Real Time Microwave Biochemical Sensor Based on Circular SIW Approach for Aqueous Dielectric Detection

Abstract

In this study, a critical evaluation of analyte dielectric properties in a microvolume was undertaken, using a microwave biochemical sensor based on a circular substrate integrated waveguide (CSIW) topology. These dielectric properties were numerically investigated based on the resonant perturbation method, as this method provides the best sensing performance as a real-time biochemical detector. To validate these findings, shifts of the resonant frequency in the presence of aqueous solvents were compared with an ideal permittivity. The sensor prototype required a 2.5 µL volume of the liquid sample each time, which still offered an overall accuracy of better than 99.06%, with an average error measurement of ±0.44%, compared with the commercial and ideal permittivity values. The unloaded Q u factor of the circular substrate-integrated waveguide (CSIW) sensor achieved more than 400 to ensure a precise measurement. At 4.4 GHz, a good agreement was observed between simulated and measured results within a broad frequency range, from 1 to 6 GHz. The proposed sensor, therefore, offers high sensitivity detection, a simple structural design, a fast-sensing response, and cost-effectiveness. The proposed sensor in this study will facilitate real improvements in any material characterization applications such as pharmaceutical, bio-sensing, and food processing applications.

Novel Metamaterials-Based Hypersensitized Liquid Sensor Integrating Omega-Shaped Resonator with Microstrip Transmission Line

“…Results had shown that the resonance frequency depends strongly on aqueous solvents, whereby high unloaded, Q factor of about 400 was achieved using the circular substrate-integrated waveguide (CSIW) sensor. This proposed structure can be a promising candidate for application of bio sensing and food processing [29]. The metamaterials based on omega shaped resonator have been investigated by other researchers, however their studies are mainly focused on the metamaterial concept [30,31].…”

Radio-Frequency Biosensors for Real-Time and Continuous Glucose Detection

“…A planar SIW has advantages of a planar resonator, such as being compact, cost-effective, and more straightforward to fabricate than a cavity, but a large sample volume is still required [ 74 ]. To solve this problem, a 2-port circular SIW with a microfluidic subsystem for glucose concentration detection has been proposed [ 75 ]. The resonant frequency of the circular SIW is 4.4 GHz, and the transmission coefficient and Q-factor at the resonant frequency are −4.63 dB and 419, respectively.…”

Design of an ELC resonator-based reusable RF microfluidic sensor for blood glucose estimation

“…To analyze the sensitivity across all the sensor variants, the relative permittivity, , of a lossless test sample placed over the central arm of the resonator, is varied over a wide range and the resultant loaded resonant frequency, , is observed. The normalized frequency shifts, , where is the sensor’s unloaded resonant frequency, are then compared to ensure a fair assessment as it is known that a sensor’s higher resonant frequency in itself could be a partial contributing factor towards achieving more significant frequency shift and thus higher sensitivity 47 , 48 . Figure 3 a shows the unloaded resonant frequencies of the sensors.…”