A 57-year-old man with a prosthetic limb has felt warmth and cold in his phantom hand — thanks to a new technology called MiniTouch.
This bionic technology enables individuals with prosthetic limbs not just to sense but to actively respond to subtle temperature changes.
The MinTouch technology does this by seamlessly transferring "thermal information" from the artificial hand's fingers to the amputee's residual limb.
The researchers at Ecole Polytechnique Federale de Lausanne believe that this sensory input will improve amputees' capacity to explore and interact with their environment more safely.
“Adding temperature information makes the touch more human-like. We think having the ability to sense temperature will improve amputees’ embodiment—the feeling that ‘this hand is mine,’” said Solaiman Shokur, senior author, in the press release.
Identifying various temperatures
Recognizing sensations like as pressure, pain, vibration, and temperature is critical for interacting safely and efficiently with our surroundings.
As a result, it is critical to create technologies that can restore sensation to those who have had their hands amputated or who wear prosthetics.
This non-invasive technology can be simply fitted into amputees' prosthetic limbs.
As per the press release, it operates by providing “active thermosensation” during activities that require feedback between sensory and motor neurons.
In the conducted tests, researchers integrated this new bionic device into the prosthetic limb of a man who had undergone a trans-radial amputation 37 years ago.
The device was strategically connected to a point on the participant's residual limb that triggered thermal sensations in his phantom index finger.
The researchers next assessed the man's ability to distinguish between objects of varying temperatures and materials. Remarkably, with the assistance of MiniTouch, the participant displayed the ability to discern different temperatures effectively.
During one test scenario, the man was able to identify bottles containing water at different temperatures (cold at 12°C, cool at 24°C, and hot at 40°C). The results were striking: with the aid of MiniTouch, the participant achieved 100% accuracy in distinguishing between the temperatures, compared to 33% without the device.
Feeling human touch using the new device
In addition, the participant demonstrated the capability to categorize metal cubes based on their temperatures and identify the sensation of human touch.
When using the gadget, he was able to discern between human and artificial limbs even while blindfolded, achieving an impressive accuracy rate of 80%.
The release highlights that the device still has some limitations in terms of human touch when compared to his uninjured arm.
The researchers think that this restriction may be linked to limits in other non-thermal sensory inputs, such as the prosthesis's inability to relay information regarding skin softness and texture.
“Our goal now is to develop a multimodal system that integrates touch, proprioception, and temperature sensations. With that type of system, people will be able to tell you ‘this is soft and hot,’ or ‘this is hard and cold,’” said Shokur in the press release.
The findings were published in the journal Med.
