Microwave Sensors Based on Coplanar Waveguide Loaded with Split Ring Resonators: A Review

This article reviews the application of physical, chemical and biological sensing of materials via microwave sensors based on a coplanar waveguide (CPW) loaded with a split ring resonator (SRR). Many CPWs loaded with SRR structures from the literature are reviewed in this article. CPWs loaded with many shapes of resonators have been proposed, such as circular, square and rectangular-shaped SRRs and CSRRs based on a paired and an array, folded stepped impedance (SIR), square and circular electric – LC (ELC) SRRs, circular, square, rectangular and golden ratio spiral S-shaped SRRs, diamond-shaped tapered SRRs, horn-shaped SRRs and others. The working principle for each device is briefly described and compared. The strength of this article is to introduce the application of microwave sensors based on CPWs loaded with SRRs for measurement and characterization of physical, chemical and biological materials through electromagnetic interaction

Glucose Concentration Monitoring Using Microstrip Spurline Sensor

This article reports a microstrip spurline sensor for glucose concentration monitoring. The microstrip spurline sensor is a low-cost and easy-to-fabricate device that uses printed circuit board (PCB) technology. It consists of a combination of four spurlines and transmission lines. The four spurlines are used to reject unwanted frequencies, while the transmission lines allow the desired frequencies to pass through. The resonance frequency (Fr) and reflection coefficient (S11) were recorded through meticulous simulations and experiments over a frequency range from 1.5 GHz to 4 GHz. In addition, the sensor was used to detect changes in glucose concentration, ranging from 0 mg/dL to 150 mg/dL. The findings of this study show that the antenna-based sensor proposed in this research can effectively measure glucose levels across the diabetes range, from hypoglycemia to normoglycemia to hyperglycemia, with a high degree of sensitivity of 7.82 x 10−3 dB/(mg/dL) and 233.33 kHz/(mg/dL)

Narrow-Band Light-Emitting Diodes (LEDs) Effects on Sunflower (Helianthus annuus) Sprouts with Remote Monitoring and Recording by Internet of Things Device

Previous studies have demonstrated that light quality critically affects plant development and growth; however, the response depends upon the plant species. This research aims to examine the effects of different light wavelengths on sunflower (Helianthus annuus) sprouts that were stimulated during the night. Natural light and narrow-band light-emitting diodes (LEDs) were used for an analysis of sunflower sprouts grown under full light and specific light wavelengths. Sunflower seeds were germinated under different light spectra including red, blue, white, and natural light. Luminosity, temperature, and humidity sensors were installed in the plant nursery and remotely monitored and recorded by an Internet of Things (IoT) device. The experiment examined seed germination for seven days. The results showed that the red light had the most influence on sunflower seed germination, while the natural light had the most influence on the increase in the root and hypocotyl lengths

Multi-resonators, microwave microfluidic sensor for liquid characterization

In this paper, a new type of microwave microfluidic sensor is presented, using three separate half wave microstrip resonators with a common junction. The sensor comprises three parallel resonators with resonant frequencies of 2.5, 3.5, and 4.5 GHz. This sensor exhibits all the usual advantages of microwave resonant methods for dielectric liquid characterization, such as high precision, accuracy, and sensitivity, but here also over a wideband of frequencies. The resonators have common input and output ports. The sensor was tested using several types of liquids, including water, methanol, ethanol, and chloroform, and experimental results are in excellent agreement with the simulation results