Creative Probes, Proxy Feelers, and Speculations on Interactive Skin

This paper critically discusses the combination of creative and social research methods to generate a novel approach to explore the multimodal technoscape. This paper draws on an interdisciplinary exploratory case study on interactive skin—an emergent technology that augments and/or interacts with the skin. This paper shows how concepts from skin studies and the HCI literature can be used to draw on creative methods to think about and with the body. We describe the use of an online probe pack, a speculative research workshop and sensory research interviews using ‘proxy feelers’ to agitate the design space of interactive skin futures. We show how combining these methods provoked and expanded the scope of interactive skin from the technological to the sensory and the social. We discuss the opportunities and challenges of the research dialogues that this approach facilitated, make the case for creative methodological improvisation and exploration of emergent technologies and show how creative and social research methods can be combined to explore the interconnection between technology, society and design

Gamma Band Oscillation Response to Somatosensory Feedback Stimulation Schemes Constructed on Basis of Biphasic Neural Touch Representation

abstract: Prosthetic users abandon devices due to difficulties performing tasks without proper graded or interpretable feedback. The inability to adequately detect and correct error of the device leads to failure and frustration. In advanced prostheses, peripheral nerve stimulation can be used to deliver sensations, but standard schemes used in sensorized prosthetic systems induce percepts inconsistent with natural sensations, providing limited benefit. Recent uses of time varying stimulation strategies appear to produce more practical sensations, but without a clear path to pursue improvements. This dissertation examines the use of physiologically based stimulation strategies to elicit sensations that are more readily interpretable. A psychophysical experiment designed to investigate sensitivities to the discrimination of perturbation direction within precision grip suggests that perception is biomechanically referenced: increased sensitivities along the ulnar-radial axis align with potential anisotropic deformation of the finger pad, indicating somatosensation uses internal information rather than environmental. Contact-site and direction dependent deformation of the finger pad activates complimentary fast adapting and slow adapting mechanoreceptors, exhibiting parallel activity of the two associate temporal patterns: static and dynamic. The spectrum of temporal activity seen in somatosensory cortex can be explained by a combined representation of these distinct response dynamics, a phenomenon referred in this dissertation to “biphasic representation.” In a reach-to-precision-grasp task, neurons in somatosensory cortex were found to possess biphasic firing patterns in their responses to texture, orientation, and movement. Sensitivities seem to align with variable deformation and mechanoreceptor activity: movement and smooth texture responses align with potential fast adapting activation, non-movement and coarse texture responses align with potential increased slow adapting activation, and responses to orientation are conceptually consistent with coding of tangential load. Using evidence of biphasic representations’ association with perceptual priorities, gamma band phase locking is used to compare responses to peripheral nerve stimulation patterns and mechanical stimulation. Vibrotactile and punctate mechanical stimuli are used to represent the practical and impractical percepts commonly observed in peripheral nerve stimulation feedback. Standard patterns of constant parameters closely mimic impractical vibrotactile stimulation while biphasic patterns better mimic punctate stimulation and provide a platform to investigate intragrip dynamics representing contextual activation.Dissertation/ThesisDoctoral Dissertation Biomedical Engineering 201

Prevalence of haptic feedback in robot-mediated surgery : a systematic review of literature

© 2017 Springer-Verlag. This is a post-peer-review, pre-copyedit version of an article published in Journal of Robotic Surgery. The final authenticated version is available online at: https://doi.org/10.1007/s11701-017-0763-4With the successful uptake and inclusion of robotic systems in minimally invasive surgery and with the increasing application of robotic surgery (RS) in numerous surgical specialities worldwide, there is now a need to develop and enhance the technology further. One such improvement is the implementation and amalgamation of haptic feedback technology into RS which will permit the operating surgeon on the console to receive haptic information on the type of tissue being operated on. The main advantage of using this is to allow the operating surgeon to feel and control the amount of force applied to different tissues during surgery thus minimising the risk of tissue damage due to both the direct and indirect effects of excessive tissue force or tension being applied during RS. We performed a two-rater systematic review to identify the latest developments and potential avenues of improving technology in the application and implementation of haptic feedback technology to the operating surgeon on the console during RS. This review provides a summary of technological enhancements in RS, considering different stages of work, from proof of concept to cadaver tissue testing, surgery in animals, and finally real implementation in surgical practice. We identify that at the time of this review, while there is a unanimous agreement regarding need for haptic and tactile feedback, there are no solutions or products available that address this need. There is a scope and need for new developments in haptic augmentation for robot-mediated surgery with the aim of improving patient care and robotic surgical technology further.Peer reviewe

Assessment of lingual tactile sensitivity in children and adults: methodological suitability and challenges

Few methodological approaches have been developed to measure lingual tactile sensitivity, and little information exists about the comparison between children and adults. The aims of the study were to: verify the cognitive and perceptive suitability of Von Frey filaments and a gratings orientation test in children of different ages; compare lingual tactile sensitivity between children and adults; investigate the relationships between lingual tactile sensitivity, preference and consumption of foods with different textures and level of food neophobia. One hundred and forty-seven children aged 6–13 years and their parents participated in the study, in addition to a separate sample of seventy adults. Participants filled in questionnaires, and lingual tactile sensitivity was evaluated through filaments and gratings. Results showed that gratings evaluation was more difficult than filaments assessment but enabled a better separation of participants according to their performance than filaments. R-indices from filaments were not correlated with those of gratings, suggesting that the tools measure different dimensions of lingual tactile sensitivity. No differences were found in lingual tactile sensitivity between children and adults, nor between children of different ages. Food neophobia was negatively associated with preferences of hard foods in children. Although a multifactor analysis concluded that neither texture preferences nor food consumption were strongly correlated with lingual tactile sensitivity, there was a weak but significant positive correlation between lingual tactile sensitivity to the finest Von Frey filament and food neophobia in the youngest age group, indicating that children with higher levels of food neophobia are more sensitive to oral tactile stimuli. Suitable child-friendly adaptations for the assessment of lingual sensitivity in children are discussed

Feeling Small: Exploring the Tactile Perception Limits

The human finger is exquisitely sensitive in perceiving different materials, but the question remains as to what length scales are capable of being distinguished in active touch. We combine material science with psychophysics to manufacture and haptically explore a series of topographically patterned surfaces of controlled wavelength, but identical chemistry. Strain-induced surface wrinkling and subsequent templating produced 16 surfaces with wrinkle wavelengths ranging from 300 nm to 90 μm and amplitudes between 7 nm and 4.5 μm. Perceived similarities of these surfaces (and two blanks) were pairwise scaled by participants, and interdistances among all stimuli were determined by individual differences scaling (INDSCAL). The tactile space thus generated and its two perceptual dimensions were directly linked to surface physical properties – the finger friction coefficient and the wrinkle wavelength. Finally, the lowest amplitude of the wrinkles so distinguished was approximately 10 nm, demonstrating that human tactile discrimination extends to the nanoscale

Tribology of Skin: Review and Analysis of Experimental Results for the Friction Coefficient of Human Skin

In this review, we discuss the current knowledge on the tribology of human skin and present an analysis of the available experimental results for skin friction coefficients. Starting with an overview on the factors influencing the friction behaviour of skin, we discuss the up-to-date existing experimental data and compare the results for different anatomical skin areas and friction measurement techniques. For this purpose, we also estimated and analysed skin contact pressures applied during the various friction measurements. The detailed analyses show that substantial variations are a characteristic feature of friction coefficients measured for skin and that differences in skin hydration are the main cause thereof, followed by the influences of surface and material properties of the contacting materials. When the friction coefficients of skin are plotted as a function of the contact pressure, the majority of the literature data scatter over a wide range that can be explained by the adhesion friction model. The case of dry skin is reflected by relatively low and pressure-independent friction coefficients (greater than 0.2 and typically around 0.5), comparable to the dry friction of solids with rough surfaces. In contrast, the case of moist or wet skin is characterised by significantly higher (typically >1) friction coefficients that increase strongly with decreasing contact pressure and are essentially determined by the mechanical shear properties of wet skin. In several studies, effects of skin deformation mechanisms contributing to the total friction are evident from friction coefficients increasing with contact pressure. However, the corresponding friction coefficients still lie within the range delimited by the adhesion friction model. Further research effort towards the analysis of the microscopic contact area and mechanical properties of the upper skin layers is needed to improve our so far limited understanding of the complex tribological behaviour of human ski

Adaptation to moving tactile stimuli and its effects on perceived speed and direction

Like other senses, tactile perception is subject to adaptation effects in which systematic changes in the pattern of sensory input lead to predictable changes in perception. In this thesis, aftereffects of adaptation to tactile motion are used to reveal the processes that give rise to tactile motion perception from the relevant sensory inputs. The first aftereffect is the tactile speed aftereffect (tSAE), in which the speed of motion appears slower following exposure to a moving surface. Perceived speed of a test surface was reduced by about 30% regardless of the direction of the adapting stimulus, indicating that the tSAE is not direction sensitive. Additionally, higher adapting speeds produced a stronger tSAE, and this dependence on adapting speed could not be attributed to differences in temporal frequency or spatial period that accompanied the different adapting speeds. The second motion aftereffect that was investigated is the dynamic tactile motion aftereffect (tMAE), in which a direction-neutral test stimulus appears to move in the opposite direction to previously felt adapting motion. The strength of the tMAE depended on the speed of the adapting motion, with higher speeds producing a stronger aftereffect. Both the tSAE and the tMAE showed evidence of an intensive speed code in their underlying neural populations, with faster adapting speeds resulting in stronger aftereffects. In neither case was any evidence of speed tuning found, that is, neither aftereffect was strongest with a match between the speeds of the adapting and test stimuli. This is compatible with the response properties of motion sensitive neurons in the primary somatosensory cortex. Despite these shared features, speed and direction are unlikely to be jointly coded in the same neurons because the lack of direction sensitivity of the tSAE requires neural adaptation effects to be uniform across neurons preferring all directions, whereas the tMAE requires direction selective adaptation

Adaptation to moving tactile stimuli and its effects on perceived speed and direction

Like other senses, tactile perception is subject to adaptation effects in which systematic changes in the pattern of sensory input lead to predictable changes in perception. In this thesis, aftereffects of adaptation to tactile motion are used to reveal the processes that give rise to tactile motion perception from the relevant sensory inputs. The first aftereffect is the tactile speed aftereffect (tSAE), in which the speed of motion appears slower following exposure to a moving surface. Perceived speed of a test surface was reduced by about 30% regardless of the direction of the adapting stimulus, indicating that the tSAE is not direction sensitive. Additionally, higher adapting speeds produced a stronger tSAE, and this dependence on adapting speed could not be attributed to differences in temporal frequency or spatial period that accompanied the different adapting speeds. The second motion aftereffect that was investigated is the dynamic tactile motion aftereffect (tMAE), in which a direction-neutral test stimulus appears to move in the opposite direction to previously felt adapting motion. The strength of the tMAE depended on the speed of the adapting motion, with higher speeds producing a stronger aftereffect. Both the tSAE and the tMAE showed evidence of an intensive speed code in their underlying neural populations, with faster adapting speeds resulting in stronger aftereffects. In neither case was any evidence of speed tuning found, that is, neither aftereffect was strongest with a match between the speeds of the adapting and test stimuli. This is compatible with the response properties of motion sensitive neurons in the primary somatosensory cortex. Despite these shared features, speed and direction are unlikely to be jointly coded in the same neurons because the lack of direction sensitivity of the tSAE requires neural adaptation effects to be uniform across neurons preferring all directions, whereas the tMAE requires direction selective adaptation