Decrease In Capacitance Value Research Articles

Integration of fully printed and flexible organic electrolyte-based dual cell supercapacitor with energy supply platform for low power electronics

We report the fabrication of flexible, printed dual cell supercapacitors (DCSCs) and their implementations in energy storage units providing peak power to portable devices. The use of organic electrolytes enhances higher capacity in both potential windows (2.5 V/cell) and the temperature ranges than the aqueous electrolytes, while propylene carbonate retains the advantages of low cost and low toxicity. The device delivered capacitance value between 3 and 4 mF, equivalent series resistance < 2 Ω, and very low leakage current of about 0.1 µA. We demonstrated the integration of an organic photovoltaic module (OPV) with an energy supply platform (ESP) and DCSCs for indoor light energy harvesting and storage. The maximum harvested energy was about 39 mJ. The energy is sufficient to provide peak power to portable devices and sensors. This was confirmed by powering an LED with our energy harvesting system. Mechanical deformation testing of DCSCs shows excellent mechanical stability, so that the device is well suited for flexible energy storage units. In a long-term cyclic stability test, the decrease in capacitance value was only 1% of the initial value after 10,000 cycles, indicating good durability and performance.

Influence of Magnetic Field on the Electrodeposition and Capacitive Performances of MnO2

This study focuses on the influence of an applied external magnetic field on the electrodeposition process and capacitive performances of MnO2, as pseudo-capacitive active material for supercapacitors electrodes. MnO2 was electrochemically deposited on Si/Au substrates in the presence and in the absence of a 0.5 T magnet, and its capacitive performance was tested via electrochemical characterization. The samples obtained in the presence of the magnetic field show a positive influence on the deposition process: the increase in deposition efficiency leads to more compact and uniform MnO2 coatings, with a decrease in capacitance values for the samples produced with the magnetic field.

Investigation of Synthesized Sulfonated Melamine Formaldehyde as a Novel Corrosion Inhibitor for Mild Steel in Saline Environment

A water soluble compound named sulfonated melamine formaldehyde (SMF) was synthesized and its corrosion inhibition behavior was studied for carbon steel in 3.5% NaCl solution by polarization measurements and electrochemical impedance spectroscopy (EIS). SMF was characterized with hydrogen nuclear magnetic resonance spectroscopy and then its physical properties and corrosion prevention efficiencies were investigated. The corrosion behavior of SMF was found to be dependent strongly on the electric nature of functional groups which are present in its structure. The decrease in (icorr) and the increase in inhibition efficiency (% IE) with increasing the SMF concentrations proves that it protects C-steel in 3.5% NaCl solution from being corroded and Nyquist diagrams indicate that increasing charge transfer resistance is associated with a decrease in the capacitance and increase in the percentage inhibition efficiency. The decrease in capacitance values could be attributed to the adsorption of the inhibitor molecules at the metal surface by increasing the concentration of inhibitor in the solution the inhibition efficiency increased and the best inhibition was obtained at 1000 ppm inhibitor concentration. The scanning electron microscope was used to investigate the surface morphology of specimens in the absence and presence of inhibitor compound.

46.4: Self‐Aligned Bottom‐Gate Amorphous IGZO Thin Film Transistor using the Back Side Exposure Technique

AbstractIn this work, we proposed new fabrication equipment for using the back side exposure technique in Gen.8 glass size and discussed a self‐alignment technique for fabrication of a‐IGZO TFTs which result in inverted staggered bottom gate devices, to simplify the OLED array processing. The Cgs of a‐IGZO TFTs with back side exposure process was lower about 40% than that of a a‐IGZO TFTs with typical process. The decrease in capacitance value of the back side exposure process a‐IGZO TFTs is because the overlap area between the gate and source/drain electrodes has become decrease. At Vds of 10V, the back side exposure process a‐IGZO TFTs represent μsat of 12.43 cm2/Vs, Vth of 0.75V, on‐current of 74.4uA, S‐Factor of 0.23V/dec.

Gamma radiation effects in capacitance of alpha alumina doped with rare earths

This paper presents the study of the gamma radiation influence on the dielectric properties of alpha-alumina doped with rare earths. The work deals with the possibility of determine the absorbed dose by capacitance measurements of the material. The samples were synthesized by sol–gel processes and Pechini, and best dopant concentration value was determined based on data from samples that supplied better behavior for luminescence dosimetry. A decrease in capacitance values with increasing radiation doses was experimentally verified. Ionization process produced excited charges carries, which are trapped in metastable states, which can change the characteristics of the dielectric alpha-alumina sample.

The Inherent Capacitance of Moisturising Creams: A Source of False Positive Results?

The capacitance is a frequently used measurement of skin hydration in vivo, therefore any potential for false capacitance results is of importance. This in vitro study is to investigate the capacities of moisturising creams to cause false positive results. Adding different volumes of demineralised water and saline on dry clean plastic-backed tissue paper and measuring the capacitance values, the standard relation curve of capacitance value and volume of water was established. Four moisturising creams, petrolatum, a protective cream and a gel were then applied to the same kind of tissue paper in constant volumes, and were measured for weights and capacitance values over a 1-hour period allowing the gradual evaporation of water and volatile elements. A positive linear relationship was found between volume of water and capacitance value. All the creams had inherent capacitance that correlated with their water content. The inherent capacitance of creams decreased over time and ultimately reached comparable low values. The decrease in capacitance correlated significantly with weight reduction, except for petrolatum, which showed negligible inherent capacitance and weight reduction. The rates of decrease in capacitance value versus cream weight were significantly different for different creams. The results assured that capacitance value correlates to water content, and the inherent capacitance of creams may contribute to false positive skin capacitance in vivo if measured before water and other volatile elements of creams evaporate from the skin surface. In addition, the inherent capacitance and its durability may be relevant characteristics for further comparative studies of moisturisers and their clinical efficacy.