Application Of Electrostatic Force Research Articles

Characterization and optimization of the mechanical properties of electrospun gelatin nanofibrous scaffolds

Purpose Electrospinning is a versatile technique for producing polymeric nanofibers by the application of electrostatic forces. The electrospinnability of polymeric solutions and the properties of electrospun nanofibers can be influenced and tuned by the process parameters. This paper aims to investigatethe influence of three key process parameters on the tensile strength of electrospun gelatin nanofibrous scaffold. Design/methodology/approach The experiments were conducted with a custom-built electrospinning system. Design of experiments of the three operating variables, namely, gelatin concentration, applied potential and feed rate, with five levels were investigated. Optimization of the tensile strength of electrospun gelatin scaffold was achieved with the aid of response surface methodology. Findings The resulting second-order mathematical models capable of demonstrating good correlation on the effects of the three identified process parameters with the experimental measured tensile strength, where the highest tensile strength was obtained on gelatin nanofibrous scaffold electrospun at 16per cent (w/v) gelatin concentration in acetic acid, 19 kV applied potential and 0.31 ml/h feed rate. Originality/value The resulting second-order mathematical models capable of demonstrating good correlation on the effects of the three identified process parameters with the experimental measured tensile strength, where the highest tensile strength was obtained on gelatin nanofibrous scaffold electrospun at 16per cent (w/v) gelatin concentration in acetic acid, 19 kV applied potential and 0.31 ml/h feed rate.

Application of Electrostatic Force on Moon, Mars and Asteroids

Because mitigation, sampling, and utilization technologies of regolith are critically important for lunar, Mars, and asteroid explorations, we are conducting the following research and development; (1) electrostatic cleaning of dust on optical elements, (2) electrostatic and magnetic cleaners for dust adhering to spacesuits, (3) electrostatic shield for dust entering into mechanical seals of equipment, (4) transport of regolith based on electrostatic traveling-wave and me-chanical vibration, (5) electrostatic particle-size classification, (6) electrostatic and magnetic sampling of regolith, (7) electrostatic precipitation in the Martian environment, and (8) electrostatic manipulation of a small particle.

A Study on the Electrostatic Precipitation Using Electric Charged Carbon Filter

Air purifiers generally have used air filter, but the long time operation of the air purifier causes deterioration of the dust collecting efficiency of the air filter. Application of electrostatic force can be one of the effective method for this case. In this study, two conductive carbon filters have a function as dust collecting electrode. The two carbon filters charged with HVDC are installed across the air duct in fairs. And the dust collection and power consumption characteristics of the proposed electric precipitator are investigated experimentally. As the applied voltage was increased, the dust collection efficiency was improved. The dust collection efficiency of about 98.9% was obtained at the case 28kV applied, in this experiment. It is possible to improve the dust collection efficiency by simply applying DC voltage without power consumption.

Fundamental Study on Setting of Diamond Abrasive Grains Using Electrostatic Force for Single-Layered Metal Bond Wheel

Single-layered metal bond diamond wheels are useful to high efficient grinding of difficult-to-grind materials because of the high gripping force of abrasive grains and the controllable grain density. In this paper, fundamental information are obtained for an application of electrostatic force to setting of diamond grains into pasted metal bond slurry layer on wheel surface, investigating experimentally jumping phenomenon of diamond grains in an electrostatic field between a electrode plate and metal bond slurry layer. The SD grains and the SDC grains coated with Ti are selected. SDC grains jump into a metal bond layer as quick as making an electrostatic field, however SD grains jump with short time lags. The setting rate of SDC grains is larger than that of SD grains, and setting position accuracy of SDC grain array is better than SD grain array. The possibility of setting abrasive grains into single-layered metal bond diamond wheel surface using electrostatic force is obtained and SDC grains are suitable to the proposed abrasive setting method.

A Digital Microfluidic Method for in Situ Formation of Porous Polymer Monoliths with Application to Solid-Phase Extraction

We introduce the marriage of two technologies: digital microfluidics (DMF), a technique in which droplets are manipulated by application of electrostatic forces on an array of electrodes coated by an insulator, and porous polymer monoliths (PPMs), a class of materials that is popular for use for solid-phase extraction and chromatography. In this work, circular PPM discs were formed in situ by dispensing and manipulating droplets of monomer solutions to designated spots on a DMF device followed by UV-initiated polymerization. We used PPM discs formed in this manner to develop a digital microfluidic solid-phase extraction (DMF-SPE) method, in which PPM discs are activated and equilibrated, samples are loaded, PPM discs are washed, and the samples are eluted, all using microliter droplets of samples and reagents. The new method has extraction efficiency (93%) comparable to that of pipet-based ZipTips and is compatible with preparative sample extraction and recovery for on-chip desalting, removal of surfactants, and preconcentration. We anticipate that DMF-SPE may be useful for a wide range of applications requiring preparative sample cleanup and concentration.

Electrostatic forces in fibrous filters—a review

Among various devices for removing submicrometer particles from a gas stream, fibrous filters have the advantages of providing high collection efficiencies at low-pressure drop. Even in the absence of electrostatic forces, a fibrous filter captures particles efficiently by inertial impaction, interception, and convective Brownian diffusion. Application of electrostatic forces can significantly increase the efficiency of collection. The process of aerosol filtration in the presence of electrostatic forces is complicated. Although past studies have led to a good understanding of the filtration process in clean filters, there is a marked gap between theory and experiment of the change in collection efficiency with particle loading in a filter in the presence of electrostatic forces. This paper gives a review on both theoretical and experimental studies on the application of electrostatic forces in filtration and discusses the needs for further studies on the effect of particle loading.

The polarity of streaming current in water passing through a pyrophylite disc

Pyrophylite is a porous material composed of the same constituent substances as bentonite, which is widely employed as a shield against high-level radiation leakage. However, as these materials allow a seepage of water, special attention is required when they are actually used for this purpose. One method that has been considered for preventing water seepage is the application of electrostatic force [1]. As a preparatory step of research, the authors have conducted experiments into the properties of the streaming current generated by the passage of water through the material. All air was extracted from the material by means of a vacuum pump, and the streaming current was measured. It was found to be positive. However, a repetition of the same experiment without the extraction of air yielded a negative polarity. The ζ potential of pyrophylite particles is −25 mV [2]. In general, streaming current usually displays the same polarity as ζ potential. From this point of view, the phenomenon of polarity change appearing when the air is extracted seems difficult to account for. In the discussion part of this paper, an attempt is made to explain the phenomenon using SEM photographs and the Poisson-Boltzmann equation.

Design of novel thin-film piezoelectric accelerometer

A novel piezoelectric thin-film accelerometer has been designed and its performance has been analysed. The piezoelectric thin film (PZT for example) is delineated into an array of pads to reduce the sensor capacitance. By filling the cavity around the PZT pads either with a polymer or a gas with controlled pressure, damping can be controlled. The piezoelectric thin-film material (i.e., pads) is clamped between a seismic mass and a base plate (silicon substrate). During acceleration in the axial direction the seismic mass exerts a force on the piezoelectric layer, resulting in the generation of a charge due to the piezoelectric effect. The induced charge is independent of the dimensions of the piezoelectric layer and hence of its tolerances.The generated charge is directly sensed by a charge-sensitive preamplifier that is implemented by CMOS technology on a tiny silicon chip. In principle, the proposed thin-film accelerometer can be integrated with the electronic readout and can be extended into an array of accelerometers. The dynamic response is presented and the trade-offs between several design considerations are discussed. For a specific design, a sensor sensitivity of 320 mV g −1 and lower and upper cut-off frequencies of, respectively, 1 Hz and compensation for temperature and pyroelectric effects. In addition, self-test features based on the application of electrostatic forces are feasible but require more sophisticated signal processing.