Sensars Neuroprosthetics is pioneering a neuroprosthetic device called SENSY that restores natural sensation to amputees by directly stimulating their nerves. The company’s mission is to improve the quality of life for amputees and those with peripheral nerve damage by giving them back the feeling of their missing limb. SENSY is an implantable interface to the nervous system that can send sensory information from a prosthetic leg or arm to the user’s brain in real-time, closing the loop in limb prostheses.

The SENSY system consists of ultra-thin intraneural electrodes implanted into the remaining peripheral nerves of the amputee’s limb, a small implanted neurostimulator connected to those electrodes, and external sensors (for instance, pressure sensors on the prosthetic foot sole) plus a controller. When the user steps on an object or terrain, the sensor data are wirelessly sent to the implanted stimulator, which then delivers patterned electrical pulses to specific nerve fibers corresponding to, say, the sole of the foot. This evoked neural activity travels up the nerve to the brain, where it is perceived as if coming from the missing foot. Because SENSY’s intraneural electrodes penetrate inside the nerve, they can selectively activate different sensory fibers (e.g. those for pressure, for toe position), creating rich, specific sensations. The stimulation patterns are calibrated to each user so that, over time, the brain reinterprets these inputs as natural feelings of the prosthetic limb’s presence and movement.

The first target population is lower-limb amputees using prosthetic legs. Without feedback, such users can’t feel the ground or the limb, leading to risk of falls and a phenomenon of low embodiment (the prosthetic “not feeling like part of them”). In clinical tests on leg amputees, SENSY has reduced falls, increased confidence in walking, and even diminished phantom limb pain by providing sensory input where there was none. Users reported being able to sense obstacles, slopes, and texture differences through their bionic foot, allowing more natural gait and better balance. SensArs also envisions adapting the technology to arm amputees (feeling through a bionic hand) and to patients with nerve injuries (to restore lost sensation). Currently, SENSY has shown impressive results in initial trials with a few patients and has secured grant funding for larger studies. This “feeling prosthesis” exemplifies the promise of neurotechnology: by merging biology with electronics, SensArs can give amputees back a critical sense, thereby improving mobility, reducing pain, and increasing acceptance of prosthetic devices.