Polyaniline was synthesized chemically. The purified form of polyaniline was swollen with THF before dispersing in N-methyl pyrrolidone for film making. The thickness of the films were 80 and 100 micrometers. Polyaniline films were doped with hydrochloric acid at two different concentrations for varied periods of time. The doped films with areas of 1 cm2 were used as conducting plates, and papers were soaked with paraffin as dielectric of conducting polyaniline capacitor. In the present work design, construction of capacitor based on conducting polyaniline films has been investigated experimentally. The results of measurement and calculation of capacitance of the designed capacitor, assuming that diffusion of dopant in polyaniline is plate-like, arc reported. Stability under both atmospheric and vacuum conditions were investigated. Experimental results and theoretical studies show that by increasing the doping time, capacitance is increased. Also, the thinner insulating form of polyaniline film, the faster the two conducting fronts meet and the capacitor reaches a maximum. The value of this maximum in the present work was 42PF.

Electrical Capacitance Tomography (ECT) is an imaging technique that maps the electrical permittivity contrast of the object. This paper studies an image and a shape reconstruction method for ECT. For image reconstruction, a regularized Gauss-Newton method has been implemented, based on the inverse finite element technique. For shape reconstruction, a . narrow band level set method has been developed. Using experimental ECT data, a comparative study of these two techniques is the main objective of this paper.

Water is one of the most vital constituents in plants. In this research, for an estimation of leaf moisture content, the variation of capacitance was employed. The variations were measured via designed and manufactured capacitive sensors. The objective of the research was to estimate leaf moisture content by measuring its capacitance for five agronomic crops. Experiments for measuring leaf capacitance were performed on maize, sorghum, capsular bean, white bean and sunflower at two frequencies of: 100 kHz and 1 MHz. The results showed that in all cases the best fitted curve for variations of the capacitance in relation to leaf moisture percentage was in the form of an exponential function namely: y= aebx (where y is capacitance, x is leaf moisture content, a is the linear coefficient, and b is the exponential coefficient). Parameters a and b for different plants of each crop and each frequency were not significantly different at 1% probability level. However, these coefficients were significantly different among different crops. Coefficients of determination were higher at 100 kHz than at 1 MHz. It was also observed that the higher the leaf moisture the more the data points scattered around the best-fit line, although the scattering was more uniform at 1 MHz.

The graphene (GR) has attracted intensive interest due to its two-dimensional and unique physical properties. In the present study, the graphene sheets were synthesized by electrochemical exfoliation of graphite in sulfuric acid solution. The polybithiophene-graphene (PbTh-GR) composite films deposited onto indium tin oxide substrate (ITO/PbTh-GR) have been prepared by the incorporation of graphene sheets into the PbTh matrix during electropolymerization under magnetic stirring from the LiClO4/CH3CN electrolyte containing the bithiophene (bTh) monomer and graphene sheets. The incorporation of graphene sheets at different masses (1, 2 and 3 mg) is ensured by the effect of the stirring of the electrolyte. The characterisation of films is effected by electrochemical methods (cyclic voltammetry and impedance spectroscopy), spectroscopic technics (FT-IR, UV-Visible), X ray diffraction, thermogravimetric analysis, and scanning electron microscopy. It was observed that the electrochemical performance measurements of the ITO/PbTh-GR (3 mg) film show a specific capacity of around 65 F/g, which is six times higher than that of ITO/PbTh films, 11 F/g.

This paper presents a high-precision capacitance-to-digital converter (CDC) based on period-modulation (PM) for grounded capacitive sensors. In this work, with a symmetrical design, the performance of the proposed capacitance to digital converter is significantly improved by applying zoom-in and three signal auto-calibration techniques. The dominant nonidealities of the CDC circuit are located at the three asymmetrical phases of the auto-calibration pathes. These effects are investigated here which are mainly caused by charge injection of switches and associated parasitic effects. These nonidealities are reduced by utilizing dummy switches at asymmetrical paths of the applied auto-calibration. The proposed interface is designed as an integrated circuit using a standard 0.18μm CMOS technology. A worst-case capacitance error less than 0.2fF for a 10pF sensor capacitor with maximum variation of 200fF, and parasitic capacitance of up to 20pF is obtained. The CDC achieves an absolute capacitance resolution of 0.479fF across a 10pF sensor capacitance with a 200fF variation, corresponding to an energy efficiency of 6.94pJ/step. The achieved latency is 128µs and the CDC consumes 170µA from a 2V power supply.

In designing a parallel resonant induction heating system, choosing a proper capacitance for the resonant circuit is quite important. The capacitance affects the resonant frequency, output power, heating efficiency and power factor. In this paper, with consideration to function of the equivalent series resistance (ESR), optimal capacitance is calculated.The induction heating resonance capacitor is achieved using Smart Bacteria Foraging Algorithm (SBFA) under voltage and frequency constraints for minimizing cost function that is including: increasing the output power and efficiency of an induction heater, while decreasing the power loss of the capacitor. The proposed algorithm mimics chemotactic behavior of E. Coli bacteria to optimize parameters. The proposed algorithm enjoys individual and social intelligence, so that it can search influx ways among hidden layers of the problem. Based on the equivalent circuit model of an induction heating system, the output power, and the capacitor losses are calculated. The effectiveness of the proposed method is verified by computer simulations, also improving the obtained results using SBFA are compared to classical bacteria foraging algorithm BFA.

Introduction: Determining working length is regarded as an important step in root canal treatment, for which electronic apex locator can be applied. New apex locators are preferred, since they work via applying alternating current. Furthermore, the two factors of dentin specific resistance and capacitance seem to be effective principles in their operating. Therefore, this study aimed to determine and compare the dentin capacitance in young and old teeth.Methods: In order to glean the study data, 60 human permanent teeth were collected consisting of 30 permanent teeth under twenty-five years and 30 permanent teeth over sixty year. The sixty samples of same dimensions were prepared from mid levels of the teeth roots. The capacitance circuit rates created in three frequencies of 100 HZ, 1KHZ and 10KHZ were measured. Moreover, in order to analyze the study data, ANOVA and Mann-Whitney tests were utilized.Results: The mean value of capacitance circuit teeth under twenty five years and over sixty years respectively involved 60 and 137 in 100HZ, 2.5 and 9.5 in 1KHZ and 0.05 and 0.3 in 10KHZ, which this difference was proved to be statistically significant (P Value =0.000) Conclusion: The study findings revealed a different capacitance between young and old teeth. Regarding the influence of this factor in the operating principle of apex locators, calibrate the device may be necessitated while applying it in young and old teeth.

Grading based on product ripeness is important for marketing fruits and vegetables. Various methods have been used to determine fruit ripeness some of which are destructive and some nondestructive. In this study for determining the fruit ripeness of apple during storage an apparatus was designed and fabricated to measure the electrical capacitance of the fruit samples as an indication of fruit ripeness. In the next stage a model was proposed to establish a relationship between the capacitance and ripeness (maturity rate) of the apple fruits. The capacitance unit was used to measure the dielectric constant of two apple varieties; Red delicious and Golden Delicious. For each variety three fruit samples of 45 mature apples were harvested on one day. Each sample was divided into three groups of small, medium and large apples. Preliminary tests indicated that the capacitance unit can establish a good relationship between dielectric constant and fruit ripeness at a frequency of 100 kHz. Remaining tests were conducted to measure dielectric constants of all samples under controlled conditions of temperature and humidity at this frequency. Analyses of the results indicated that dielectric constant decreases as the fruit ripens. This frequency level was also used to conduct other tests for measuring the fruit hardness and total soluble solids (TSS) during ripening stage. Results indicated that fruit hardness decreases and TSS increases during ripening.