Scientists develop artificial skin that can feel rain and the touch of a hand
Scientists develop artificial skin that can feel rain and
the touch of a hand
The prosthetic hand equipped with the proposed prosthetic
skin is used just like an actual hand to cuddle a baby doll. The prosthetic
skin shows soft mechanical properties, multimodal sensing capabilities, and
warmth corresponding to that of human body. / Kim et al.
There have been dramatic leaps in developing prosthetics,
but there's one attribute in particular that's been largely overlooked.
Many artificial limbs are almost as flexible as, and
function like, the real thing, and some even connect to peripheral nerves to
allow for mind control of the prosthesis.
But researchers have struggled to develop artificial skin
that acts and even feels like actual skin.
Now, an international team from South Korea and the
United States has designed what they call "smart skin" that will help
amputees feel their environment, whether that be humidity in the air, or a
warm, firm handshake.
"Previously, these robots or prosthetic arms/legs
did not have skins that enable high resolution/sensitivity sensing of pressure,
strain, temperature, humidity," Kim Dae-Hyeong, a co-author of a study on
the skin which appeared Tuesday in Nature Communications, told CBS News.
"We focused on this point by developing high density/sensitivity sensor
array that is similar with the real human skin."
The smart skin, which in photos appears to drape a
prosthetic hand like a see-through glove, is made of a soft polymer known as
elastomer, and contains pressure, temperature and humidity sensors and
stretchable electrodes that stimulate the existing nerves.
The researchers were able to demonstrate how the skin
could sense pressure from catching a ball as well as the temperature of a cup
of hot or cold water. It could tell wet from dry, and the skin's heat sensors
responded when it touched a baby doll warmed to body temperature.
The skin also features electroresistive heaters that
emulate body heat. In a handshake, or on a baby's tummy, an artificial limb
would give off a familiar warmth.
The smart skin was engineered with a durability and
flexibility that is close to natural skin. To achieve that, researchers shot
images of clenched fists and tilting wrists with a dozen motion-capture cameras
to find the places where skin gets stretched to its maximum.
"This provides the highest sensitivity allowed in
that specific location while minimizing the possibility of mechanical fractures
of sensors," Kim said.
Until now, the focus of skin on prosthetics has mostly
been limited to aesthetics and most work has been on improving the
functionality of the artificial limb. But some researchers are starting to see
a greater role for skin in terms how it can glean information from the
environment that, in turn, could lead to a better prosthetic.
Robert D. Gregg, who is developing autonomous
lower-limbed prosthetics at the University of Texas at Dallas, said he saw the
smart skin as "an important technological advancement towards this goal of
closing the feedback loop for the intuitive control of prostheses."
"Now that advanced bionic limbs are being designed
to mimic the mechanical functions of biological limbs, the big challenge is to
effectively interface these limbs with the human nervous system," Gregg
said by email.
"This requires information flow in two directions
between the human and prosthesis: control commands from the nervous system to
the prosthesis, and sensory feedback from the prosthesis to the nervous
system," he continued. "Early work in neural interfaces dealt
primarily with the former, but now people realize that sensory feedback is
needed from the artificial limb for a human to intuitively control the
limb."
Kim said his team has patented the research but that it
will be some time before the artificial skin reaches the market.
"Currently we have demonstrated our system in small
animals. But the next step is to continue the development for the advanced
version, such as a complicated array of sensors that emulate real mechano- and
thermo- sensory functions of the human," he said.
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