Takayuki Kameoka

We present a tactile-sensing method enabled by the mechanical compliance of soft robots: an externally attachable photoreflective module reads surface deformation of silicone skin to estimate contact force while (i) locating the sensing module off the contact interface, (ii) keeping the skin free of embedded transducers/wiring, and (iii) enabling rapid replacement and reconfiguration of the module. Locating the sensor off the contact interface reduces damage risk, and the non-embedded architecture preserves softness while simplifying fabrication and maintenance through a plug-in, replaceable module. We first characterize the optical sensing element and the compliant skin, then determine the design of a prototype tactile sensor. Compression experiments validate the approach, exhibiting a monotonic force–output relationship consistent with theory, low hysteresis, high repeatability over repeated cycles, and small response lag over 0.1–10 mm/s indentation speeds. We further demonstrate integration on a soft robotic gripper, where the module reliably detects grasp events. Compared with liquid-filled or wire-embedded tactile skins, the proposed modular “add-on” architecture enhances durability, reduces wiring complexity, and supports easy redeployment across diverse robot geometries without disassembling the robot skin. Because the sensing principle reads skin-strain patterns, it also suggests extensions to other somatosensory cues—such as join-tangle or actuator-state estimation—from surface deformation. Overall, leveraging surface compliance with an external optical module provides a practical and robust route to equip soft robots with force perception while preserving structural flexibility and manufacturability, paving the way for robotic applications and safe human–robot collaboration.

Tactile perception is essential for material recognition, with thermal transients playing a key role in conveying information about object material composition. This study evaluates the performance of a thermal contact sensor designed to capture the characteristics of skin thermal responses during contact with a wide range of materials. The sensor, constructed using a heat-resistant glass contact surface and an integrated heating system, was evaluated by comparing temperature responses with human fingers when contacting materials. Experimental results showed that while the thermal contact sensor successfully captured material-dependent temperature responses, differences in heat transfer dynamics between the sensor and human fingers were observed in the initial cooling rate and total temperature change during contact. Although the sensor differs from the human finger, it has its own unique characteristics and provides valuable responses for material recognition. To further enhance its performance, incorporating a soft material could improve contact with different surfaces, potentially refining its thermal response. The thermal contact sensor has significant potential for creating large-scale thermal datasets, which could advance applications in haptic displays and robotic material recognition systems.

We present ExtEdge, a design and method for augmenting the visual experiences of a smartphone using electro-tactile stimulation. We aim to explore new interactions through tactile augmentation of visual information, such as virtual characters, at the edges of the screen. ExtEdge presents distributed tactile sensations through electrical stimulations from electrode arrays mounted on both edges of the smartphone. This distributed tactile stimulus fits the image at the edges of the screen and provides a more realistic presentation. We first investigated two-point discrimination thresholds in the contact areas of the grasp—middle finger, ring finger, thumb, and thenar eminence—as a performance evaluation of the distributed tactile presentation and found that our design was adequate. We then conducted a user study with some application scenarios and confirmed that ExtEdge enriches visual information.

We present LivEdge, a novel method for live stream interaction on smartphones utilizing electro-tactile sensation through the edges. Conventional interactions between users and a streamer on a smartphone are restricted to the streamer’s response through user comments or effects. Our goal is to provide a more immersive interaction through the use of haptic technology. LivEdge can convey spatial tactile sensations through electrical stimulations from electrode arrays affixed to both edges of the smartphone. This spatial tactile stimulus represents the streamer’s physical presence and movements in contact with the edge of the screen. Preliminary experiment showed LivEdge enhances the live stream experience.

To enrich the virtual reality experience and improve realism, many studies have proposed embedding tactile devices into head-mounted displays (HMDs). However, although thermal and vibrotactile cues have become commonplace, presentation of the constant pressure necessary for softness expression remains relatively rare. In this study, we propose a suction-type tactile presentation method that addresses this issue. Through subjective evaluation and simulation using the finite element method, we verified that the proposed suction-type tactile presentation method is suitable for use with HMDs and that by increasing the number and density of the suction holes, a stronger tactile sensation can be created.

The quantification of stickiness experienced upon touching a sticky or adhesive substance has attracted intense research attention, particularly for application to haptics, virtual reality, and human–computer interactions. Here, we develop and evaluate a device that quantifies the feeling of stickiness experienced upon touching an adhesive substance. Keeping in mind that a typical pressure distribution sensor can only measure a pressing force, but not a tensile force, in our setup, we apply an offset pressure to a pressure distribution sensor and measure the tensile force generated by an adhesive substance as the difference from the offset pressure. We propose a method of using a magnetic force to generate the offset pressure and develop a measuring device using a magnet that attracts magnetic pin arrays and pin magnets; the feasibility of the method is verified with a first prototype. We develop a second prototype that overcomes the noise problems of the first, arising from the misalignment of the pins owing to the bending of the magnetic force lines at the sensor edges. We also obtain measurement results for actual samples and standard viscosity liquids. Our findings indicate the feasibility of our setup as a suitable device for measuring stickiness.