Multipoint contact pressure for haptic sensory prostheses

PROJECT SUMMARY The human sense of touch plays a crucial role in our perceptual experiences and enabling motor tasks. Amputation, diabetes, stroke, and a host of other diseases result in loss of touch sensation, affecting modalities including vibration, skin deformation, proprioception, temperature, and pain. When haptic sensory loss is localized to a part of the body, or only certain components of touch sensation are missing, haptic stimulation through wearable actuators at an alternative body part or using an alternative haptic modality has been proposed to replace it. The goal of this project is to develop the specifications for wearable devices that act as haptic sensory prostheses, laying the groundwork for later disease-specific implementation and testing. We propose to (1) exploit attributes from both cutaneous and deep tissue sensation to communicate levels of intensity of a signal, and (2) use new methods integrating 3D printed soft actuators with patterned knit enclosures to enable wearable devices that can provide this stimulation. We will invoke spatial summation with larger pressures resulting in deep tissue stimulation to increase the range of applied. A range of pressures and multiple contacts on arm will act as a sensory substitute for missing, low-dimensional haptic sensation elsewhere in the body. We will determine the feasibility and potential of this approach in two aims in both younger and older adults: Aim 1: Identify appropriate pressure intensity range and resolution for multipoint contact pressure. We will measure human perception of single and multipoint contact stimuli. The outcome of this aim will be a characterization of the extent of spatial summation occurring for a range of pressure stimuli and a public dataset for human perception of single and multipoint contact pressures at the stated locations. Aim 2: Characterize the ability of humans to interpret two-degree-of-freedom information from a multipoint contact pressure haptic sensory prosthesis. The outcome of this aim will be a measure of the effectiveness of the deep pressure stimulation devices for improving the control of the arm position. We intentionally scope this R21 proposal to test the highest-risk aspects of this methodology and develop data that leads to future research and implementation to address diseases involving haptic sensory loss by our team and others. Such future research includes the development of wearable haptic devices that meet the identified specifications, characterizing the best type and location of haptic feedback to act as a sensory prosthesis, and understanding and exploiting human adaptation to high-degree-of-freedom mappings between missing and substituted haptic feedback.