Digital Extensions with Bi-axial Fingertip Sensors for Supplementary Tactile Feedback Studies

Using a hand prosthesis means grasping without tactile information. Although supplementary sensory feedback has been investigated extensively, few study results could translate into clinical applications. Unreliable and imprecise feedforward control of current hand prostheses hinders the investigation of supplementary sensory feedback, so an ideal feedforward tool should be used. Thus, we aimed to create a device that would allow to use the sensory deprived human hand as an ideal tool without the need for local anesthesia. For this, we fashioned silicone digit extensions with integrated force sensors and tested the performance of 12 volunteers in grasping with these extensions. Two tests were performed: a simple pick and lift test to compare performance to anesthetized digits, and a virtual egg test to assess grasping efficiency. We found that the extensions significantly alter grasping. In future studies, these extensions will help us investigate how to artificially restore the information necessary for successful and efficient grasping with an ideal feedforward tool.