Bioelastic state recovery for haptic sensory substitution.

The rich set of mechanoreceptors found in human skin offers a versatile engineering interface for transmitting information and eliciting perceptions, potentially serving a broad range of applications in patient care and other important industries. Targeted multisensory engagement of these afferent units, however, faces persistent challenges, especially for wearable, programmable systems that need to operate adaptively across the body. Here we present a miniaturized electromechanical structure that, when combined with skin as an elastic, energy-storing element, supports bistable, self-sensing modes of deformation.

Realism of Tactile Texture Playback: A Combination of Stretch and Vibration.

This study investigates the effects of two stimulation modalities (stretch and vibration) on natural touch sensation on the volar forearm. The skin-textile interaction was implemented by scanning three textures across the left forearm. The resulting skin displacements were recorded by the digital image correlation technique to capture the information imparted by the textures.

The Single-Pitch Texel: A flexible and practical texture-rendering algorithm.

As the number of applications for tactile feedback technology rapidly increases, so too does the need for efficient, flexible, and extensible representations of virtual textures. The previously introduced Single-Pitch Texel rendering algorithm offers designers the ability to produce textures with perceptually wide-band spectral characteristics while requiring very few input parameters. This paper expands on the capabilities of the rendering algorithm.

The spatial profile of skin indentation shapes tactile perception across stimulus frequencies.

Multiple human sensory systems exhibit sensitivity to spatial and temporal variations of physical stimuli. Vision has evolved to offer high spatial acuity with limited temporal sensitivity, while audition has developed complementary characteristics. Neural coding in touch has been believed to transition from a spatial to a temporal domain in relation to surface scale, such that coarse features (e.

A Low-Parameter Rendering Algorithm for Fine Textures.

This paper introduces a novel rendering algorithm for virtual textures, specifically those with characteristic length scales below 1 mm. By leveraging the relatively lossy mode of human tactile perception at this length scale, a virtual texture with wide-band spectral characteristics can be reduced to a spatial sequence of single-frequency texels, where each frequency is pulled stochastically from a distribution. A psychophysical study was conducted to demonstrate that, below a limiting physical texel length, virtual textures defined by identical frequency distributions are perceptually indiscriminable.

Data-Driven Playback of Natural Tactile Texture Via Broadband Friction Modulation.

We used broadband electroadhesion to reproduce the friction force profile measured as a finger slid across a textured surface. In doing so, we were also able to reproduce with high fidelity the skin vibrations characteristic of that texture; however, we found that this did not reproduce the original perception. To begin, the reproduction felt weak.

Building a Navigable Fine Texture Design Space.

Friction modulation technology enables the creation of textural effects on flat haptic displays. However, an intuitive and manageably small design space for construction of such haptic textures remains an unfulfilled goal for user interface designers. In this paper, we explore perceptually relevant features of fine texture for use in texture construction and modification.

Comparison of Wide-Band Vibrotactile and Friction Modulation Surface Gratings.

This article seeks to understand conditions under which virtual gratings produced via vibrotaction and friction modulation are perceived as similar and to find physical origins in the results. To accomplish this, we developed two single-axis devices, one based on electroadhesion and one based on out-of-plane vibration. The two devices had identical touch surfaces, and the vibrotactile device used a novel closed-loop controller to achieve precise control of out-of-plane plate displacement under varying load conditions across a wide ranget of frequencies.

How the Mechanical Properties and Thickness of Glass Affect TPaD Performance.

One well-known class of surface haptic devices that we have called Tactile Pattern Displays (TPaDs) uses ultrasonic transverse vibrations of a touch surface to modulate fingertip friction. This article addresses the power consumption of glass TPaDs, which is an important consideration in the context of mobile touchscreens. In particular, based on existing ultrasonic friction reduction models, we consider how the mechanical properties (density and Young's modulus) and thickness of commonly-used glass formulations affect TPaD performance, namely the relation between its friction reduction ability and its real power consumption.

Localizable Button Click Rendering via Active Lateral Force Feedback.

In this article, we have developed a novel button click rendering mechanism based on active lateral force feedback. The effect can be localized because electroadhesion between a finger and a surface can be localized. Psychophysical experiments were conducted to evaluate the quality of a rendered button click, which subjects judged to be acceptable.

Electrowetting: A Consideration in Electroadhesion.

With the commercialization of haptic devices, understanding behavior under various environmental conditions is crucial for product optimization and cost reduction. Specifically, for surface haptic devices, the dependence of the friction force and the electroadhesion effect on the environmental relative humidity and the finger hydration level can directly impact their design and performance. This article presents the influence of relative humidity on the finger-surface friction force and the electroadhesion performance.

Closed Loop Application of Electroadhesion for Increased Precision in Texture Rendering.

Tactile displays based on friction modulation offer wide-bandwidth forces rendered directly on the fingertip. However, due to a number of touch conditions (e.g.

UltraShiver: Lateral Force Feedback on a Bare Fingertip via Ultrasonic Oscillation and Electroadhesion.

We propose a new lateral force feedback device, the UltraShiver, which employs a combination of in-plane ultrasonic oscillation (around 30 kHz) and out-of-plane electroadhesion. It can achieve a strong active lateral force (400 mN) on the bare fingertip while operating silently. The lateral force is a function of pressing force, lateral vibration velocity, and electroadhesive voltage, as well as the relative phase between the velocity and voltage.

The Application of Tactile, Audible, and Ultrasonic Forces to Human Fingertips Using Broadband Electroadhesion.

We report an electroadhesive approach to controlling friction forces on sliding fingertips which is capable of producing vibrations across an exceedingly broad range of tactile, audible, and ultrasonic frequencies. Vibrations on the skin can be felt directly, and vibrations in the air can be heard emanating from the finger. Additionally, we report evidence from an investigation of the electrical dynamics of the system suggesting that an air gap at the skin/surface interface is primarily responsible for the induced electrostatic attraction underlying the electroadhesion effect.

eShiver: Lateral Force Feedback on Fingertips through Oscillatory Motion of an Electroadhesive Surface.

We describe a new haptic force feedback device capable of creating lateral shear force on a bare fingertip-the eShiver. The eShiver creates a net lateral force from in-plane oscillatory motion of a surface synchronized with a "friction switch" based on Johnsen-Rahbek electroadhesion. Using an artificial finger, a maximum net lateral force of ±300 mN is achieved at 55 Hz lateral oscillation frequency, and net force is shown to be a function of velocity and applied voltage, as well as the phase between them.

Partial squeeze film levitation modulates fingertip friction.

When touched, a glass plate excited with ultrasonic transverse waves feels notably more slippery than it does at rest. To study this phenomenon, we use frustrated total internal reflection to image the asperities of the skin that are in intimate contact with a glass plate. We observed that the load at the interface is shared between the elastic compression of the asperities of the skin and a squeeze film of air.

Multiple Fingers - One Gestalt.

The Gestalt theory of perception offered principles by which distributed visual sensations are combined into a structured experience ("Gestalt"). We demonstrate conditions whereby haptic sensations at two fingertips are integrated in the perception of a single object. When virtual bumps were presented simultaneously to the right hand's thumb and index finger during lateral arm movements, participants reported perceiving a single bump.

Coincidence avoidance principle in surface haptic interpretation.

When multiple fingertips experience force sensations, how does the brain interpret the combined sensation? In particular, under what conditions are the sensations perceived as separate or, alternatively, as an integrated whole? In this work, we used a custom force-feedback device to display force signals to two fingertips (index finger and thumb) as they traveled along collinear paths. Each finger experienced a pattern of forces that, taken individually, produced illusory virtual bumps, and subjects reported whether they felt zero, one, or two bumps. We varied the spatial separation between these bump-like force-feedback regions, from being much greater than the finger span to nearly exactly the finger span.

Search efficiency for tactile features rendered by surface haptic displays.

Haptic interfaces controlled by a single fingertip or hand-held probe tend to display surface features individually, requiring serial search for multiple features. Novel surface haptic devices, however, have the potential to provide displays to multiple fingertips simultaneously, affording the possibility of parallel search. Using variable-friction surface haptic devices, we investigated the ability of participants to detect a target feature among a set of distractors in parallel across the fingers.

Power optimization of ultrasonic friction-modulation tactile interfaces.

Ultrasonic friction-modulation devices provide rich tactile sensation on flat surfaces and have the potential to restore tangibility to touchscreens. To date, their adoption into consumer electronics has been in part limited by relatively high power consumption, incompatible with the requirements of battery-powered devices. This paper introduces a method that optimizes the energy efficiency and performance of this class of devices.

Small-scale spatial variation in population dynamics and fishermen response in a coastal marine fishery.

A major challenge for small-scale fisheries management is high spatial variability in the demography and life history characteristics of target species. Implementation of local management actions that can reduce overfishing and maximize yields requires quantifying ecological heterogeneity at small spatial scales and is therefore limited by available resources and data. Collaborative fisheries research (CFR) is an effective means to collect essential fishery information at local scales, and to develop the social, technical, and logistical framework for fisheries management innovation.

Haptic feedback enhances grip force control of sEMG-controlled prosthetic hands in targeted reinnervation amputees.

In this study, we hypothesized that haptic feedback would enhance grip force control of surface electromyography (sEMG)-controlled prosthetic hands for targeted reinnervation (TR) amputees. A new miniature haptic device, a tactor, that can deliver touch, pressure, shear, and temperature sensation, allows modality-matching haptic feedback. TR surgery that creates sensory regions on the patient's skin that refer to the surface of the missing limb allows somatotopic-matching haptic feedback.