Toward a Wearable Tactile Sensory Amplification Device: Transfer Characteristics and Optimization

This project aims to create a wearable device capable of electronically enhancing touch, in the same way that a hearing aid enhances the auditory sense. Our prototype device utilizes electronic sensors, in the form of wide bandwidth MEMS accelerometers, that are worn on the finger to capture touch-induced skin vibrations, which are instrumental to haptic perception. Active, analog electronics are used to filter and amplify the resulting signals without digitization. A compact recoil actuator is used to accurately reproduce these signals, effectively enhancing the transient touch information that is produced when the finger contacts or slides against an object. In order to optimize the performance of this device, we measured and analyzed the frequency-domain transfer characteristics of this system. The results were used to determine sensor and actuator locations and orientations that would minimize feedback, increasing the range of feasible amplification gains. This study may help to guide the design of sensory prostheses and haptic displays worn on the upper limb. Such devices could be beneficial for individuals with impaired touch sensation due to peripheral neuropathy, or for those with prosthetic limbs. Advances in haptic technologies for stimulating the sense of touch hold the potential to aid individuals with peripheral sensory impairments, and to assist those who may have lost a limb by helping to restore touch sensation in a prosthesis. Conscious percepts of touch are enabled by receptors that translate contact-dependent mechanical and thermal stimuli into neural impulses that are transmitted through the nervous system to the brain [2]. A major outstanding challenge in haptic engineering is to reproduce touch-like stimuli via an electronic interface, and many methods for doing so are described in the literature, and are exemplified in commercial products. Despite the potential applications in sensory aids, far less attention has been devoted to the possibility of electronically processing and enhancing tactile information that is felt by the skin during natural haptic interaction. The approach described in this Work-in-Progress contribution is inspired by previous research by Yao et al., in which the authors created an instrument for surgical procedures that could amplify the vibrations felt between the instrument tip and a surface [4]. The authors demonstrated that using this handheld instrument, users were able to perceive lesions in tissue that would otherwise go unnoticed. We adopt a similar 1Electrical and Computer Engineering Department, Drexel University, PA 19104, USA [email protected] 2School of Biomedical Engineering, Drexel University, PA 19104, USA