Scientists have made a surprising discovery. A temperature experiment led to a breakthrough in bionics. Future innovations could provide a more natural sense of touch for people who have lost limbs.
God gave humans five senses. For most people, hands are the main collectors of touch information. They help one interact with the world. Haptics is the science of the sense of touch. Now for those who have lost limbs, scientists who study haptics are working to devise options.
Researchers Silvestro Micera and Solaiman Shokur study haptics with artificial limbs, or prosthetics. Their work focuses on giving prosthetics sensory feedback. One recent study dealt with temperature.
Using electrodes, researchers applied heat or cold to a device located on 27 amputees’ residual arms. They hoped electrodes would allow subjects to feel temperature differences on their arms.
What happened next surprised them.
“We were expecting for them to tell us, with eyes closed, where they felt it on the stump and if it was hot or cold,” Shokur says. “Instead, they pointed into a drawing of a hand that they had in front of them, and they told us, ‘I feel it there.’”
Turns out, 17 amputees sensed temperature not only on a residual limb but also in a missing hand. Shokur calls it the “thermal phantom sensation.”
For testing, Micera and Shokur used a thin, wearable sensor called MiniTouch. An amputee places it on a prosthetic finger. The sensor detects temperature information about any touched object. A thermode on the skin of the residual arm relays information about the object.
Using MiniTouch, someone with a prosthetic hand can tell differences in temperature and even in materials like glass, plastic, metal—and the sensation feels as though it is coming through the prosthetic.
Study participant Fabrizio Fidati is missing his right hand. Yet during the test, he felt warmth on his phantom index finger. He calls warmth “the most beautiful feeling there is.”
Francesca Rossi is also missing a hand. She too felt warmth in her missing hand during the study. But she sensed more than temperature. She says her hand “does not feel phantom anymore.”
Thermal phantom sensation and related technologies create new possibilities for prosthetics wearers. Because MiniTouch does not require a direct connection to the body’s nervous system, it is easier and safer to use. Further, it allows the amputee to feel connected to a prosthesis as an actual body part, instead of just a “tool.”
“Temperature feedback is essential for relaying information that goes beyond touch. It leads to feelings of affection,” says Micera. “We are social beings, and warmth is an important part of that.”
Why? There is still much to be learned about our marvelous, God-created bodies, but God mercifully allows for technology and scientific study to address and in many cases restore function after injury or disease.
