Abstract
In this study, a high-Q circular substrate-integrated waveguide (SIW) cavity resonator is proposed as a non-contact and non-invasive radio frequency (RF) sensor for chemical sensing applications. The design of the structure utilizes SIW technology along with a circular shape to achieve a high unloaded Q factor, which is one of the important requirements for RF sensors. The resonant frequency of the proposed circular SIW cavity sensor changes when a liquid material or a chemical (microliters) is inserted in the sensitive area of the structure. The sensing of liquid materials with different permittivities is accomplished via the perturbation of the electric fields in the SIW configuration. When a microwell that is 4 mm in radius is installed vertically through the center of the bare circular SIW cavity, the operating frequency varies from 5.26 to 5.34 GHz. Similarly, when the microwell contains ethanol, the frequency shifts from 5.26 to 5.18 GHz, and the amplitude of reflection coefficient is shifted from −29 dB to −17 dB; when the microwell contains mixing deionized (DI)-water, the frequency moves from 5.26 to 4.98 GHz (which is also 0% Ethanol in our study), and the amplitude of reflection coefficient is shifted from −29 dB to −8 dB. A high unloaded Q factor is maintained throughout all experimental results. To demonstrate our idea, different concentrations of ethanol are tested and recorded. The experimental validation yields a close agreement between the simulations and the measurements.
Highlights
Chemical sensors have been used for many years to identify the purity ranks of numerous fluids to simplify the arrangement of those fluids for a wide range of industrial applications
A microfluidic microwell made of PDMS is installed at the most subtle location configuration
A microfluidic microwell made of PDMS is installed at the most subtle location ofThe the proposed is constructed on a Rogers/Duroid material typical printed circuit board (PCB)
Summary
Chemical sensors have been used for many years to identify the purity ranks of numerous fluids to simplify the arrangement of those fluids for a wide range of industrial applications. It is necessary to store and classify these fluids or chemicals in accordance with the Globally Harmonized System of Classification and Labelling of Chemicals. The use of unidentified and unlabeled chemicals in experiments may have unforeseen consequences, and some of these chemicals may have severe effects on the human body. Methyl alcohol is toxic to the skin and body and can cause blindness, unconsciousness, and even death [1]. Fluidic chemical materials should be labeled so that they are recognized properly. A material safety manual should always be provided to the experimenters
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