Variation Of Potential Difference Research Articles

Bioinspired Potentiometric and Passive Strain Sensing Based on Mechanical Regulation of Ionically Conductive Percolating Networks

AbstractFlexible strain sensors are essential components for wearable devices, human‐machine interaction systems, and intelligent soft robots. Current active strain sensors have high power consumption, while passive strain sensors exhibit limitations in detecting static or slowly‐varying stimulations. Here, inspired by the strain sensing behavior of Ruffini endings in natural skin, a new type of potentiometric, fully passive, and highly stretchable strain sensors are presented based on the mechanical regulation of ionically conductive percolating networks. Specifically, an artificial potential difference is first created with two electrochemical active electrodes, followed by encoding external strain stimulations into the potential difference variations using a new class of highly elastic and ionically conductive composites with configurable ionic percolating networks. Based on the proposed passive strain sensing mechanism, both static and slowly‐varying strain stimulations (up to 100%) can be monitored with ultralow power consumption (at nW level). Promising applications of the passive strain sensors in human motion monitoring, Morse code communication, and hand gesture recognition are demonstrated. This work opens up a new avenue to constructing novel strain sensing devices with high stretchability, ultralow power consumption, and desirable sensing performance.

Facile construction of electrochemical and self-powered wearable pressure sensors based on metallic corrosion effects

Flexible mechanical sensors are essential components for smart wearables. Conventional resistive, capacitive, or transistor-based mechanical sensors consume energy continuously, while piezoelectric and triboelectric sensors respond selectively to dynamic or transient mechanical stimulations. Developing mechanical sensors that do not necessitate external power supply but are able to monitor static mechanical stimuli can compensate for the deficiencies of existing sensing devices. Here, we present the facile construction of a new paradigm of electrochemical mechanical sensors based on ubiquitous metallic corrosion effects. The intrinsic differences in corrosion activities of diverse metals (e.g., zinc, aluminum, copper, etc.) are utilized to create potential differences between two electrodes, followed by encoding external mechanical stimulations into the potential difference variations via carefully selected solid electrolytes. The developed electrochemical mechanical sensors exhibit comparable performance (e.g., sensitivity, recovery/response speed, reproducibility, etc.) with that of conventional sensors, but possess significantly superior simplicity, cost-efficiency, and desirable capability in resolving static or slowly-varying mechanical stimulations in a self-powered manner. As proof-of-concept demonstrations, machine learning enabled speech recognition with high accuracy of 99.07% and monitoring of diverse human physiological activities are successfully demonstrated. These proposed unique electrochemical mechanical sensors based on the ubiquitous metallic corrosion phenomena provide a simple but effective approach for the burgeoning human-machine interfacing requirements with great benefit to the resource efficiency and sustainability of our society.

Mesophases with chiral structure under constant electric field constrained by parallel plates with soft anchoring boundary conditions

In this work, we present a new approach based on Euler-Lagrange equilibrium equations analysed from the phase space (PS) perspective to investigate states of elastic deformation of Cholesteric Liquid Crystals (N*) confined, which present an intrinsic chiral structure; between parallel plates by imposing soft anchoring boundary conditions (SAC) under a constant electric field-induced perpendicular to the plates. By minimizing the Frank-Oseen (FO) energy density, we obtain a set of equilibrium state integral equations and corresponding boundary conditions. We establish planar conditions on the plates that force the optical axis to align with a specific direction at the plates. We verify the convergence between SAC to strong anchoring conditions (SSC) whether the ratio between surface and bulk energy tends to infinity, under this condition we examine the different configurations of N* by variating the parameters of control, including a variation of potential difference. We also give a detailed derivation of the threshold electric field value, we show that above this value, there is a transition from N to N*, and below this value transition, N* to focal conic texture is observed. We discuss our results and address our conclusions.

PERUBAHAN KUAT GESER TANAH LEMPUNG TANON PADA METODE ELEKTROOSMOSIS DENGAN VARIASI BEDA POTENSIAL

<p><em>Soft clay soil located in</em> Kalikobok<em> village, </em>Tanon, Sragen<em> is one of soil type that does not qualify to build a structural building on it, because the characters of soft clay soil that has height of water content which is causing the soil carrying capacity becomes low. In other way, if the water content is low, then it will increase the carrying capacity of the soil. Dewatering process is needed, one of the examples is by electroosmosis methods. Electroosmosis is a drainage method by force that drain the water from anode to cathode so it will fix the technical properties of soil. In this study the variables used are the length of time of the electric current and the voltage. The variation of duration is three days and five days, the variation of potential difference that used is 0 volts, 4.5 volts, 9 volts, and 12 volts. The parameters that tested as a comparison are soil shear strength of soil at each voltage and position (anode, middle, cathode). The results showed that the greater application of potential differences can increase the values of c and </em><em>φ, but the value of c at the cathode position decrease due to water accumulation at the cathode. </em></p>

Potential profile near the virtual cathode in presence of charged dust

In this work, concept of virtual cathode and its existence in dusty plasma has been studied by theoretical and numerical analysis. Using basic equations of charge dust, ions, and electrons, the non‐monotonic behaviour of the potential in presence of charged dust has been calculated and plotted as a function of dust density. It has been found that there is a change in potential between cathode and sheath potential and subsequently changes the threshold wall temperature as compared to that of without dust conditions. The threshold wall temperature has been increased due to the ability of micro‐particles acquiring electron charge and hence, reducing potential at the wall. Further, for different values of α (depends on dust density); threshold temperature remained the same for observed virtual cathode. Hence, behaviour of potential has been plotted as a function of α with increasing wall temperatures for two dust charge values (1 and 1,000). Considering no dust charge, it has been observed that, at lower dust density, double layer like structure is formed near the emissive wall. But this double layer structure gets diminishes with increasing dust density. Hence, below a threshold dust density, virtual cathode near to the emissive wall is not possible. While for Zd = 1,000, the formation of virtual cathode appeared even at very small dust density. However, irrespective of variation of potential difference near the wall and existence of virtual cathode at different emission regime the threshold wall temperature remains same. Effect of dust potential dependency on threshold wall temperature has also been discussed in this study.

Use of Cytochrome P450 Enzyme Isolated From <italic>Bacillus Stratosphericus sp.</italic> as Recognition Element in Designing Schottky-Based ISFET Biosensor for Hydrocarbon Detection

Cytochrome P450 enzyme isolated from an extremophile Bacillus Stratosphericus sp. was used as the recognition element for an ion-sensitive field effect transistor (ISFET)-based biosensor. The fabricated ISFET is Schottky-based and has silicon dioxide as a sensing layer. The cytochrome P450 component in its present purified form (pH-7.2) in 5% agarose was laid over the SiO2 gate to examine its capability of generating electronic response in the presence of n-hexadecane and reduced nicotinamide adenine dinucleotide phosphate. The partially purified preparation was obtained from the lysozyme treated spheroplast via ion exchange chromatography followed by the gel filtration chromatography. The variation of potential difference between the gate and the source with respect to pH for the bare ISFET and the variation of gate and source potential difference with respect to the concentration of the measurand at constant current have been recorded for analyses. The observed correlation showed good repeatability of the sensor output suggesting a potential functional sensing device for hydrocarbon detection. The sensitivity parameters for the device have been determined to be 50.65 mV/pH and 54.34 mV/molar for the bare ISFET and enzyme field-effect transistor, respectively.

Noncontact optogalvanic signal detection in DC discharge CO2 lasers

A new noncontact method for detecting optogalvanic signals in DC discharge CO2 lasers is reported. The presented technique is based on the detection of potential difference variations through a capacitor comprised of a discharge plasma column and a coaxial or parallel conductor. The obtained optogalvanic signals exhibit better responsivity and pulse shape in comparison with other conventional techniques; in addition, they are detectable as far as 3 m from a signal source.

Percolation Model for Proton Immobility in Ice

A simple Ising model and a statistical theory of gel formation in a polymer matrix were combined to explain the effect of temperature on the mobility of protons in ice. Cowin et al observed that protons in ice bulk were immobile at temperatures below 190 K, and suddenly become mobile at temperatures above 190 K (Nature 398, 405 (1999)). We proposed here that the transport of protons is controlled by a percolation mechanism. The proton transport is facilitated by the occurrence of easily reoriented water molecules in the ice bulk. The fraction of this molecule depends on temperature and was calculated using a simple Ising model. The formation of network of these molecules which provides pathways for proton transport was calculated using a statistical theory of gel formation in a polymeric system. Our model succeeded to reproduce the variation of potential difference between the ice film surfaces with respect to temperature as observed by Cowin et al based on a soft landing experiment.

風速と地電位差変動の関係

風速と地電位差変動の関係

A study of hydrogen detection with palladium modified porous silicon

A palladium/porous silicon hydrogen sensor has been developed using for the first time the measurement of contact potential difference variations (CPD). The CPD amplitude and speed of response is shown to depend on the type of silicon substrate, the etching current density used for porous silicon preparation and subsequent oxidation. The temporal response features are compared with a Pd/silicon structure and are discussed in terms of a kinetic equation for adsorbtion–desorbtion reactions. The improvement of CPD response in Pd/porous silicon sensor can be explained by a more developed surface under the Pd coating, by a porous silicon surface covered by hydride species or by creation of a thicker Schottky layer in comparison with Pd/Si contacts.

Electrodeposition of Copper under Microgravity Conditions

Copper was electrodeposited from 0.9 M aqueous solution for 8 s during a free‐fall experiment in a drop shaft. A horizontally oriented quasi two‐dimensional electrolytic cell, in which a 200 μm thick electrolyte layer was sandwiched between two sheets of slide glass, fell in the shaft. Electrolysis was conducted at constant current densities from 0.05 to , and the potential difference between electrodes was simultaneously monitored. A common‐path microscopic interferometer was installed in the capsule. The time variation of interference fringe pattern, corresponding to the concentration profile due to the ionic mass‐transfer rate accompanied with copper electrodeposition, was measured in situ around the periphery of a 1 mm diam circular cathode. The morphology of copper electrodeposited under microgravity conditions was compared with that obtained in a ground level experiment. The development of diffusion layer thickness measured by the interferometer increased with the square root of time during the 8 s experiment. The transient diffusion model combined with the migration effect reasonably explained the development of diffusion layer thickness. Calculated surface concentrations corresponded with the measured time variation of potential difference between electrodes. Under the gravitational field, the radius of annual interference fringe pattern developed at a rate much faster than that under microgravity, beginning 1 or 3 s after initiation of electrodeposition. Natural convection was evident in the ground level experiment, even using such a shallow electrolyte layer. Under microgravity, lower index planes preferentially grew to form a smaller number of larger grains, even though electrodeposition was conducted at only for 8 s.

Observation and qualitative modelling of some electrotelluric earthquake precursors

The appearance of strong periodic anomalies, with a period of 24 h, in the electrotelluric field before two large imminent earthquakes is discussed. The precursor occurs as a periodic component superimposed on the large variation of potential difference which starts a couple of days before the earthquake. An attempt is made to find an appropriate geophysical model for the anomaly. It is suggested that changes in electromagnetic induction may take place, as a result of resistivity changes in the earthquake fault area. We account also for possible anisotropy effects of the resistivity response to a stress system. Anisotropy effects related to the T-axis of the fault-plane solution are expected, as resistivity changes are related to opening and closing of cracks and to water transport between cracks. These phenomena are highly sensitive to stress orientation. Consequently, any model of resistivity variations can be modified according to anisotropy of a cracked medium. Thus, we consider sectors of dilatancy and compression; dilatancy in dry or partly saturated rocks leads to a gradual resistivity increase which is followed by a sharp decrease (Fig. 1). This decrease is due to a percolation threshold which can be related to formation of a fracture plane. In saturated rocks the situation may be apparently different. In that case we can expect water to be squeezed out from a sector of compression, and the resistivity of a rock complex would consequently also change before an earthquake. Resistivity anisotropy effects are also expected and are related to the P-axis direction. Thus, changes in the electromagnetic induction are related to the orientation of the fault plane, and corresponding changes (anomalies) in the telluric field have preferred geometrical directions. The apparent resistivity response to resistivity changes in a narrow fault zone demonstrates local extreme values along the zone (Fig. 2). Extreme changes in the electromagnetic induction (and hence in the telluric field) are strongly dependent upon the location of the recording site (compare, for instance, the situation at recording sites A and B in Fig. 2).

Two experiments to measure the electric field at the Earth's surface and the variation of potential difference with height

The Earth is always, somewhere, being struck by lightning flashes, so that it is usually both negatively charged and surrounded by an electric field directed downwards. With increasing height, therefore, the potentials become less negative, i.e., more positive with respect to the Earth's surface. McKenzie (1956) gives a short account of this electric field and its variation and Schonland (1950) and Feynmann et al. (1974) give descriptions of lightning and its causes. There is no 'correct value' for the Earth's electric field at its surface, but the first experiment described measures the field strength at a particular moment to an accuracy with a level of error of less than 2% (this estimate is based on the results of the first preliminary experiment using known artificial fields). The second experiment, which can be set up to give continuous readings of potentials in the field, is much less accurate (error of perhaps 10%) but it does give a good picture of the diurnal variation.

Chemical reactions and oscillating potential difference variations at an oil-water interface

Oscillatory potential difference and interfacial tension variation can be observed at an oil-water interface containing charged species when the conditions are such that hydrodynamic instabilities can occur. We propose a mechanism based on an experimental study accountable for the relaxation-type oscillations observed. It involves the coupling of a chemical reaction occurring in the bulk in the vicinity of the interface with an interfacial transfer by diffusion and adsorption-desorption processes.

529—Chemical reactions and oscillating potential difference variations at an oil-water interface

Oscillatory potential and difference interfacial tension variation can be observed at an oil-water interface containing charge species when the conditions are such that hydrodynamic instabilities can occur. We propose a mechanism based on an experimental study accountable for the relaxation-type oscillations observed. It involves the coupling of a chemical reaction occurring in the bulk in the vicinity of the interface with an interfacial transfer by diffusion and adsorption-desorption processes.

Mrs. Ayrton's Work on the Electric Arc

WHEN a negro servant lighted a fire with Prof. Ayrton's paper on “Variation of Potential Difference of the Electric Arc with Current, Size of Carbons, and Distance Apart”, at Chicago in 1893, he little knew that he was rendering a service to science and to electrical engineering. The paper, the result of three years' work, had not been read in full at the Electrical Congress, and no rough copy, or even an abstract, remained. The research had not been conclusive, and had not been finished when Prof. Ayrton left for America, and was continued under the superintendence of Mrs. Ayrton, who sent him results twice a week by post. Prof. Ayrton had no inclination to rewrite the paper, and Mrs. Ayrton took up the research and published some of the results in the Electrician in 1895, and her book in 1902.