A hand without a sense of touch doesn’t really feel like a hand, many amputees describe. It’s more like a pliers that can be manipulated by sending signals from the brain to the prosthetic device. They dream of being able to delicately pick up a glass or to feel the touch of a loved one’s hand.
Stanford chemical engineering professor Zhenan Bao, PhD, and her team have spent a decade trying to help make this dream a reality, by developing a material that mimics skin and its sensory functions. Taking a big step towards this goal, they have now created a skin-like material that can tell the difference between a soft touch and a firm handshake.
Their artificial skin has two layers. The bottom layer acts as a circuit that transports pulses of electricity to nerve cells and translates these signals into biochemical stimuli that the nerve cells can detect. The top layer is a sensing mechanism composed of thin plastic embedded with billions of carbon nanotubes. When pressure is put on the plastic, the nanotubes are squeezed closer together enabling them to conduct electricity. What’s new is that the top layer can now detect pressure over the same range as human skin.
According to a Stanford news release:
This allowed the plastic sensor to mimic human skin, which transmits pressure information to the brain as short pulses of electricity, similar to Morse code. Increasing pressure on the waffled nanotubes squeezes them even closer together, allowing more electricity to flow through the sensor, and those varied impulses are sent as short pulses to the sensing mechanism. Remove pressure, and the flow of pulses relaxes, indicating light touch. Remove all pressure and the pulses cease entirely.
A paper describing Bao’s new research has just been published in Science. As Bao comments in the release, "We have a lot of work to take this from experimental to practical applications. But after spending many years in this work, I now see a clear path where we can take our artificial skin."
Jennifer Huber, PhD, is a science writer with extensive technical communications experience as an academic research scientist, freelance science journalist, and writing instructor.
Previously: Stanford researchers develop transparent, stretchable skin-like sensor, Stretchable solar cells could power electronic ‘super skin’ and Neuroscientists dream big, come up with ideas for prosthetics, mental health, stroke and more
Photo by Bao Lab