Most of us take the the subtle difference between rough and smooth beneath our fingertips for granted. But a new device could allow amputees to rediscover the same sensation.
Developed by researchers from Ecole polytechnique fédérale de Lausanne, the device uses a series of sensors to detect undulations in the surface beneath them, converting the physical feel into electric signals. These signals can then be injected into the nerves of a patient.
Dennis Aabo Sørensen is an amputee who had the device attached to the nerves located above his stump. He explains what he felt to TechXplore:
The stimulation felt almost like what I would feel with my hand. I still feel my missing hand, it is always clenched in a fist. I felt the texture sensations at the tip of the index finger of my phantom hand.
In a series of tests, Sørensen could differentiate between rough and smooth textured plastic samples 96 percent of the time.
In another series of experiments, the device was used to inject signals into the median nerve of non-amputees, too. These participants were able to distinguish between smooth and rough 77 percent of the time. A series of EEG measurements of brain signals revealed that the sensation from the prosthetic device and real finger were broadly similar. The results are published in eLife.
The device clearly promises to bring feeling to amputees, but it could also find application in robotics, allowing automatons to detect textures with greater accuracy.