Microwave Dual Heater for Independent Heating of Liquid Samples

Abstract

This work presents a novel microwave heater pair designed for the independent and simultaneous heating of two liquid samples in microfluidic channels. The device is based on two resonators operating at distinct frequencies, enabling scalable heating within a single-feedline configuration. Experimental results demonstrate the system's ability to achieve target temperatures between 30°C and 60°C with minimal temperature overshoot of below $4\%$. The heater's performance is evaluated in two modes; in individual mode, the device selectively heats one sample while maintaining a lower temperature in the other, whereas, in simultaneous mode, the two resonators work in tandem to heat both samples. In individual heating mode, heating rates of 25.5°C/s and 17.5°C/s were achieved for the first and the second heater, respectively. Similarly, the simultaneous mode obtained heating rates of 10.6°C/s and 7.6°C/s. This work establishes an efficient platform for selective microwave heating, with potential chemical and biomedical applications.

Keywords: Dielectric heating, frequency-selective heating, microfluidics, microwave heating, resonators, temperature control