Published papers

The hand fingerpad is one of the sensitive parts in human body. It can detect the surface features such as bumps and holes very quickly. However, the algorithm how we recognize such surface features in the brain has not been well studied. This study investigates human surface form recognition in terms of both psychological shape recognition performance for surface features and mechanical deformation produced by surface features. We utilized the finite element model of fingerpad which mimics the anatomical structure of finger tissue, and calculated the mechanical deformation in contacting indented or raised surface. We analyzed the deformation pattern in terms of the strain energy density in the locations where Merkel cells are typically observed. By comparing previous study on the human surface form recognition performance in fingerpad, we propose tactile recognition algorithm for identifying whether the surface form is raised or indented. The outcome of this research is not only valuable for comprehending the tactile recognition algorithm in human, but also insightful for developing tactile sensors which enables to detect surface form features.

Current Haptics technology is capable of manipulating the tactile perception of material properties. Although Haptics research is very popular in academic research, those technologies have not prevailed in general use yet. Here we report the development of an introductory haptic device called the "TECHTILE toolkit" that is capable of designing haptic experiences. We conducted usability study of our developed toolkit through conducting over fifty workshops world-wide that are for both professional researchers and general audience from elementary to collage levels. We also discuss the prospective applications of haptic devices by classifying participants' haptic experiences that were proposed during the workshop.

© 2019 IEEE. A basic challenge in perception research is to understand how sensory inputs from physical environments and the body are integrated in order to facilitate perceptual inferences. Thermal perception, which arises through heat transfer between extrinsic sources and body tissues, is an integral part of natural haptic experiences, and thermal feedback technologies have potential applications in wearable computing, virtual reality, and other areas. While physics dictates that thermal percepts can be slow, often unfolding over timescales measured in seconds, much faster perceptual responses can occur in the thermal grill illusion. The latter refers to a burning-like sensation that can be evoked when innocuous warm and cool stimuli are applied to the skin in juxtaposed fashion. Here, we show that perceptual response times to the thermal grill illusion decrease systematically with perceived intensity. Using results from behavioral experiments in combination with a physics-based description of tissue heating, we develop a simple model explaining the perception of the illusion through the evolution of internal tissue temperatures. The results suggest that improved understanding of the physical mechanisms of tissue heating may aid our understanding of thermal perception, as exemplified by the thermal grill illusion, and might point toward more efficient methods for thermal feedback.