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High-spatial-resolution wearable tactile arrays have drawn interest from both industry and research, thanks to their capacity for delivering detailed tactile sensations. However, investigations of human tactile perception with high resolution tactile displays remain limited, primarily due to the high costs of multi-channel control systems and the complex fabrication required for fingertip-sized actuators. In this work, we introduce the Soft Haptic Display (SHD) toolkit, designed to enable students and researchers from diverse technical backgrounds to explore high-density tactile feedback in extended reality (XR), robotic teleoperation, braille displays, navigation aid, MR-compatible somatosensory stimulation, and remote palpation. The toolkit provides a rapid prototyping approach and real-time wireless control for a low-cost, 4×4 soft wearable fingertip tactile display with a spatial resolution of 4 mm. We characterized the display’s performance with a maximum vertical displacement of 1.8 mm, a rise time of 0.25 second, and a maximum refresh rate of 8 Hz. All materials and code are open-sourced to foster broader human tactile perception research of high-resolution haptic displays. 

Medical palpation is a task that traditionally requires a skilled practitioner to assess and diagnose a patient through direct touch and manipulation of their body. In regions with a shortage of such professionals, robotic hands or sensorized gloves could potentially capture the necessary haptic information during palpation exams and relay it to medical doctors for diagnosis. From an engineering perspective, a comprehensive understanding of the relevant motions and forces is essential for designing haptic technologies capable of fully capturing this information. This study focuses on thyroid examination palpation, aiming to analyze the hand motions and forces applied to the patient’s skin during the procedure. We identified key palpation techniques through video recordings and interviews and measured the force characteristics during palpation performed by both non-medical participants and medical professionals. Our findings revealed five primary palpation hand motions and characterized the multi-dimensional interaction forces involved in these motions. These insights provide critical design guidelines for developing haptic sensing and display technologies optimized for remote thyroid nodule palpation and diagnosis. 

Thermal perception is important in the experience of touching real objects, and thermal display devices are of growing interest for applications in virtual reality, medicine, and wearable technologies. In this paper, we designed a new thermal display, and investigated the perception of spatially varying thermal stimuli, including the thermal grill illusion. The latter is a perceptual effect in which a burning sensation is elicited in response to touching a surface composed of spatially juxtaposed warm and cool areas. Using a computer controlled thermal display, we present experiments in which we measured temporal correlates of the perception of spatially inhomogeneous stimuli, or thermal grills. We assessed the intensity of responses elicited by thermal grill stimuli with different temperature settings, and measured the response time until the onset of burning sensations. We found that thermal grills elicited highly stereotyped responses. The experimental results also indicated that as the temperature difference increases, the intensity increases monotonically, while the response time decreases monotonically. Consequently, perceived intensity was inversely correlated with response time. Under current physiological explanations, responses to thermal stimuli depend on tissue heating, neural processing, and the spatial distribution (or juxtaposition) of surface temperatures. The results of this study could help to inform models accounting for these factors, enabling new applications of the thermal grill illusion.