A person who has amputated his right arm shows where on his phantom hand he senses a certain temperature.
Alan Herzog
Amputees can make their phantom hands feel changes in temperature and matter, and the discovery could help give prostheses a higher sense of touch.
After amputation, some people experience the feeling that the missing arm or leg is still attached, known as a phantom limb. To learn more about these limbs, Solaiman Chocour and colleagues at the Swiss Federal Institute of Technology in Lausanne studied 26 people who had lost at least part of one arm in an accident and reported experiencing a phantom hand.
The researchers attached devices to the participants’ stumps that could change the temperature. Then, applying her three temperatures of 25°C (77°F), 32°C (89.6°F), and 37°C (98.6°F), the participant felt warm in her phantom hand. They reported whether they could feel heat and whether they could feel warmth. , if the temperature can be distinguished.
Seventeen said they felt a phantom change in the temperature of their hands when using the device, which the researchers called a phantom heat sensation. Of these, 15 were able to distinguish between her three temperatures. “Our hypothesis is that the nerve continues to grow within the skin after amputation,” Shokur said. “By precisely targeting those nerves, we create this phantom sensation.”
It is unclear why only 17 of the participants reported feeling the temperature. “What we’ve found is that many of the people who didn’t respond had a fire-related accident that resulted in skin burns and probably a lot of skin loss,” he said. he says
In another part of the experiment, researchers applied sensors to three materials: glass, copper, and plastic. The sensor was attached to the residual arm of nine blindfolded participants with phantom heat sensations. It was initially set to his 32°C, the approximate temperature of skin, and then cooled at about the same rate as the skin temperature of a hand when touching copper, glass, or plastic.
Participants identified which material the sensor was touching with a success rate of 66 percent. On the other hand, the success rate for touching the material with an intact hand was 67 percent.
The researchers hope to develop sensors that can be applied to the fingertips of prosthetic hands, allowing people with amputated arms or hands to detect temperature. Not only does this help prevent burns in amputees, but it also makes contact feel more natural, Shokur said. “One said he wanted to feel the warmth of a child by wearing the device while holding his child’s hand,” he says.
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