Structural, optical, electric and dielectric characterization of a NaCu0.2Fe0.3Mn0.5O2 compound

The compound NaCu0.2Fe0.3Mn0.5O2 was synthesized using a solid-state method and it crystallized in a hexagonal system with a R3̄m space group in an O3-type phase.

Elaboration of a piezoelectric force sensor for medical application

In this work, a piezoelectric force sensor was fabricated based on Lead-Free ferroelectric particles (Na0.535K0.48)0.966 Li0.058 Nb0.9Ta0.1O3 (NKLNT) synthesized by solid-state route. A piezoelectric characterization by FTIR spectroscopy and dielectric characterization was performed. The manufactured NKLNT sensor shows excellent sensitivity and response to external mechanical forces, which implies that this sensor presents a promising technology for different applications.

Differential microwave sensor based on microstrip lines loaded with a split-ring resonator for dielectric characterization of materials

In this work, we propose a microwave sensor that allows the characterization of dielectric materials based on a differential configuration. A microstrip permittivity sensor of the surrounding material is proposed using a split ring-resonator to measure differentially. The geometry was optimized and was numerically analyzed using CST STUDIO. The numerical analysis of the metamaterial unit cells is carried out first, to determine the operating band. After that, the metamaterial cell was employed to design the differential microstrip permittivity sensor. The obtained results reveal that the proposed sensor has the capability to characterize different materials whose relative dielectric permittivity’s are in the range of 9.8 to 80 with great performance. The device has a total size of 86 mm × 60 mm and operates around 3 GHz. In this band, the sensor reaches a sensibility of 2.89 MHz and a Q-factor of 70.15. Thus, this work shows a compact, reusable, label-free, and non-destructive microwave sensing device and paves the way for high accuracy sensing of the dielectric properties of different materials due to its high- Q-factor as well as high sensitivity.

Influence of Tire Rubber Particles Addition in Different Branching Degrees Polyethylene Matrix Composites on Physical and Structural Behavior

Waste from pneumatic wheels is one of the major environmental problems, and the scientific community is looking for methods to recycle this type of waste. In this paper, ground tire rubber particles (GTR) from disused tires have been mixed with samples of low-density polyethylene (LDPE) and high-density polyethylene (HDPE), and morphological tests have been performed using scanning electron microscopy (SEM), as well as the dynamic electric analysis (DEA) dielectric characterization technique using impedance spectroscopy. From this experience, how GTR reinforcement influences polyethylene and what influence GTR particles have on the branched polyethylene has been detected. For pure LDPE samples, a Debye-type dielectric behavior is observed with an imperfect semicircle, which depends on the temperature, as it shows differences for the samples at 30 °C and 120 °C, unlike the HDPE samples, which do not show such a trend. The behavior in samples with Debye behavior is like an almost perfect dipole and is due to the crystalline behavior of polyethylene at high temperature and without any reinforcement. These have been obtained evidence that for branched PE (LPDE) the Maxwell Wagner Sillars (MWS) effect is highly remarkable and that this happens due to the intrachain polarization effect combined with MWS. This means that the permittivity and conductivity at LDPE/50%GTR are high than LDPE/70%GTR. However, it does not always occur that way with HDPE composites in which HDPE/70%GTR has the highest values of permittivity and conductivity, due to the presence of conductive fraction (Carbon Black-30%) in the GTR particles and their dielectric behavior.

High-Q Active Microwave Sensor Based on Microstrip Complementary Split-Ring Resonator (MCSRR) Structure for Dielectric Characterization

This paper presents an active microwave sensor for the characterization of dielectric materials. The sensor is consisted of a microstrip complementary split-ring resonator (MCSRR) structure and an active feedback loop. The loop uses an amplifier to generate negative resistance to compensate the resonator’s loss and increase the loaded quality factor. The developed sensor possesses the advantages of high quality factor, ultra-small electrical size, and high sensitivity. A prototype of the sensor is fabricated and measured for validation.

A Metamaterial-Inspired Microwave Sensor for Dielectric Characterization of Organic Liquids and Solid Dielectric Substrates

A microwave metamaterial-inspired sensor based on a 13×13 arrays of Asymmetric Electric Split-Ring Resonator (AESRR) is proposed for dielectric characterization of organic liquids and solid dielectric substrates with low permittivity. The sensor, excited by a pair of patch antennas and working at around 11.575 GHz, is fabricated using printed circuit board (PCB) technology. T-shape channel was integrated to the sensor by grooving in the FR-4 substrate which improved the integration and provided the feasibility of liquids detection. Seven liquids and four dielectric substrates are measured by this sensor. The measured results show the transmission frequency shifts from 11.575 GHz to 11.150 GHz as the liquid samples permittivity changes from 1 to 7 and the transmission frequency shifts from 11.575 GHz to 8.260 GHz as the solid substrates permittivity changes from 1 to 9. The measured results have proven the improved sensitivity and the larger frequency shift ∆f on material under test (MUTs) compared with the conventional reported sensor. The relative permittivity of liquid samples and solid samples can be fitted by establishing approximate models in CST, respectively. Two transcendental equations derived from measured results are proposed to predict the relative permittivity of liquid samples and solids samples. The accuracy and reliability of measured results and predicted results are numerically verified by comparing them with literature values. The proposed sensor has many advantages, such as low-cost, high-sensitivity, high-robustness, and extensive detecting range, which provided a great potential to be implemented in a lab-on-a-chip sensor system in the future.

A comparative review of the main techniques for electromagnetic characterization of materials / Uma revisão comparativa das principais técnicas de caracterização eletromagnética de materiais

This paper presents the main techniques of electromagnetic characterization electromagnetic at microwave frequency. A detailed analysis of these is performed, indicating which materials under test (MUT) can be measured with the specific technique. Additionally, for the dielectric characterization, measurement results are presented with the best technique that suits this case.