Collaborative Research: RUI: Noninvasive, Natural and Intuitive Electrocutaneous Stimuli for Bionic Limbs

Many people with amputated arms stop using their prosthetic devices because they lack a sense of touch, making everyday tasks difficult and less fulfilling. This project aims to develop artificial touch that feels natural and is easy to use for people with bionic arms. This natural feeling will be created through pulsed electrical stimulation that mimics the natural nerve signals in the skin.

By using low-cost electrodes on the skin surface, this technology can be more easily commercialized and integrated with prosthetic arms, unlike technologies that require surgical implantation. Additionally, this project supports a collaboration between a primarily undergraduate institution and a major research university, allowing undergraduate students to engage in high-impact research to enhance their education and career opportunities while at the same time exposing graduate students to potential careers at primarily undergraduate institutions.

Noninvasive neurostimulation to restore touch often feels electrical, unnatural and unpleasant. This proposal develops novel biomimetic electrocutaneous (EC) stimulation algorithms to enhance the naturalness of sensations and improve functional performance and reduce cognitive load during closed-loop sensorimotor tasks (e.g., fragile object manipulation).

To create natural feeling sensory percepts, several obstacles unique to noninvasive EC stimuli need to be overcome. Because pulse frequencies above 50 Hz feel more natural but higher pulse frequencies are less able to convey a change in stimulus strength, frequency modulation alone reduces the range of perceived intensities. However, variations in electrical conductivity and build-up of electric charge at the electrode-skin interface can create unpleasant and painful sensations.

Therefore, this research explores novel multi-modal biomimetic stimulation paradigms designed to avoid activation of pain or itch nerve fibers while also providing a useful range of stimulation intensity. Individuals with transradial amputation will be recruited at both a primarily undergraduate institution and an R1 research university to test the biomimetic EC stimulation algorithms while controlling bionic arms with electromyographic signals.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.