Validation and Verification of a Haptic Interface for Body-Powered Partial Hand Prostheses

Purely mechanically driven haptic feedback systems utilise hydro-mechanical forces applied to a fingertip sensor to increase internal fluid pressure, activating the membrane of a feedback actuator and generating tactile sensations. This paper presents the design, fabrication, as well as verification, and validation of an integrated haptic feedback system in a body-powered partial hand prosthesis. We implemented the mechano-tactile haptic feedback mechanism in a Naked Prosthetics device, specially fabricated for a patient with small finger and ring finger amputations. Verification experiments were conducted to characterise the physical interaction between the custom-designed fingertips and the soft membrane of the feedback actuators. We also validated the haptic feedback system in a clinical trial setting with an amputee, demonstrating its practical application and effectiveness. The evaluation included objective performance metrics, such as task completion time, alongside subjective assessments of the tactile haptic feedback experienced by the user. The results demonstrate that the integration of mechano-tactile feedback into the body-powered prosthesis was perceptible to the user and moderately improved the time required to complete daily tasks.