Finger Contact Research Articles

A thermal insulation microactuator for Braille display using paraffin wax/carbon nanotube composite with induction heating

A new thermal insulation microactuator for Braille display using a phase change material (PCM) composite with induction heating is proposed. The PCM composite is prepared by fully mixing paraffin with multi-walled carbon nanotubes (MWCNTs), which is mainly used as both electrically and thermally conductive enhancer. As a result of that, the PCM composite is conductive and a wireless induction heating can be realized with the paraffin composite, which avoids the connection of wires from the inner chamber with a relatively simple fabrication process. In order to prevent the penetration of the paraffin from the elastic film, a solvent-resistant TPU diaphragm is adopted to seal the PCM chamber. In addition, thermal insulation between the higher temperature of PCM and the finger contact is designed by adding the PDMS diaphragm with PDMS pins. When the input power is 1.29[Formula: see text]W at AC frequency of 1[Formula: see text]kHz, the actuation height of the Braille dot reaches 259[Formula: see text][Formula: see text]m within 7[Formula: see text]s. The microactuator for Braille display presented in this paper has the advantages of short response time, thermal isolation, simple fabrication, small size and low cost.

A Multifunctional MXene/PVA Hydrogel as a Continuous Ionic Thermoelectric Generator and a Strain/Temperature Sensor.

This research reports a continuous output ionic thermoelectric (i-TE) system based on MXene/PVA (polyvinyl alcohol) hydrogel, by utilizing thermo-diffusion of Cu2+ and Cl- ions and the redox reaction involving Cu/Cu2+ at the electrode interfaces. The thermopower of the i-TE system can be independently tuned to a value of -3.13 mVK-1 by adjusting the ion diffusivity via MXene (Ti3C2Tx). The i-TE system demonstrates a rapid response time of less than 100 s, outperforming any other polyelectrolyte-based system. Crucially, the i-TE system achieves continuous current output when equipped with copper electrodes, facilitated by the redox reaction involving Cu/Cu2+, and maintains stable long-term outputs across a range of resistances from 1 kΩ to 1 MΩ. A three-serial-connected i-TE module demonstrates an output voltage of 26 mV with 6 °C temperature difference, confirming the feasibility of creating an array of i-TE devices for substantial energy output. Beyond energy harvesting, the MXene/PVA hydrogel serves as multifunctional strain/temperature sensors, capable of detecting mechanical strains via the piezoresistive effect and locating finger contact points via the ionic thermoelectric effect.

Correlation Between Broken Contact Fingers and I–V Characteristics of Partially Shaded Photovoltaic Modules

This paper reports on the correlation between broken contact fingers and the shape of the current–voltage (I–V) curve of a photovoltaic (PV) module. It was found that the broken contact fingers of a solar cell in the PV module cause a noticeable change in the I–V curve of the PV module when the solar cell was partially shaded. The broken contact fingers were inspected by microscopic imaging and electroluminescence (EL) imaging, and a further investigation was carried out using a single solar cell. The results show that the fill factor of the cell decreased from 0.75 of full contact to 0.47 after 16 contact fingers were broken, confirming the correlation between the I–V curve shape and broken contact fingers. This result reveals that the shape of the I–V curve of a PV module under individual-cell partial shading may be used as an indicator of broken contact fingers, which offers an alternative approach to EL imaging for detecting broken contact fingers in PV modules in daylight.

Graphene-Infused Sustainable Rubber-Based Triboelectric Nanogenerator For Real-Time Human Motion Monitoring.

Triboelectric nanogenerators (TENG) are promising alternatives for clean energy harvesting. However, the material utilization in the development of TENG relies majorly on polymers derived from non-renewable resources. Therefore, minimizing the carbon footprint associated with such TENG development demands a shift toward usage of sustainable materials. This study pioneers using natural rubber (NR) as a sustainable alternative in TENG development. Infusing graphene in NR, its dielectric constant and tribonegativity are optimized, yielding a remarkable enhancement. The optimized sample exhibits a dielectric constant of 411 (at 103Hz) and a contact potential difference (CPD) value of 1.85V. In contrast, the pristine NR sample showed values of 6 and 3.06V for the dielectric constant and CPD. Simulation and experimental studies fine-tune the TENG's performance, demonstrating excellent agreement between theoretical predictions and practical studies. Sensors developed via stencil printing technique possess a remarkably low layer thickness of 270µm, and boast a power density of 420mWm-2, a staggering 250% increase over conventional NR. Moreover, the material is pressure sensitive, enabling precise real-time human motion detection, including finger contact, finger bending, neck bending, and arm bending. This versatile sensor offers wireless monitoring, empowering healthcare monitoring based on the Internet of Things.

Tactile Perception in Upper Limb Prostheses: Mechanical Characterization, Human Experiments, and Computational Findings.

Tactile feedback is essential for upper-limb prostheses functionality and embodiment, yet its practical implementation presents challenges. Users must adapt to non-physiological signals, increasing cognitive load. However, some prosthetic devices transmit tactile information through socket vibrations, even to untrained individuals. Our experiments validated this observation, demonstrating a user's surprising ability to identify contacted fingers with a purely passive, cosmetic hand. Further experiments with advanced soft articulated hands revealed decreased performance in tactile information relayed by socket vibrations as hand complexity increased. To understand the underlying mechanisms, we conducted numerical and mechanical vibration tests on four prostheses of varying complexity. Additionally, a machine-learning classifier identified the contacted finger based on measured socket signals. Quantitative results confirmed that rigid hands facilitated contact discrimination, achieving 83% accuracy in distinguishing index finger contacts from others. While human discrimination decreased with advanced hands, machine learning surpassed human performance. These findings suggest that rigid prostheses provide natural vibration transmission, potentially reducing the need for tactile feedback devices, which advanced hands may require. Nonetheless, the possibility of machine learning algorithms outperforming human discrimination indicates potential to enhance socket vibrations through active sensing and actuation, bridging the gap in vibration-transmitted tactile discrimination between rigid and advanced hands.

Deep learning-based prediction of 3-dimensional silver contact shapes enabling improved quality control in solar cell metallization

The industrial metallization of Si solar cells predominantly relies on screen printing, with silver as the preferred electrode material. However, the design of commercial screens often leads to suboptimal silver usage and increased electrical resistance due to print-related inhomogeneities like mesh marks, constrictions and spreading. Real-time monitoring of quality parameters during production has thus become increasingly critical. Current inline optical quality control systems usually only include 2D visualizations of the printed layout, which limits their effectiveness in quality control. Options that allow 3D measurements are usually slow, expensive, and therefore not worth considering in most cases. This research focuses on the development of a model that can estimate the three-dimensional shape of printed contact fingers from a single 2D image without the need of additional hardware using deep learning. Furthermore, a workflow for the generation of training data, which involves the creation of image pairs from a 2D microscope and a 3D confocal laser scanning microscope (CLSM) to accurately represent solar cell fingers, is presented. After model training, the predicted height maps are compared with the ground truth height maps, and the robustness of the model with respect to a paste variation and screen parameter variation is examined. The results confirm the feasibility and reliability of deep learning-based 3D shape estimation, extending its applicability to new, previously unseen data from screen-printed contact fingers. With a structural similarity index (SSIM) score of 0.76, a strong correlation between the estimated and ground truth height maps is established. In summary, our deep learning-based approach for height map estimation offers an effective and reliable solution for fast inline detection and analysis of the cross-sectional area of the printed contact fingers.

Analysis of electrical contact characteristics of strap contacts used in high voltage bushings under eccentric conditions

AbstractThe contact finger electrical connection structure is a crucial component of high voltage bushings, and its safety and reliability directly impact the operational stability of the bushing. To investigate electrical contact performance of the contact finger under eccentric conditions, a three‐dimensional electrical, thermal, and force multi‐physics coupling calculation model was established. Additionally, a test platform was constructed to measure electrical contact characteristics of the contact finger. The contact characteristics of the contact finger when the male head was axially deflected and radially offset compared to the female head were obtained. The research findings indicate when the male head deflects axially, the contact force changes of the contact finger blades on both sides are opposite. Moreover, as the axial deflection angle of the male head increases, the resistance of the electrical connection structure shows a rising‐slow decreasing‐fluctuating trend. The resistance is highest at 3°, with a resistance increase rate of 7.35%. Furthermore, the resistance of the electrical connection structure varies with the radial offset of the male head, following a power function. Contact failure occurs when the radial offset is 1.31 mm, and the resistance increase rate reaches 24.9% at a radial offset of 1.58 mm.

Towards a cutting‐edge metallization process for silicon heterojunction solar cells with very low silver laydown

AbstractWithin this work, we investigate the potential to optimize the screen‐printed front side metallization of silicon heterojunction (SHJ) solar cells. Three iterative experiments are conducted to evaluate the impact of the utilized fine mesh screen configurations and grid layout adaption (finger pitch) for the front side metallization on silver laydown and electrical performance of the solar cells. With respect to the screen configuration, we compare the performance of a fine‐mesh knotless screen to a conventionally angled screen demonstrating an additional gain of Δη = +0.1%abs due to reduced shading losses. Additionally, a grid layout is improved by increasing the number of contact fingers from 120 to 156. Furthermore, the current possibility to push the fine‐line printing process for low‐temperature pastes to the limit is investigated by reducing the nominal finger width wn to 20, 18, and 15 μm. It is shown that even the smallest nominal width of wn = 15 μm can be printed with high quality, leading to an additional efficiency gain of Δη = +0.15%abs as well as a reduction of silver paste laydown by −5 mg. Finally, a batch of champion cells is fabricated by applying the findings of the previous experiments, which results in a maximum efficiency of ηmax = 23.2%. Compared to the reference group without optimization, this corresponds to a gain of Δη = +0.17%abs, which comes along with an additional decrease of the silver paste laydown by approximately −2 mg. This emphasizes the significance of consistent optimization of the screen‐printing process in terms of cell performance and resource utilization for SHJ solar cells.

Analysis and Preventive Measures for an Abnormity of 220kV Isolating Switch

With the development of the power grid, the cutter brake is a kind of main equipment used cooperatively in the transmission and distribution line of the substations with the circuit breaker in the operation and maintenance of the electric power system. Its main role is to ensure the safety of the staff during the maintenance of high voltage equipment. The cutter brake forms a clear disconnection point to provide the staff with a sufficiently large insulation interval between the equipment in need of repair and other energized parts. In the long-term operation, various reasons may lead to various failures of the cutter brake, causing great security risks to the safe and stable operation of the power grid and personal safety. This paper is mainly focused on analyzing the abnormal phenomenon of the poor contact of the dynamic and static contact fingers of B phase of I cutter brake of Xinlang Line 1 in the 220kV substation, which causes most of the current to flow through the B phase of Xinlang Line 2. Future management and preventive measures for this type of cutter brake are also proposed in this paper.

A smooth surface measurement method by flexible contact using multiple fingers device

Contact measurement technology is commonly used for analysis and modeling of three-dimensional (3D) object. This paper presents a contact measurement method, using a claw type probe based on a set of rotary encoders that can flexibly contact objects with efficiently multi-lines scanning. In this paper, a 3D measurement system by flexible contact of multiple fingers was built. The claw probe was set on a coordinate measurement machine. By moving the position of the claw for interpolation detection to improve the sampling rate, higher precision 3D reconstruction was achieved. Also, a compensation algorithm was proposed for this type detector to improve measuring accuracy. In the experiments, two surface models were produced by 3D printing as the test objects. By comparing the designed surface with the reconstructed surface, it is demonstrated that this system can effectively and softly measure smooth surface, like the back of human body, which is valuable for further study and use in rehabilitation massage, apparel design, and etc.

Preparation and properties of high molecular weight high temperature resistant carborane polyurethane adhesive

The long-term use temperature of the traditional high-temperature adhesive can only reach about 280 °C, and it cannot be used in extreme environments such as acid and alkali for a long time, which greatly limits its application in aerospace and other fields. Because of its unique three-dimensional structure, carborane has excellent thermal stability and chemical stability. Based on this, first, this article introduced carborane monomer into polyurethane structure, using indirect copolymerization method, Hydroxyl carborane derivative (m8) and conventional polyether diols were used as soft segments. By adjusting the introduction ratio of m8, a series of copolymerized carborane polyurethane (Co-CBR-PU) with controllable thermal and mechanical properties were successfully prepared. Its structure and molecular weight were characterized by FTIR and gel permeation chromatography (GPC), its surface morphology were observed by SEM. The thermal stability and mechanical properties were studied by thermogravimetric test, tensile test and rheological dynamic mechanical analysis test., and its activity, solvent resistance and hydrophobic properties were studied by finger contact method, solvent resistance test and contact Angle test. Second, the high temperature resistant carborane polyurethane adhesive (PUAS) was prepared using Co-CBR-PU as matrix and its adhesion was studied. The results show that a series of Co-CBR-PU has good high temperature resistance, mechanical properties and solvent resistance after adding carborane monomer, and its various properties were optimal when the addition amount of m8 was 15 wt%. The carborane PUAS prepared by using it as the substrate has excellent high temperature adhesion to different adhesive parts. The aim of this study is to reduce the cost of synthesis of carborane polyurethane by regulating the proportion of carborane, and then realize the industrial trial production of high temperature resistant carborane adhesive.

Bradyphrenia and Tachyphrenia in Idiopathic Parkinsonism Appear, in Part, Iatrogenic: An Observational Study with Systematic Review Background.

We question whether bradyphrenia, slowing of cognitive processing not explained by depression or a global cognitive assessment, is a nosological entity in idiopathic parkinsonism (IP). The time taken to break contact of an index finger with a touch-sensitive plate was measured, with and without a warning in the alerting signal as to which side the imperative would indicate, in 77 people diagnosed with IP and in 124 people without an IP diagnosis. The ability to utilise a warning, measured by the difference between loge-transformed reaction times (unwarned minus warned), was termed 'cognitive efficiency'. It was approximately normally distributed. A questionnaire on self- and partner perception of proband's bradyphrenia was applied. A multivariable model showed that those prescribed levodopa were less cognitively efficient (mean -5.2 (CI -9.5, -1.0)% per 300 mg/day, p = 0.02), but those prescribed the anti-muscarinic trihexyphenidyl were more efficient (14.7 (0.2, 31.3)% per 4 mg/day, p < 0.05) and those prescribed monoamine oxidase-B inhibitor (MAOBI) tended to be more efficient (8.3 (0.0, 17.4)%, p = 0.07). The variance in efficiency was greater within IP (F-test, p = 0.01 adjusted for any demographic covariates: coefficient of variation, with and without IP, 0.68 and 0.46, respectively), but not so after adjustment for anti-parkinsonian medication (p = 0.13: coefficient of variation 0.62). The within-participant follow-up time, a median of 4.8 (interquartile range 3.1, 5.5) years (101 participants), did not influence efficiency, irrespective of IP status. Perception of bradyphrenia did not usefully predict efficiency. We conclude that both bradyphrenia and 'tachyphrenia' in IP appear to have iatrogenic components, of clinically important size, related to the dose of antiparkinsonian medication. Levodopa is the most commonly prescribed first-line medication: co-prescribing a MAOBI may circumvent its associated bradyphrenia. The previously reported greater efficiency associated with (low-dose) anti-muscarinic was confirmed.

Tactile Features of Human Finger Contact Motor Primitives.

The human hand interacts with the environment via physical contact, and tactile information is closely associated with finger movement patterns. Studying the relationship between motor primitives of the finger and the corresponding tactile feedback provides valuable insight into the nature of touch and informs the simulation of humanoid tactile. This research decomposed finger contact into three fundamental motor primitives: contact-on, stick-to-slip, and full slip, then examined the tactile features associated with each motor primitive, including the center of mass (COM) and the centroid of the contact pressure distribution matrix and the total contact area. The change in fingertip contact area during contact-on was in accordance with a first-order kinetic model. In the stick-to-slip, there was a generalized linear relationship between the fingertip skin stretch and the magnitude of the tangential force. Moreover, the skin stretch of the fingertip mirrored the direction of the motion. During the full slip, the COM's movement effectively represented the direction of the tangential force, with an error margin of no more than five degrees. Experiments showed that certain fingertip motions can be portrayed, transmitted, and replicated using tactile information. This research opens potential avenues for remote immersive physical communication in robotics and other related fields.

Diffuse transmittance visible spectroscopy using smartphone flashlight for photoplethysmography and vital signs measurements

Photoplethysmography (PPG), with its wide range of applications, has become one of the most promising modalities for healthcare monitoring technology. In this work, we present a new PPG measurement technique based on diffuse transmittance spectroscopy (DTS) with the help of a smartphone built-in flashlight as an alternative broadband light source. The blood Volume Pulse (BVP) signal was extracted from recorded transmittance spectra at 620 nm. The results were compared with the ground truth and conventional contact finger PPG sensors. A very high correlation was found between the diffuse transmittance signal and the reference PPG signals (r = 0.997, p < 0.0001). The accuracy and root mean square error (RMSE) were 99.23% and 0.8 bpm, respectively. In addition, a Bland-Altman analysis showed a good agreement between both techniques, with a very small bias between mean paired differences of heart rate observations. A simple forward model for diffuse transmittance spectra for different levels of blood oxygen saturation is developed and supported by experimental measurements. It was also found that blood oxygen saturation (SpO2) can be estimated with the aid of DTS based smartphone flash by tracking the wavelength corresponding to the oxygenation level in the visible range between orange and red regions of the visible spectrum particularly in the range between 610 and 635 nm for 26 healthy subjects. 624 nm on average seems to be the wavelength that corresponds with the normal blood oxygenation level. These findings show the potential of DTS PPG to reliably extract cardiac frequency and estimate SpO2 with adequate accuracy. The results also demonstrate the capability of smartphone flash as a miniature visible light source for recording multispectral PPG signals and quantifying vital signs in the transmission mode at the fingertip with acceptable signal quality over a wide range of wavelengths from 550 nm to 650 nm.

A novel rat-tail model for studying human finger vibration health effects.

It has been hypothesized that the biodynamic responses of the human finger tissues to vibration are among the major stimuli that cause vibration health effects. Furthermore, the finger contact pressure can alter these effects. It is difficult to test these hypotheses using human subjects or existing animal models. The objective of this study was to develop a new rat-tail vibration model to investigate the combined effects of vibration and contact pressure and to identify their relationships with the biodynamic responses. Physically, the new exposure system was developed by adding a loading device to an existing rat-tail model. An analytical model of the rat-tail exposure system was proposed and used to formulate the methods for quantifying the biodynamic responses. A series of tests with six tails dissected from rat cadavers were conducted to test and evaluate the new model. The experimental and modeling results demonstrate that the new model behaves as predicted. Unlike the previous model, the vibration strain and stress of the rat tail does not depend primarily on the vibration response of the tail itself but on that of the loading device. This makes it possible to quantify and control the biodynamic responses conveniently and reliably by measuring the loading device response. This study also identified the basic characteristics of the tail biodynamic responses in the exposure system, which can be used to help design the experiments for studying vibration biological effects.

Bioinspired Stabilization of Amorphous Calcium Carbonate by Carboxylated Nanocellulose Enables Mechanically Robust, Healable, and Sensing Biocomposites

Nature builds numerous structurally complex composites with fascinating mechanical robustness and functionalities by harnessing biopolymers and amorphous calcium carbonate (ACC). The key to successfully mimicking these natural designs is efficiently stabilizing ACC, but developing highly efficient, biodegradable, biocompatible, and sustainable stabilizing agents remains a grand challenge since anhydrous ACC is inherently unstable toward crystallization in the wet state. Inspired by the stabilized ACC in crustacean cuticles, we report the efficient stabilization ability of the most abundant biopolymer-cellulose nanofibrils (CNFs) for ACC. Through the cooperative stabilizing effect of surface carboxyl groups and a rigid segregated network, the CNFs exhibit long-term stability (more than one month) and achieved a stabilization efficiency of 3.6 and 4.4 times that of carboxymethyl cellulose (CMC) and alginate, respectively, even higher than poly(acrylic acid). The resulting CNF/ACC dispersions can be constructed into transparent composite films with the high strength of 286 MPa and toughness up to 28.5 MJ/m3, which surpass those of the so far reported synthetic biopolymer-calcium carbonate/phosphate composites. The dynamic interfacial interaction between nanocomponents also provides the composite films with good self-healing properties. Owing to their good wet stability, the composite films present high humidity sensitivity for monitoring respiration and finger contact.

Reconfigurable and Reprocessable Thermadapt Stress‐Free Two‐Way Shape Memory Polymers Based on a Dual Crosslinking Network with Outstanding Mechanical Properties

The reconfigurable and reprocessable thermadapt two‐way shape memory polymers (2W‐SMPs) are highly desirable for many advanced biomimetic applications, but the preparation of these polymers with economical raw materials and convenient approaches still remains a challenge. In this work, thermadapt 2W‐SMPs based on a dual crosslinking network are synthesized by linking polyethylene glycol with hydroxylated modified SBS via dynamic covalent bonds. Benefiting from the synergistic effect of combining a dynamic covalent network and a physical cross‐linking network, the thermadapt 2W‐SMPs exhibit a good balance of mechanical properties and favorable two‐way shape memory effect (2W‐SME) with the reversible actuation strain of 11.9%. The 2W‐SMPs can be reprocessed and transformed into complex 3D shapes after multiple folding processes due to the dynamic covalent exchange as well as the reversible physical crosslinking, and the obtained new samples still exhibit good 2W‐SMEs. Furthermore, the transition temperature of 2W‐SMPs is designed to be close to human body temperature, and it is manufactured into a biomimetic mimosa actuator that can undergo shape changes through finger contact and cooling. This work provides a new idea for the development of thermadapt 2W‐SMPs, and the obtained materials show great potential applications in intelligent actuators.

Tactile Perception of Woven Fabrics by a Sliding Index Finger with Emphasis on Individual Differences

Haptic sensing by sliding fingers over a fabric is a common behavior in consumers when wearing garments. Prior studies have found important characteristics that shape the evaluation criteria and influence the preference of consumers regarding fabrics. This study analyzed the tactile perception of selected woven fabrics, with an emphasis on the participants’ individual differences. Individual differences generally are discarded in sensory experiments by averaging them. Small differences among consumers can be important for understanding the factors driving consumer preferences. For this study, 28 participants assessed fabrics with very distinct surface, compression, and heat transferring properties by sliding their index fingers along the surface of the fabric. The participants also engaged in a descriptive sensory analysis. The physical properties of the fabric were measured using the Kawabata Evaluation System for Fabrics (KES-F) system. Moreover, parameters at the finger–fabric interface, such as the contact force, finger speed, and skin vibration, were measured during the assessment. This study used analysis of variance to eliminate nonsignificant attributes. Consonance analysis was performed using principal component analysis (PCA) on the unfolded sensory and interface data matrices. Finally, the physical and interface data were regressed onto sensory data. The results showed that the contact force and finger speed were nonsignificant, while skin vibration was a possible replacement for surface physical properties measured by the Kawabata Evaluation System for Fabrics (KES-F) system with an equal or slightly improved explainability.

Aligning Exposure Limits for Contact Currents with Exposure Limits for Electric Fields.

The Institute for Electrical and Electronic Engineers (IEEE) and the International Commission on Non-ionizing Radiation Protection (ICNIRP) have established limits for exposures to electromagnetic fields across the 0-300 GHz (non-ionizing) spectrum, including limits on contact currents ( CC ) specified by IEEE for 0-110 MHz (ICNIRP issued a CC "guidance level"). Both sets of limits seek to protect against potentially adverse effects, including aversive electrostimulation at frequencies <100 kHz and excessive heating of tissue at frequencies >100 kHz. For the most part, CC is linked to electric field ( E -field) exposures for an ungrounded person contacting a grounded object, with the short-circuit current ( I SC ) through the contact point (usually the hand) equivalent to the current through the grounded feet of a free-standing person exposed to a vertically polarized E -field. The physical linkage between these two quantities dictates that their respective exposure limits align with one another, which is presently not the case, especially with respect to frequencies from100 kHz to 110 MHz. Here we focus specifically on recommendations for revisions to the IEEE standard, IEEE Std C95.1™-2019 ("IEEE C95.1"), in which the E -field exposure limit ( E -field exposure reference levels, ERL s) >100 kHz induces substantially greater currents than the CC ERL s currently prescribed. The most important scenario deserving of attention concerns finger contact through a 1-cm 2 cross-sectional interface between the skin and a grounded conductor in which the rate of temperature rise in the presence of an E -field ERL can be rapid enough to cause a burn injury. This rate is highly dependent on the moistness/dryness of the skin at the contact point (i.e., its impedance)-a highly variable value-with temperature increasing more rapidly with increasing dryness (greater contact impedance). The two main remedies to alleviate the possibility of injury in this "touch" scenario are to (a) limit the time of finger contact to 1 s in all cases and (b) revise the E -field ERL between 100 kHz and 30 MHz from a "hockey-stick-shaped" curve vs. frequency to a "ramp" across this frequency range. These measures factored in with the real-world prevalence of potentially hazardous scenarios should afford greater protection against adverse outcomes than is presently the case. IEEE C95.1 also specifies limits for grasp contact (15 cm 2 in the palm) and associated wrist heating, plus heating in the ankles from free-standing induction. However, these scenarios are more manageable compared to finger touch due mainly to the comparatively lower rates of tissue heating attributable to the wrist's and ankle's relatively greater cross-sectional area. Recommendations for grasp can thus be dealt with separately. Two identified but unaddressed issues in IEEE C95.1 deserving of further attention are first, the circumstance in which a grounded person contacts an ungrounded object situated in an electric field for which there are countless numbers of scenarios that are not amenable to a single ERL . Second, arcing between an extended limb and E -field-exposed object is perhaps the most hazardous of all scenarios. Both of these scenarios cannot be stereotyped and must be dealt with on a case-by-case basis. Future revisions of IEEE Std C95.1-2019 (and the ICNIRP guidelines) will benefit from improved insight into strategies of affording protection from potentially adverse effects in these circumstances.

ThermoSurf: Thermal Display Technology for Dynamic and Multi-Finger Interactions

Thermal feedback has been proven to enhance user experience in human-machine interactions. Yet state-of-the-art thermal technology has focused on the single finger or palm in static contact, overlooking dynamic and multi-finger interactions. The underlying challenges include incompatible designs of conventional interfaces for providing salient thermal stimuli for such interactions and, thereby, a lack of knowledge on human thermal perception for relevant conditions. Here we present the ThermoSurf, a new thermal display technology that can deliver temperature patterns on a large interface suitable for dynamic and multi-finger interactions. We also investigate how user exploration affects the perception of the generated temperature distributions. Twenty-three human participants interacted with the device following three exploration conditions: static-single finger, dynamic-single finger, and static-multi finger. In these experiments, the individuals evaluated 15 temperature differences ranging from −7.5°C to +1.5°C with an initial temperature of 38°C. Our results showed that human sensitivity against thermal stimuli is significantly greater for static-single finger contact compared to the other tested conditions. In addition, this interaction type resulted in higher thermal discrimination thresholds than the ones reported in the literature. Our findings offer new perspectives on providing salient and consistent thermal feedback for future tactile interfaces.