Dielectric Studies of Bi2MoO6/Graphene Oxide and La-Doped Bi2MoO6/Graphene Oxide Nanocomposites

The mixed metal oxides Bi2MoO6 and La-doped Bi2MoO6 were prepared by the sol–gel method. Then, varying quantities of the as-prepared mixed metal oxides were blended with graphene oxide (GO), employing sonication, to obtain Bi2MoO6/GO (BM/GO) and La-Bi2MoO6/GO (LBM/GO) nanocomposites. These prepared materials were characterized by different techniques such as thermal gravimetric analysis (TGA), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and transmission electron microscopy (TEM). Dielectric properties were studied by using a precision impedance analyzer. Dielectric constant and loss tan of the synthesized composites were studied as a function of frequency by using a precision impedance analyzer. Overall, the dielectric constant (ɛ’) observed for the LBM/GO composites was higher than that of BM/GO.

Utilizing Impedance for Quality Assessment of European Squid (Loligo Vulgaris) during Chilled Storage

This study evaluates the quality of chilled squid Loligo vulgaris by non-destructive measurements of bioelectrical impedance from the first post-mortem day under controlled conditions. Squid samples were stored at 4.5 °C and 55% of relative humidity for 11 days. Impedance magnitude (|Z|) and phase (φ) at 200 frequencies (100Hz to 100MHz) were measured using an Agilent 4294A Precision Impedance Analyzer with needle-type multi-electrode array on days 1, 2, 3, 4, 5, 8, 9, 10, and 11 of storage. The changes in color, sensory properties, total volatile nitrogen, pH, and water holding capacity were also determined. The obtained results indicated that the samples could be classified into five to six distinctive groups by measuring the electrical parameters at frequencies close to 5MHz. In general, φ is less dependent on temperature and measurement setup than |Z|, while records at 5MHz correlate well with the days of storage (R2 = 0.968). The data imply that it is only possible to estimate the length of storage for the samples with measurements of phase angle, which can be useful for the development of new analytical instruments. Biosensors have a practical industrial application, as it is demonstrated that bioelectrical impedance data correlates well with the days of chilled storage.

Electrical System for Bioelectric Impedance using AD5933 Impedance Converter

Benchtop lab equipment, such as the HP4194A Precision Impedance Analyzer, offer accuracy and functionality but are often expensive and bulky. Although integrated circuits offer less functionality than benchtop equivalents, they can be a cheaper alternative for smaller applications. In this study, the AD5933 Impedance Converter was investigated as a low-cost option for impedance analysis of the bicep brachii. The AD5933 evaluation board was properly calibrated to measure human muscle by using an equivalent parallel circuit consisting of a 5 nF capacitor and a 1 kOhm resistor. Next, the impedance of the bicep was measured using the AD5933 as the experimental device and the HP4194A as the control device. A 2 volt peak-to- peak signal was generated for a 10 kHz to 100 kHz frequency range and the resulting impedance of the bicep was measured. The AD5933 recorded impedance curves qualitatively and quantitatively similar to those recorded by the HP4194A. Thus, the AD5933 was considered to be a low- cost alternative for impedance analysis in small-scale medical applications.

Electro-Mechanical Impedance (EMI) Based Interlayer Slide Detection Using Piezoceramic Smart Aggregates—A Feasibility Study

Interlayer slide damage is one of the main causes of landslide hazard, inflicting huge economic losses and casualties. It is urgent to accurately detect the initiation and development of the interlayer slide damage in real time. In this paper, a study on the feasibility of using the electro-mechanical impedance (EMI) technique to detect the interlayer slide damage was presented. The main purpose of this paper is to investigate the application of the EMI technique for interlayer slide detection using piezoceramic smart aggregates (SAs). In the experimental study, three small landslide specimens with a weak interlayer in the middle were fabricated. For each specimen, three piezoceramic SAs were post-embedded at specific positions, which were located above the weak interlayer inside the structure. The specimens were subjected to a compressive test to initiate an interlayer slide along the weak layer. The whole loading process was monitored with a precision impedance analyzer by measuring the admittance (reciprocal of impedance) of the SAs over time. The statistic metrics, including root mean square deviation (RMSD) and mean absolute percentage deviation (MAPD), were introduced to quantify the variations in admittance signatures due to interlayer slide damage. It was found that the admittance signatures and statistic metrics were sensitive to the interlayer slide damage. The experimental results verify the feasibility and practicality of using EMI technique to detect the interlayer slide.

Damage Monitoring Research of the Concrete Structure Based on the Piezoelectric Impedance

Based on the piezoelectric impedance technology, damages in concrete specimens could be monitored. The structural damages were simulated by pasting piezoelectric ceramic chips and boring several holes on the surface of concrete specimens. And then, with the precision impedance analyzer HP4192A, we measured the conductance spectrum curve of the specimens.The specimens were in two different damage situations：one was damaged in one place to varying degrees and the other was damaged in different locations to the same degree. The experiment results show that the damages in the specimens can lead to the drift of the conductance spectrum curve and the greater the damages are, the greater the change will be.

Low Temperature Sintering of (Ba0.98Ca0.02)(Sn0.04Ti0.96)O3 Ceramics Using CuO-B2O3 as a Sintering Additive

The effects of CuO-B2O3(CBO) additive on densification, microstructure, and electrical properties of (Ba0.98Ca0.02)(Sn0.04Ti0.96)O3(BCST) cermaics were investigated. The phase compositions, microstructure, dielectric, ferroelectric and piezoelectric properties of BCST ceramics were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), precision impedance analyzer, ferroelectric tester and quasi-static piezoelectric constant testing meter, respectively. The results show that CuO-B2O3(CBO) frit can improve the densification and promote low-temperature sintering of BCST ceramics prepared by a conventional solid-state reaction method. Dense BCST ceramics with CBO can be sintered at temperatures as low as 1175 °C, which is approximately 275 °C less than the sintering temperature of pure BCST. When sintered at 1200 °C, the optimized properties of the BCST ceramics with 0.5 wt% CBO were obtain asε= 1206,d33= 346 pC/N,kP= 0.39, tgδ = 0.009.

Ground Surface Deformation Sensor Based on Cable Impedance

In order to measure ground surface deformation, a sensor based on cable impedance change is studied in this paper. This sensing cable has elastic double helical structure with much larger measurement range than optical fiber distributed deformation technology. Using the precision impedance analyzer, we obtain the relationship between elongation and impedance of the sensing cable and choose one of the frequent as the measurement frequency. A ground surface deformation measuring circuit is designed for the sensing cable. Deformation experiment shows that the relationship between sensing cable impedance and stretching deformation is approximately linearity, when the deformation is small.