A ROBOT HAND HELPS AMPUTEES "FEEL" AGAIN
Every day your fingers, wrists and forearms conduct the symphony of motor movements that allow you to click a mouse, type on a keyboard or swipe a screen. But what if you lost your hand? What kind of machine could restore your abilities to grip, click, tap or touch?
In a new study, a group of researchers at the University of Utah have re-engineered a prosthetic system to let a man, whose hand was amputated, feel sensations, helping him physically grasp a variety of objects, from a glass of wine to a single grape.
"A lot of people think of touch as one sense, but touch is actually composed of many different senses," says Jacob George, a researcher of the group. "There are sensors in your hand for pain, for temperature, for vibration, for pressure – and so what we’re doing is identifying each one of those little sensors."
The researchers isolated 119 "sensory perceptions" from their subject. To do so, they first implanted electrodes into the peripheral nerves on his forearm, and created with wires a kind of replacement for the lost hand. Then, they stimulated different circuits inside each electrode to understand what caused each sensory perception. These were then mapped onto the prosthetic hand to create a "really good approximation of the same information that the subject would get from the natural hand."
Humans have been using prostheses for thousands of years; most of the time, they have consisted of either solid attachments or mechanical structures. Recently, prostheses have become more and more complex, using lighter and stronger materials and incorporating microprocessors and automated control systems.
However, there was still the problem of how to bridge the sensory interruption between amputee and replacement limb. Research groups used neural interfaces to translate complex human motor control into machine movement.
To ensure that the touch sensation was coming just from the prosthesis, and that the subject’s feelings were not influenced by seeing the hand touch things, the researchers used a trick. They covered the subject’s eyes and ears and placed the bionic arm on a table a few feet away. They then asked him to judge whether various unseen objects were "soft" or "hard" by grasping them (without seeing them) with the bionic hand.
9. Complete the following sentences.
1. The researchers built a prosthetic hand, which could ........................................ ........................................
2. Touching is not a ........................................ sense.
3. Pain, temperature, vibrations and pressure are felt by a variety of ........................................ in our hands.
4. During the research, the amputated hand was replaced by ........................................ and these were connected to electrodes implanted on the peripheral nerves of the ........................................ .
5. The first prostheses were purely ........................................ .
6. The most recent prostheses incorporate ........................................ to control them automatically and are very ........................................ .
7. The biggest problem was to connect the ........................................ limb with the bionic hand.
8. To avoid the possibility that the subject was ........................................, the researchers covered the subject’s eyes.