwave leakage to the top and bottom. 4 W of microwave input power was used to heat ethylene glycol, which is used as a solvent in chemical synthesis, in the channels of the fabricated device, and a temperature rise to 100 °C was observed in 70 s. We believe that the use of PDMS as a waveguide material will facilitate observation during microwave irradiation using optics and combination with other microreactors.