Interdigital Capacitor Based Microwave Heater for Continuous Microfluidics

In this work, an interdigital capacitor (IDC) topology on Quartz substrate is employed for microwave heating at 25 GHz for picolitre volumes in continuous microfluidics (CMF). The electrodes of the IDC heater are designed using COMSOL Multiphysics to achieve rapid, contact-less and uniform heating. The CMF channel is manufactured using polydimethylsiloxane and bonded to the quartz wafer. The manufactured device is tested using simultaneous microwave excitation, temperature measurements and optical investigation. A mixture of deionized water and a fluorescent dye, Rhodamine B, is used to evaluate the heating performance of the manufactured device. A temperature increase of 20.2°C is achieved after 10 ms of heating with 1 W of power at 25 GHz.