Simultaneous Detection of Two Chemicals Using a TE20-Mode Substrate-Integrated Waveguide Resonator

Abstract

Microwave resonators working as sensors can detect only a single analyte at a time. To address this issue, a TE20-mode substrate-integrated waveguide (SIW) resonator is exploited, owing to its two distinct regions of high-intensity electric fields, which can be manipulated by loading two chemicals. Two microfluidic channels with unequal fluid-carrying capacities, engraved in a polydimethylsiloxane (PDMS) sheet, can perturb the symmetric electric fields even if loaded with the two extreme cases of dielectric [ethanol (E), deionized water (DI)] and [deionized water, ethanol]. The four layers of the sandwiched structure considered in this study consisted of a top conductive pattern and a bottom ground, both realized on a Rogers RT/Duroid 5880. PDMS-based channels attached with an adhesive serve as the middle layers. The TE20-mode SIW with empty channels resonates at 8.26 GHz and exhibits a −25 dB return loss with an unloaded quality factor of Q ≈ 28. We simultaneously load E and DI and demonstrate the detection of the four possible combinations: [E, DI], [DI, E], [E, E], and [DI, DI]. The performance of our proposed method showed increases in sensitivity (MHz/εr) of 7.5%, 216%, and 1170% compared with three previously existing multichannel microwave chemical sensors.

Multi-Band Sensing for Dielectric Property of Chemicals Using Metamaterial Integrated Microfluidic Sensor

“…Moreover, since different mixtures may have the same frequency shift, measurements at a fixed frequency can only distinguish chemicals by frequency shift, which limits the reliability of the identification. For dual frequency measurement methods, it indeed promotes the efficiency of measuring concentrations and enables the measurement of chemicals at different frequencies, allowing for the discrimination of chemicals based on frequency shift at different frequencies 29 , 30 . However, previously published work did not establish a relationship between resonant parameters and dielectric characteristics to distinguish chemicals from their dielectric properties.…”

“…Moreover, with the increase in the number of resonators in the sensor, the sensor can realize the multi-band sensing of dielectric property of chemicals, which enhances its potential in practical applications. In addition, compared with other chemical sensor using metamaterial absorber 29 , the MIM sensor possesses smaller sample volumes (~4 µL), more miniaturized size (24*15*0.6 mm 3 ) and better linearity in ethanol sensing (−2.80%).…”

Low-Cost and Lightweight 3D-Printed Split-Ring Resonator for Chemical Sensing Applications

“…Q factors are estimated from S 21 curves (simulations and measurements) based on 3 dB bandwidth criterion such that Q = f r /Δ f 3dB [ 22 , 23 ]. Relative error in resonance frequency was estimated from the difference between the corresponding simulations and measurements [ 24 , 25 ].…”

Design of Substrate-Integrated Waveguide Loading Multiple Complementary Open Resonant Rings (CSRRs) for Dielectric Constant Measurement

“…The dielectric constant of a substance is an important characteristic parameter that characterizes the electromagnetic properties of a material. Accurate measurement of the dielectric constant is particularly important in the development, production, and use of microwave dielectric materials [1][2][3][4][5][6]. Traditional methods for measuring the dielectric constant mainly include the transmission line method, waveguide method, free space method, neural network method, and resonant cavity method [7][8][9][10][11][12][13].…”