Finger Contact Research Articles

Thermal Field Simulation and Analysis of Tulip Contact Based on Virtual Material Method

In order to analyze the temperature distribution of circuit breaker tulip contact, a thermal field simulation model for tulip contact is built combined with the electromagnetic-stress-thermal coupled finite element simulation and virtual material method which models the contact resistance characteristics of tulip contact. The temperature rise characteristic of tulip contacts under rated current conditions and short-circuit conditions is analyzed with the model. Results show that the virtual material method can describe the contraction resistance and additional resistance at the end of the contact finger simultaneously, so as to simulate the partial high temperature of the contact interface. Then, the influence of spring pressure and pressure uniformity on the thermal field of tulip contact is analyzed. Results show that the decrease of spring pressure and the imbalance of contact finger pressure may lead to an increase in the temperature rise of the tulip contact. The proposed method can be used as a reference for the design and the overheating analysis of tulip contact.

Enhanced Catalytic Palladium Embedded Inside Porous Silicon for Improved Hydrogen Gas Sensing

In this work, we reported on room temperature porous silicon (PS) and embedding PS using simple and economical techniques of electrochemical etching and thermal evaporation. The PS substrate was prepared using the technique of electrochemically etching the n-type Si (100) wafer at a constant current density of 10 mA/cm2 for 10 min under the illumination of incandescent white light. After PS formation, Ge pieces were thermally evaporated onto the two PS substrates in a vacuum condition. This was then followed by the deposition of the ZnO layer onto the Ge/PS substrate by the same method using commercial 99.9% pure ZnO powders. The three samples were identified as PS, Ge/PS and ZnO/Ge/PS samples, respectively. Pd finger contacts were deposited on the PS and embedding PS (Ge/PS and ZnO/Ge/PS) to form Pd on PS hydrogen sensors using RF magnetron sputtering. SEM and EDX suggested the presence of substantial Ge and ZnO inside the uniform circular pores for Ge/PS and ZnO/Ge/PS samples, respectively. Raman spectra showed that good crystalline Ge and ZnO nanostructures embedded inside the pores were obtained. For hydrogen sensing, Pd on ZnO/Ge/PS Schottky diode exhibited a dramatic change of current after exposure to H2 as compared to PS and Ge/PS devices. It is observed that the sensitivity increased exponentially with the hydrogen flow rate for all the sensors. The ZnO/Ge/PS showed more sensitivity towards H2 than that of PS and Ge/PS especially at high flow rate of H2 with higher current gain (69.11) and shorter response (180 s) and recovery times (30 s).

Minding the matrix: The importance of inoculum suspensions on finger transfer efficiency of virus.

The aim of this study was to determine how the transfer efficiency of MS-2 coliphage from the toilet seat to hands and fingertip to lip differs according to the suspension of the inoculum. Hands were sampled after lifting a toilet seat which was inoculated with MS-2 on the underneath side. MS-2 was suspended in a spectrum of proteinaceous and non-proteinaceous solutions. Transfer efficiencies were greatest with the ASTM tripartite soil load (3.02% ± 4.03) and lowest with phosphate-buffered saline (PBS) (1.10% ± 0.81) for hand-to-toilet seat contacts. Finger-to-lip transfer rates were significantly different (p< 0.05) depending on suspension matrix, with PBS yielding the highest transfer (52.53% ± 4.48%) and tryptose soy broth (TSB) the lowest (23.15% ± 24.27%). Quantitative microbial risk assessment was used to estimate the probability of infection from adenovirus and norovirus from finger contact with a toilet seat. The greatest transfer as well as the largest variation of transfer were measured for finger-to-lip contacts as opposed to toilet seat-to-finger contacts. These factors influence the estimation of the probability of infection from micro-activity, that is, toilet seat adjustment. Viruses may be transferred from various human excreta with differing transfer efficiencies, depending on the protein content.

FlexTrail Printing as Direct Metallization with Low Silver Consumption for Silicon Heterojunction Solar Cells: Evaluation of Solar Cell and Module Performance

FlexTrail printing has been invented and developed for (fine‐line) printing of various fluids, e.g., particle‐based metal‐containing fluids, etchants, and liquid‐phase pyrophoric media. Compared to other printing techniques, FlexTrail is highly independent of the fluids’ viscosity. Using this printing approach, feature sizes of 10 μm and below are reached. This work utilizes FlexTrail as a direct metallization method for printing of silver‐nanoparticle‐based front electrodes on busbarless silicon heterojunction (SHJ) solar cells. Thereby, only (9.4 ± 0.9) mg of silver is consumed for printing of a busbarless front grid, which exhibits 80 contact fingers of 156 mm in length. This means a silver reduction of more than 60% compared to screen printing. Solar cells with M2+ wafer size and FlexTrail‐printed front grids reach conversion efficiencies of up to (22.87 ± 0.01)%, which is similar to screen‐printed reference cells. To further demonstrate the practicability of FlexTrail metallization beyond cell level, a FlexTrail‐printed SHJ cell is further processed into a 200 mm × 200 mm‐sized one‐cell module applying SmartWire Connection Technology for interconnection. This module exhibits a maximum power of (5.0 ± 0.1) W, underlining the great potential of FlexTrail printing for the metallization of high‐power SHJ devices with significant silver reduction.

Assessment of the finger contact surface to promote the spin motion in finger follower mechanisms

This work describes the kinematic properties of finger-follower mechanisms in the spatial domain in relation to the spin motion of the follower. In this framework, the effectiveness of the cylinder-on-sphere coupling as contact condition between finger and follower is assessed in relation to the classical cone-on-sphere coupling, showing the capability of the former to achieve a satisfactory valve spin pivoting radius. An analytical study is performed by taking advantage of a geometrical approach which allows to evaluate 3D layouts, demonstrating that the cylinder-on-sphere coupling requires a higher number of design parameters to fully determine the mechanism. This characteristic increases the complexity of the system, but it adds freedom and flexibility to the design procedure. Several design configurations are evaluated to highlight this aspect thanks to a dedicated parametric study, where the declivity of the contact surface is shown to represent the key parameter controlling the spin pivoting radius. In this context, the possibility to control the cylinder surface declivity on multiple planes may be adopted to improve the stability of the mechanism behavior with respect to the production tolerances.

ANALISIS HOTSPOT PADA PMS GARDU INDUK 150 KV RAWADENOK DEPOK MENGGUNAKAN METODE THERMOVISION

Abstract&#x0D; &#x0D; Hotspot analysis at PMS Substation 150 kV Rawadenok Depok using the thermovision method was initiated based on hotspot events on Contact Finger phase S and Disconnecting Switch phase S. This analysis uses the Thermovisi Flir 400 tool as a means of checking high current temperatures that occur in Contact Finger phase S and Disconnecting Switches. The function of this thermovision is to measure the value of the ratio of the energy radiated by an object to the energy radiated by a black body at the same temperature and wave. Then measure the accuracy of Thermovisi starting from the value when checking, testing emissivity values, precision test values, accuracy values and repairs at hotspot points. From the results of the calculation of thermovision accuracy at Bay Cimanggis 1 &amp; 2, it can be concluded that the temperature of the clamps and conductors shows that the conditions are still good. Where the RSM value of 27 samples is 0.4751, and has a coefficient variation (CV) of 0.1% and is categorized as good with a reference of no more than 2%, and has an accuracy value of 97.51%. Prior to the improvement of the hotspot points on Contact Finger it reached 115 oC and the DS Line S phase reached 103 oC after the temperature improvement returned to normal with Contact Finger reaching 36&#x0D; oC and the DS Line S phase reaching 31.2 oC.&#x0D; &#x0D; Keywords : PMS, Thermovisi, Hotspot, Emisivitas

ANALISIS HOTSPOT PADA PMS GARDU INDUK 150 KV RAWADENOK DEPOK MENGGUNAKAN METODE THERMOVISION

Abstract&#x0D; &#x0D; Hotspot analysis at PMS Substation 150 kV Rawadenok Depok using the thermovision method was initiated based on hotspot events on Contact Finger phase S and Disconnecting Switch phase S. This analysis uses the Thermovisi Flir 400 tool as a means of checking high current temperatures that occur in Contact Finger phase S and Disconnecting Switches. The function of this thermovision is to measure the value of the ratio of the energy radiated by an object to the energy radiated by a black body at the same temperature and wave. Then measure the accuracy of Thermovisi starting from the value when checking, testing emissivity values, precision test values, accuracy values and repairs at hotspot points. From the results of the calculation of thermovision accuracy at Bay Cimanggis 1 &amp; 2, it can be concluded that the temperature of the clamps and conductors shows that the conditions are still good. Where the RSM value of 27 samples is 0.4751, and has a coefficient variation (CV) of 0.1% and is categorized as good with a reference of no more than 2%, and has an accuracy value of 97.51%. Prior to the improvement of the hotspot points on Contact Finger it reached 115 oC and the DS Line S phase reached 103 oC after the temperature improvement returned to normal with Contact Finger reaching 36&#x0D; oC and the DS Line S phase reaching 31.2 oC.&#x0D; &#x0D; Keywords : PMS, Thermovisi, Hotspot, Emisivitas

Ex vivo evaluation of personal protective equipment in hands-on defibrillation

BackgroundDefibrillation guidelines recommend avoiding patient contact during shock delivery. However, hands-on defibrillation (compressions during shock) and manual pressure augmentation (MPA – pushing on the defibrillator pads during shock) may lead to improved clinical outcomes. There are limited data addressing the protection provided by personal protective equipment (PPE) during hands-on defibrillation and MPA. This study investigated the hand-to-hand and hand-to-knee leakage current experienced by a simulated kneeling provider wearing different PPE. MethodsA defibrillator was used in experiments on a pork shoulder, investigating three different hands-on positions: closed fist on defibrillator pads; open palm on pads with inadvertent finger contact (overhang); and open palm on the chest. Evaluated PPE included single and double gloves (nitrile and latex) and rescuer cargo trousers in wet and dry conditions (N = 126 experiments). ResultsMean hand-to-hand leakage currents in MPA without PPE was 0.41 mA (0.2–0.74 mA) and with PPE was 0.2 mA (0.08–0.58 mA). For experiments involving finger or palm contact on the chest, wearing any PPE resulted in a >99% reduction in mean leakage currents from an average 354.58 mA (258.96–446.22 mA) to an average 0.48 mA (0.16–1.56 mA). Rescuer trousers were insulative in dry conditions even without gloves (0.2–1.2 mA). ConclusionThis study demonstrated that the tested clinical examination gloves markedly reduced leakage current to the rescuer and that the lowest levels of leakage current occurred during MPA attributed to the electrical insulation of the pads.

Progress with screen printed metallization of silicon solar cells - Towards 20 μm line width and 20 mg silver laydown for PERC front side contacts

Within this work, we evaluate and compare different high-end screens for the fine line front side metallization of passivated emitter and rear cell (PERC) solar cells. Three types of high-end screens are considered including (i) a fine mesh screen configuration with a mesh count MC = 520 wires/inch and standard mesh angle of φ = 22.5°, (ii) a knotless screen configuration with a mesh angle of φ = 0° as well as (iii) a knotless screen configuration utilizing a rectangular mesh with different mesh count in warp and weft direction MC = 460/430 wires/inch. Using these advanced screen configurations, all PERC solar cells are metallized with a busbarless fine line front side grid at a nominal contact finger opening of 20 μm and 24 μm. All screen configurations obtained excellent results regarding finger geometry, silver laydown and electrical performance of the front side grid and the fabricated PERC solar cells. The most efficient group obtained a printed mean finger width of 21 μm with a silver laydown of only 19 mg and revealed a mean energy conversion efficiency of 22.7%. Furthermore, we investigate the geometric and electric results of the printed front side contacts in detail using advanced image analysis software and scanning electron microscopy and discuss the impact of the fine line front side metallization on the applicable cell interconnection concepts depending on the series resistance losses. • Evaluation of different high-precision screen configurations for fine line metallization of PERC solar cells. • Reduction of silver laydown to less than 20 mg on the front side while maintaining excellent I–V-results of the solar cells. • In-depth analysis of the geometric properties and electric results of the printed fine line front side contacts. • Discussion of the impact of different screen configurations on various aspects of solar cells.

Analysis of thermocouple-based finger contact temperature measurements

The understanding of heat conduction during finger contact with cooler or hotter objects is important for designing many electronic devices and for setting safety standards in a variety of occupational settings. In the most common experimental approach to study this process, a micro-thermocouple is placed at the finger-object interface. However, the interpretation of what this measurement corresponds to is not clear. To this end, we develop a three-dimensional thermal simulation of the finger-thermocouple-substrate configuration. The model predictions match finger cooling measurements in eight distinct cases available in prior literature (finger pressed with 1 N or 9.8 N against a steel or an aluminum substrate held at −2 °C or −10 °C). We demonstrate that the thermocouple can be represented accurately as a truncated sphere with emerging cylindrical wires while a multilayer block model of the finger provides similar results to an anatomically representative model. Our simulations show that in the eight previously studied cooling cases, the average surface temperature of skin that is in contact with the substrate follows nearly the same but offset cooling trend as the thermocouple tip temperature. The value of the offset is predominantly determined by the substrate material, with the thermocouple tip temperature being lower than the average skin surface temperature by 1–5 °C and 3–10 °C for steel and aluminum substrate cases, respectively. This temperature difference results in a moderate to an extreme thermocouple underprediction of the time necessary for the skin surface to reach the experimental safety threshold of 1 °C. Consequently, from the perspective of the safety related applications the thermocouple measurement provides a conservative limit on the contact duration and thereby is suitable for such purposes, but for applications requiring accurate skin temperature measurements alternative experimental approaches should be used.

Apparent Randomness of the Normal-Force Dependence of the Coefficient of Friction between a Bare Finger and Artificial Skin under Active Tactile Exploration

When a finger actively slides over a surface, contact conditions including the contact area, sliding speed, and finger moisture naturally fluctuate. These random fluctuations lead to an apparent change of frictional properties and influence tactile pleasantness. Nonetheless, this probabilistic behavior has not been explicitly analyzed in previous studies on human fingertips. This study investigates the dependence of the coefficients of kinetic friction on the normal force produced by sliding a bare finger over different artificial skins with seven levels of hardness. The coefficient of friction was modeled as a power function of the normal force. An experimental study that involved sliding a finger over artificial skin surfaces was carried out under two conditions: the fingertip being wiped by a dry cloth or a cloth soaked in ethanol. Although the exponential term was assumed to be nearly constant for identical tribological conditions, we observed that the exponent varied randomly and could be negative, zero, or positive. This can be attributed to the variation of gross finger deformation that was not controlled during the observation. The probability density function of the exponent depended on the moisture content of the finger and object hardness. The variability of the exponent was higher for a soft material than it was for a harder material. In other words, for the softer materials, the exponent appears more random. Furthermore, the exponent tended to be positive and the coefficient of friction increased with the normal force when the finger was wiped with ethanol. These findings play an important role in understanding the frictional forces produced during skin–skin contact in terms of determining the root cause of random variations in the dependence of the coefficient of friction on the normal force.

Evaluation of multiple perceptual qualities of transcutaneous electrical nerve stimulation for evoked tactile sensation in forearm amputees

Objective. Evoked tactile sensation (ETS) elicited by transcutaneous electrical nerve stimulation (TENS) is promising to convey digit-specific sensory information to amputees naturally and non-invasively. Fitting ETS-based sensory feedback to amputees entails customizing coding of multiple sensory information for each stimulation site. This study was to elucidate the consistency of percepts and qualities by TENS at multiple stimulation sites in amputees retaining ETS. Approach. Five transradial amputees with ETS and fourteen able-bodied subjects participated in this study. Surface electrodes with small size (10 mm in diameter) were adopted to fit the restricted projected finger map on the forearm stump of amputees. Effects of stimulus frequency on sensory types were assessed, and the map of perceptual threshold for each sensation was characterized. Sensitivity for vibration and buzz sensations was measured using distinguishable difference in stimulus pulse width. Rapid assessments for modulation ranges of pulse width at fixed amplitude and frequency were developed for coding sensory information. Buzz sensation was demonstrated for location discrimination relating to prosthetic fingers. Main results. Vibration and buzz sensations were consistently evoked at 20 Hz and 50 Hz as dominant sensation types in all amputees and able-bodied subjects. Perceptual thresholds of different sensations followed a similar strength-duration curve relating stimulus amplitude to pulse width. The averaged distinguishable difference in pulse width was 12.84 ± 7.23 μs for vibration and 15.21 ± 6.47 μs for buzz in able-bodied subjects, and 14.91 ± 10.54 μs for vibration and 11.30 ± 3.42 μs for buzz in amputees. Buzz coding strategy enabled five amputees to discriminate contact of individual fingers with an overall accuracy of 77.85%. Significance. The consistency in perceptual qualities of dominant sensations can be exploited for coding multi-modality sensory feedback. A fast protocol of sensory coding is possible for fitting ETS-based, non-invasive sensory feedback to amputees.

Human In-Hand Motion Recognition Based on Multi-Modal Perception Information Fusion

A human in-hand motion (HIM) recognition system based on multi-modal perception information fusion is proposed in this paper, which can observe the state information between the object and the hand by using customized ten kinds of HIM manipulation in order to recognize the complex HIMs. First, combined with the characteristics of HIM capture, ten kinds of HIM sets are designed, and finger trajectory, contact force and electromyographic signal data are acquired synchronously through the multi-modal data acquisition platform; second, motion segmentation is realized through the threshold segmentation method, the multi-modal signal preprocessing is realized by Empirical Mode Decomposition (EMD), and multi-modal signal feature extraction is realized by Maximum Lyapunov Exponent (MLE); then, a detailed non-linear data analysis is carried out. A detailed analysis and discussion are presented from the results of the Random Forest (RF) recognizing HIMs, the comparison results of motion recognition rates of different subjects, the comparison results of motion recognition rates of different perceptrons, and the comparison results of the motion recognition rates of different machine learning methods. The experimental results show that the multi-modal perception information based HIM recognition system proposed in this paper can effectively recognize ten different HIMs, with an accuracy rate of 93.72%.

Static Characteristics of Finger Seal considering Contact between Fingers and Rotor

Finger seals are a new type of seal with good sealing performance and long service life. The noncontacting feature relies on the gas film force. However, when the seal works in an unsuitable environment or its design parameters are not reasonable, the lifting pad may not be able to generate sufficient air film force. This causes contact between the fingers and the rotor, resulting in a reduced service life of the seal. In view of this situation, this paper proposes a method that can quickly determine whether there is enough gas film force to lift the sealing finger at the design stage. The aeroelastic coupling characteristics of the noncontacting finger seal are studied in conditions where contact exists between the fingers and the rotor. The influences of various environmental and key structural parameters on the number of contact fingers, leakage, bearing force, and friction moment are studied. The results show that the pressure difference, eccentricity, and key design parameters have important effects on the number of contact fingers. The effect of rotation speed is relatively small. This paper provides a time-efficient tool for the design of noncontacting finger seals, which can quickly predict the performance of the sealing system.

Electron-beam lithography of cinnamate polythiophene films: conductive nanorods for electronic applications.

We report the electron-beam induced crosslinking of cinnamate-substituted polythiophene proceeding via excited state [2+2]-cycloaddition. Network formation in thin films is evidenced by infrared spectroscopy and film retention experiments. For the polymer studied herin, the electron-stimulated process appears to be superior to photo (UV)-induced crosslinking as it leads to less degradation. Electron beam lithography (EBL) patterns cinnamate-substituted polythiophene thin films on the nanoscale with a resolution of around 100 nm. As a proof of concept, we fabricated nanoscale organic transistors using doped and cross-linked P3ZT as contact fingers in thin film transistors.

A methodology to evaluate contact areas and indentations of human fingertips based on 3D techniques for haptic purposes

This paper presents a methodology to study the contact of human fingers with surfaces based on 3D techniques. This method helps to investigate the fingertip mechanical properties which are crucial for designing haptic interfaces. The dependence of the fingertip deformation on the applied forces is obtained both with theoretical and experimental approaches. The experimental procedure is based on digital measurements by 3D optical scanners to reconstruct the geometry of the fingertip impression and on force measurements by an instrumented plate. Results highlight the force-displacement trend and can be validated with a Finite Element Model (FEM), with data from literature or with measurements at a force-strain gauge. Gross contact areas, radii and work of adhesion are also detected, and results are compared with contact models available in literature.• A sensorized plate with a thin force sensitive resistor and a dough material layer is used to measure the contact force corresponding to a specific digital imprint.• 3D indentation maps are obtained and evaluated by comparing the 3D scan model of fingertips during imprinting with the digital model of the undeformed fingers and of the imprints.• Force-displacement results can be validated by comparison with a developed FEM, a force-displacement gauge or literature outcomes.

Tactile Texture Rendering for Electrostatic Friction Displays: Incorporation of Low-Frequency Friction Model and High-Frequency Textural Model.

Tactile texture presentation on touch panels enhances their usability and realizes immersive user interfaces. This study develops a tactile texture rendering method for electrostatic friction displays. The method combines two rendering models for material textures compared with previous studies which focused on either of these two models. One of these models is a physical model that simulates low-frequency frictional signals depending on the exploratory finger velocities and contact loads. The other is an autoregression-based data-driven model for high-frequency textural friction. For user studies, we compared combining the two models with using only the physical model for the four types of materials. Although the effectiveness varied across the materials, the subjectively judged realism and identification of the materials were improved for the combined condition. The new method combining high-frequency textural information and low-frequency physical model-based friction is expected to provide realistic tactile textures for electrostatic surface tactile displays.

Finger Contact Area Analysis with Convolutional Neural Networks

ABSTRACT The detection of the contact area formed between a human finger and a counter surface is of great interest because it is the key parameter for various interaction parameters. Adhesional friction forces and the thermal contact conductance critically depend on the contact area, further influencing the tactile sensation of stickiness and warmth. The contact area is also of concern regarding safety issues. Injuries caused by objects slipping out of our hands might be prevented by optimizing the contact area and the concomitant grip through appropriate surface structures and material choice. Until now the contact area is mainly studied on smooth and transparent materials. The contact area is recorded optically and rule-based image processing methods can be used for detection. These methods might be insufficient for rough surfaces where the contact area is optically unclear due to light scattering. In this paper we demonstrate the successful analysis of such optically unclear contact area images via convolutional neural networks to identify the fingerprint ridges in contact with structured surfaces. The proposed method relies on the generation of synthetic contact images that provide the pixelwise ground truth for the efficient training of a segmentation pipeline based on convolutional neural networks.

Electroplated Copper Metal Contacts on Perovskite Solar Cells

Electroplated copper contacts on small‐area single‐junction perovskite solar cells (PSCs) using an atomic layer deposited (ALD) Al2O3 masking layer on ITO are demonstrated for the first time. The photoconversion efficiency of ≈11% after manufacturing the Cu contacts confirms that PSCs can survive the wet‐chemical plating process. From the successful realization of plated contact fingers, the creation of an electrical contact between the Cu electrode and the ITO on the FA0.75Cs0.25Pb(I0.8Br0.2)3 perovskite absorber is inferred. Furthermore, scanning electron microscopy (SEM) with energy‐dispersive X‐ray (EDX) analysis shows the formation of a compact interface between ITO and plated Cu. An additional plating approach, using self‐passivated aluminum as mask, allows to produce well‐defined 30 μm wide Cu contacts on the PSC. Such a plating process allows for plating a low‐resistive Cu grid simultaneously on both sides of a perovskite silicon heterojunction tandem solar cell with TCO, independent of substrate size.

A passive perspiration biofuel cell: High energy return on investment

<h2>Summary</h2> Self-powered wearable systems that rely on bioenergy harvesters commonly require excessive energy inputs from the human body and are highly inefficient when accounting for the overall energy expenses. A harvester independent from the external environment for sedentary states has yet to be developed. Herein, we present a touch-based lactate biofuel cell that leverages the high passive perspiration rate of fingertips for bioenergy harvesting. Powered by finger contact, such a bioenergy-harvesting process can continuously collect hundreds of mJ of energy during sleep without movements, representing the most efficient approach compared to any reported on-body harvesters. To maximize the energy harvesting, complementary piezoelectric generators were integrated under the biofuel cell to further scavenge mechanical energy from the finger presses. The harvesters can rapidly and efficiently power sensors and electrochromic displays to enable independent self-powered sensing. The passive perspiration-based harvester establishes a practical example of remarkably high energy return on investment for future self-sustainable electronic systems.