Ultrasensitive miniaturized planar microwave sensor for characterization of water–alcohol mixtures

Abstract

Designing a low-cost, compact, yet sensitive planar microwave sensor for complex permittivity measurement is highly desired for numerous applications though quite challenging. Here, in this research, an ultrasensitive planar microwave sensor is proposed which is based on an electric LC structure. The core sensor was fabricated on an FR-4 substrate using a simple fabrication process, then integrated within a polymethylmethacrylate microfluidic channel for straightforward liquid delivery to the sensing region. The resonance frequency of the bare sensor was designed to occur at 4.14 GHz while empty and shifted to 0.88 GHz when deionized water flows into the channel. The sensor response has been characterized for different mixture ratios of methanol and ethanol with deionized water. Next, the complex permittivity of the resulted binary mixtures has been extracted by the Debye model through a least square fitting method. The calculated average sensitivity is 1.45% which stands above most of sensors reported in the literature. Besides, the sensor has a small footprint with dimensions of 3.6 × 3.8 mm$$^2$$ 2 making it a suitable candidate for integration with point-of-care testing devices.

Graphene based T‐shaped monopole antenna sensor for food quality evaluation

“…In a microstrip patch antenna, electromagnetic radiation occurs from the radiating patch to the substrate due to a fringing field effect from the radiating patch 37,38 . Hence, the performance of the patch sensor is affected directly by the permittivity of the substrate and the shape and size of the radiating patch 39,40 . The performance of the microstrip antenna depends upon several characteristics of the radiating patch because they change the resonant frequency of the antenna.…”

“…37,38 Hence, the performance of the patch sensor is affected directly by the permittivity of the substrate and the shape and size of the radiating patch. 39,40 The performance of the microstrip antenna depends upon several characteristics of the radiating patch because they change the resonant frequency of the antenna.…”