ملخص البحث :

The nutritional benefits of milk and its widespread consumption make drinking only fresh and healthy milk important. Safely consuming milk necessitates differentiating between fresh and spoiled milk, which can lead to stomach disturbance and food-borne illness. Researchers and the food industry work hard to maintain milk quality by devising techniques to impede spoilage and determine the duration for how long milk remains fresh. In this study, three different split-ring microstrip resonators (multi-SRRs) with passive elements were planned and fabricated on printed circuit boards (PCD). Each resonator operated at a separate resonant frequency: 3, 4, and 5 GHz with amplitudes of −10.91, −11.53, and −26.26 dB, respectively. The simulation and experimental results were identical when the sensor was tested by placing a Petri dish covering its upper surface. To better understand the lifespan of fresh buffalo milk, we investigated it in a controlled setting. This sensor was used to study how long fresh milk remains suitable for use. For 14 h, we analyzed the resonant amplitude variations ( Δ Amplitude) and monitored pH levels to estimate shelf life. The maximum rate of resonant amplitude change was found by calculating the slope of the linear model representing shelf life during the initial 8 h. The calculated values were 0.588, 0.361, and 0.159 dB/h, respectively, each with high coefficients of determination. The instrument can discern between fresh milk with a pH of 6.85–6.57 and spoiling milk (pH 6.57–5.46). Our results showed that the sensor had high-resolution and nondestructive monitoring capabilities, with results that closely agreed with pH meter readings and microscopic images.

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In this study, a microwave active antenna sensor (MAAS) was designed and manufactured from PCB boards operating at a frequency of approximately 3 GHz to sense the characteristics of mineral oils (high voltage transformer oils) and chemical liquids such as methanol, chloroform, and ethanol. The proposed sensor has been designed using the automation software system named ADS (advanced design system). The antenna was linked with a radio amplifier; therefore, the antenna is called active antenna. As a result, the reflection coefficient changed from − 39.98 dB to − 66.26 dB, and also the quality factor changed from 350 to 27,000. The measuring and simulation results were quite identical in both active and passive antenna cases. An M-shaped channel with a capacity of 150 μL was built on a microscope glass slide, where the glass slide was placed in contact with the above face of the designed antenna (near field). That a slit channel was placed on the areas in which the electric field is concentrated. Then, the sensor was tested by injecting the channel with new and damaged transformer oil. Despite the small sample size, the amount of resonant frequency change was 2.23 MHz and 1.48 MHz for the active and passive antennas, respectively. A mathematical model was built to calculate the breakdown voltage of high voltage transformer oil, and the error value in the breakdown voltage value did not exceed ± 0.1606%. The other application of the antenna is to sense chemical liquids and to calculate the electrical permittivity of those samples by finding a mathematical model based on the resonant properties of the antenna. The measured permittivity of the liquids have been compared with the theoretical values, which gives a good qualitative agreement for our results.

ملخص البحث :

This work suggests a microwave resonator sensor (MRS) device for measuring the oil’s breakdown voltage of high voltage transformers. A precise high-sensitivity sensor is designed and manufactured based on a microstrip split ring resonator (SRR). To improve the sensor sensitivity, a radio frequency (RF) amplifier of 30 dB gain is linked through a transmission line of 50Ω. The sensor operates at a microwave band (L) with a quality factor of 1.35 × 105 when it is loaded with an empty tube. In this work, the sensor has been tested with three samples of high voltage transformer oil of different ages (new, middle, and damaged) where the quality factor differs with each sample. A mathematical model was built to calculate the breakdown voltage of the transformer oils and the accuracy of the results was higher than 90%.

ملخص البحث :

This study presents a wireless electromagnetic sensing system based on the resonant properties of the star-fractal antenna. Thus, it has been used for measuring the complex electrical permittivity of sodium sulfite solutions, according to both transmission and reflection efficiencies of the incident electromagnetic wave. The proposed antenna has been designed and simulated using the HFSS-Software (Ansoft High-Frequency Structure Simulator). The optimum resonant dimensions of the designed star-fractal antenna are (24.5 × 23 × 1.64) mm with a dielectric substrate (ε = 2.2). The proposed antenna operates on a single band applications, at frequency 2.4 GHz. Based on this antenna, several parameters have been calculated, such as the return loss, input impedance, and radiation patterns. Therefore, in this study, the designed antenna was used to fabricate a sensor to measure the electrical properties of liquids that depend on its concentrations. Thus, the various high concentrations of Na2SO3 solution (1–5) mol/L, were sensitized. Which were compared with the theoretical results using a special mathematical model to calculate the electrical properties of each concentration. Consequently, the good qualitative agreement results were measured for the real and imaginary parts of the complex permittivity at 99% and 92%, respectively.

ملخص البحث :

ملخص البحث :

The sensor is designed to operate at frequency of 1.4 GHz and quality factor of 360. The sensor has been tested with several solvents to verify its sensitivity where the resonant frequency and losses vary with each solvent. The shift in the resonant frequency and the change in the insertion loss have been used to extract the values of the complex permittivity of the solvent. The measured complex permittivities of the solvents have been compared with the theoretical values with very good agreement. This sensor can be utilized in many industrial and medical application where the characterization of liquids are needed.

ملخص البحث :

Stopband split ring resonator (SSRR) is presented in this paper for measuring complex permittivity of liquid with different position of microfluidic channel operates at resonant frequency of 1 GHz. The sensor was fabricated and microfluidic channel is located in the gap groove with two different positions of the carrier where the electric field is as large as possible. The sensor has been tested with several solvents to verify its sensitivity where the electric field interacts with the liquid filled in a quartz tube and hence alter the SRR behavior. The electromagnetic properties (complex permittivity) of the solvent can be extracted from shift in the resonant frequency of the resonator due to perturbation phenomenon.