Prize winning research results in neurorobotic lower limb prostheses that could yield multiple benefits for users

Stanisa Raspopovic is the 2021 grand prize winner of the Science & PINS Prize for Neuromodulation, for his work developing neurorobotic lower limb prostheses that can communicate critical sensory information back to the wearer. By providing more realistic physical feedback and helping to alleviate phantom limb pain, Raspopovic’s system led test users to report a greater sense of “embodiment,” or the feeling that a prosthetic is a true extension of the wearer’s body. This in turn resulted in faster, smoother traversing of everyday obstacles and more efficient energy use, the latter reflected directly in reduced metabolic cost and cardiovascular stress for the wearer. In recent years, there has been substantial progress in developing more sophisticated peripheral nervous system (PNS) interfaces, which connect prosthetic sensors directly to the remnant nerves in an amputee’s limb stump. Noting that much of this progress has been centered on the needs of upper limb amputees, Raspopovic recognized an unmet clinical need, as roughly four out of every five amputees worldwide have lost a lower limb. Raspopovic and his colleagues designed a “sensing leg,” imbued with sensors that can detect pressure and movement. This information is communicated to the wearer through a PNS interface, and the researchers used computational modeling to determine the optimal number of connections to implant in a targeted nerve. The sensors enabled the test users to avoid a number of obstacles when wearing special glasses to obscure their lower field of vision, and substantially enhanced their abilities to navigate stairs and sandy terrain, all while reducing their metabolic energy use. The PNS interface also includes a “neuro-pacemaker” mode that therapeutically stimulates the wearer’s remnant nerves without connecting to the prosthesis. The precise targeting of neural pathways, informed by computational modeling, enabled the implant to reproduce more naturalistic nerve inputs, leading test wearers to report a notable reduction in phantom limb pain.

Weijian Yang is the 2021 prize finalist for his essay, “Manipulating Neuronal Circuits, in Concert.”