Rendering volumetric haptic shapes in mid-air using ultrasound

We present a method for creating three-dimensional haptic shapes in mid-air using focused ultrasound. This approach applies the principles of acoustic radiation force, whereby the non-linear effects of sound produce forces on the skin which are strong enough to generate tactile sensations. This mid-air haptic feedback eliminates the need for any attachment of actuators or contact with physical devices. The user perceives a discernible haptic shape when the corresponding acoustic interference pattern is generated above a precisely controlled two-dimensional phased array of ultrasound transducers. In this paper, we outline our algorithm for controlling the volumetric distribution of the acoustic radiation force field in the form of a three-dimensional shape. We demonstrate how we create this acoustic radiation force field and how we interact with it. We then describe our implementation of the system and provide evidence from both visual and technical evaluations of its ability to render different shapes. We conclude with a subjective user evaluation to examine users’ performance for different shapes

SensaBubble: a chrono-sensory mid-air display of sight and smell

We present SensaBubble, a chrono-sensory mid-air display system that generates scented bubbles to deliver information to the user via a number of sensory modalities. The system reliably produces single bubbles of specific sizes along a directed path. Each bubble produced by SensaBubble is filled with fog containing a scent relevant to the notification. The chrono-sensory aspect of SensaBubble means that information is presented both temporally and multimodally. Temporal information is enabled through two forms of persistence: firstly, a visual display projected onto the bubble which only endures until it bursts; secondly, a scent released upon the bursting of the bubble slowly disperses and leaves a longer-lasting perceptible trace of the event. We report details of SensaBubble’s design and implementation, as well as results of technical and user evaluations. We then discuss and demonstrate how SensaBubble can be adapted for use in a wide range of application contexts – from an ambient peripheral display for persistent alerts, to an engaging display for gaming or education

Thermotactile thresholds at the fingertip: effect of contact area and contact location

Thresholds for the detection of changes in temperature are used to indicate neuropathy, but a variety of different contact areas and contact locations are used. This study was designed to determine the effects of variations in contact area and contact location on both warm and cool thresholds at the fingertip. With 20 healthy subjects (10 females and 10 males aged 20–30 years), warm thresholds and cool thresholds were determined in two separate sessions using the method of limits. In the first part of each session, thresholds were determined around the centre of the whorl using circular contactors with five different diameters (3, 6, 9, 12, and 55 mm). In the second part of each session, thresholds were determined using two contactors (6- and 12-mm diameter) at three locations along the fingertip: (i) distal (5 mm from the nail), (ii) middle (centre of whorl), and (iii) proximal (3 mm from the distal interphalangeal joint). With increasing contact area, the warm thresholds decreased, the cool thresholds increased, and the inter-subject variability in both warm and cool thresholds decreased. Using the 6-mm diameter contactor, warm thresholds were independent of location but cool thresholds increased from distal to proximal locations. It is concluded that temperature sensitivity at the fingertip increases with increasing area of contact, with the variability in thresholds consistent with the existence of warm and cool “insensitive fields”. The findings show that the influence of contact area and contact location should be considered when assessing thermotactile thresholds at the fingertip.<br/

Thermotactile thresholds before, during and after exposure to hand-transmitted vibration

Warm and cool thresholds before, during, and after exposure to vibration, were investigated. Twelve healthy male volunteers with a mean age of 26.3 years participated in the study. Subjects were screened to exclude those with prior regular exposure to hand-transmitted vibration, diabetes, vascular or neurological disorders and injuries to the right hand. The experiment was performed in a room with ambient temperature of 23°C. Subjects were acclimatised for 10 minutes before the skin temperatures were measured. During the pre-exposure period, there is no significant difference in thresholds between the control condition and the 125-Hz session. With 125-Hz vibration, warm thresholds increased over the five periods and also over the three periods during application of vibration

Talking about tactile experiences

A common problem with designing and developing applications with tactile interfaces is the lack of a vocabulary that allows one to describe or communicate about haptics. Here we present the findings from a study exploring participants’ verbalizations of their tactile experiences across two modulated tactile stimuli (16Hz and 250Hz) related to two important mechanoreceptors in the human hand. The study, with 14 participants, applied the explicitation interview technique to capture detailed descriptions of the diachronic and synchronic structure of tactile experiences. We propose 14 categories for a human- experiential vocabulary based on the categorization of the findings and tie them back to neurophysiological and psychophysical data on the human hand. We finally discuss design opportunities created through this experiential understanding in relation to the two mechanoreceptors

Need for touch in human space exploration: towards the design of a morphing haptic glove – ExoSkin

The spacesuit, particularly the spacesuit glove, creates a barrier between astronauts and their environment. Motivated by the vision of facilitating full-body immersion for effortless space exploration, it is necessary to understand the sensory needs of astronauts during extra-vehicular activities (EVAs). In this paper, we present the outcomes from a two-week field study performed at the Mars Desert Research Station, a facility where crews carry out Mars-simulated missions. We used a combination of methods (a haptic logbook, technology probes, and interviews) to investigate user needs for haptic feedback in EVAs in order to inform the design of a haptic glove. Our results contradict the common belief that a haptic technology should always convey as much information as possible, but should rather offer a controllable transfer. Based on these findings, we identified two main design requirements to enhance haptic feedback through the glove: (i) transfer of the shape and pressure features of haptic information and (ii) control of the amount of haptic information. We present the implementation of these design requirements in the form of the concept and first prototype of ExoSkin. ExoSkin is a morphing haptic feedback layer that augments spacesuit gloves by controlling the transfer of haptic information from the outside world onto the astronauts’ skin

Ghost touch: turning surfaces into interactive tangible canvases with focused ultrasound

Digital art technologies take advantage of the input, output and processing capabilities of modern computers. However, full digital systems lack the tangibility and expressiveness of their traditional counterparts. We present Ghost Touch, a system that remotely actuate the artistic medium with an ultrasound phased array. Ghost Touch transforms a normal surface into an interactive tangible canvas in which the users and the system collaborate in real-time to produce an artistic piece. Ghost Touch is able to detect traces and reproduce them, therefore enabling common digital operations such as copy, paste, save or load whilst maintaining the tangibility of the traditional medium. Ghost Touch has enhanced expressivity since it uses a novel algorithm to generate multiple ultrasound focal points with specific intensity levels. Different artistic effects can be performed on sand, milk&ink or liquid soap