Loop Antenna Driven Double Microwave Resonator-Based Sensors Incorporating PDMS Microchannels on Glass Substrates

Abstract

Microwave resonator-based sensors offer low-cost, contactless, label-free sensing solutions in a variety of applications. Sensing is done by the observation of the shifts in resonant frequency of the sensor structure, which depends on resonator geometry, material and physical properties of the environment. It is observed that the readings can be significantly affected by changes in secondary physical parameters or sample localization on resonator. A double microwave resonator sensing system incorporating microchannels on glass substrates are proposed to address these challenges. PDMS microchannels bonded on glass substrates are mounted on split ring resonators fabricated via low-cost processes. Experiments are performed with glucose solutions of 1.4 mg/mL–3.0 mg/mL concentration range. Results confirm that the use of double resonators increase rejection of background noise, whereas microchannel use increases measurement stability. Overall measurement sensitivity is shown to be 0.92 MHz/(mg/mL). Further improvements are aimed with the bonding of microchannels directly on resonators fabricated on glass substrates.