scholarly journals Design of a High Sensitivity Microwave Sensor for Liquid Dielectric Constant Measurement

Sensors ◽  
2020 ◽  
Vol 20 (19) ◽  
pp. 5598
Author(s):  
Honggang Hao ◽  
Dexu Wang ◽  
Zhu Wang ◽  
Bo Yin ◽  
Wei Ruan
Keyword(s):  
Dielectric Constant ◽  
Resonant Frequency ◽  
High Sensitivity ◽  
Dielectric Substrate ◽  
Frequency Offset ◽  
Liquid Dielectric ◽  
Microwave Sensor ◽  
Constant Measurement ◽  
Dielectric Constant Measurement ◽  
First Time

In order to improve the sensitivity of liquid dielectric constant measurements, a liquid dielectric constant sensor based on a cubic container structure is proposed for the first time. The cubic container, which consists of a dielectric substrate with a split resonant ring (SRR) and microstrip lines, can enhance the electric field intensity in the measuring area. High sensitivity can be obtained from measuring the dielectric constant with the characteristics of the structure resonate. The research results show that the resonant frequency of the sensor is shifted from 7.69 GHz to 5.70 GHz, with about a 2 GHz frequency offset, when the dielectric constant of the sample varied from 1 to 10. A resonance frequency offset of 200 MHz for the per unit dielectric constant is achieved, which is excellent regarding performance. The permittivity of oil with a different metal content is measured by using the relation between the fitted permittivity and the resonant frequency. The relative error is less than 1.5% and the sensitivity of measuring is up to 3.45%.

scholarly journals CSRR-SICW High Sensitivity High Temperature Sensor Based on Si3N4 Ceramics

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 459
Author(s):  
Shujing Su ◽  
Ting Ren ◽  
Lili Zhang ◽  
Fujia Xu
Keyword(s):  
Dielectric Constant ◽  
High Temperature ◽  
Resonant Frequency ◽  
Real Time ◽  
Temperature Sensor ◽  
Circular Waveguide ◽  
High Sensitivity ◽  
Dielectric Substrate ◽  
Test Sensitivity ◽  
High Temperature Sensor

A new type of wireless passive, high sensitivity, high temperature sensor was designed to meet the real-time temperature test in the harsh aero-engine environment. The sensor consists of a complementary split ring resonator and a substrate integrated circular waveguide (CSRR-SICW) structure and is based on high temperature resistant Si3N4 ceramic as the substrate material. Temperature is measured by real-time monitoring of the resonant frequency of the sensor. In addition, the ambient temperature affects the dielectric constant of the dielectric substrate, and the resonant frequency of the sensor is determined by the dielectric constant, so the function relationship between temperature and resonant frequency can be established. The experimental results show that the resonant frequency of the sensor decreases from 11.3392 GHz to 11.0648 GHz in the range of 50–1000 °C. The sensitivity is 123 kHz/°C and 417 kHz/°C at 50–450 °C and 450–1000 °C, respectively, and the average test sensitivity is 289 kHz/°C. Compared with previously reported high temperature sensors, the average test sensitivity is approximately doubled, and the test sensitivity at 450–1000 °C is approximately three times higher. Therefore, the proposed high sensitivity sensor has promising prospects for high temperature measurement.

scholarly journals Complex Permittivity Characterization of Liquid Samples Based on a Split Ring Resonator (SRR)

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3385
Author(s):  
Jialu Ma ◽  
Jingchao Tang ◽  
Kaicheng Wang ◽  
Lianghao Guo ◽  
Yubin Gong ◽  
...  
Keyword(s):  
Resonant Frequency ◽  
Complex Permittivity ◽  
Ring Resonator ◽  
High Sensitivity ◽  
Split Ring Resonator ◽  
Debye Model ◽  
Split Ring ◽  
Liquid Samples ◽  
Microwave Sensor

A complex permittivity characterization method for liquid samples has been proposed. The measurement is carried out based on a self-designed microwave sensor with a split ring resonator (SRR), the unload resonant frequency of which is 5.05 GHz. The liquid samples in capillary are placed in the resonant zone of the fabricated senor for high sensitivity measurement. The frequency shift of 58.7 MHz is achieved when the capillary is filled with ethanol, corresponding a sensitivity of 97.46 MHz/μL. The complex permittivity of methanol, ethanol, isopropanol (IPA) and deionized water at the resonant frequency are measured and calibrated by the first order Debye model. Then, the complex permittivity of different concentrations of aqueous solutions of these materials are measured by using the calibrated sensor system. The results show that the proposed sensor has high sensitivity and accuracy in measuring the complex permittivity of liquid samples with volumes as small as 0.13 μL. It provides a useful reference for the complex permittivity characterization of small amount of liquid chemical samples. In addition, the characterization of an important biological sample (inositol) is carried out by using the proposed sensor.

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