Magnetically Induced Skin Stretch Enhances Proprioceptive Feedback in Prosthetics.

Proprioceptive feedback is essential for motor control and prosthetic embodiment, yet myoelectric prostheses lack naturalistic sensory input. Artificial skin stretch stimulation has emerged as a preferred method to convey proprioceptive cues, but current friction-based devices face limitations preventing integration into practical prostheses. This work investigates magnetically induced skin stretch as a non-invasive, potentially implantable alternative. We present MISS (Magnetically Induced Skin Stretch), a novel system that uses external coils to control magnets adhered to the skin, producing skin deformations that mimic subdermal implantation and evoke proprioceptive sensations. We conducted physical and psychophysical experiments, including Just Noticeable Difference and Point of Subjective Equality measurements. Eighteen participants, including five with transradial amputation, used the MISS device with a myoelectric prosthesis, where skin stretch was modulated in sync with prosthetic hand flexion. Results showed high object discrimination accuracy, with amputees performing comparably to non-disabled users. These findings demonstrate MISS as a promising proprioceptive feedback method, supporting its future integration into implantable systems.