In research that brings science one step closer to adding a sense of touch to prosthetic limbs, a team of engineers from Stanford University have developed a plastic skin-like material capable of detecting pressure and delivering an electric signal to living brain cells.
The discovery, which was detailed in the October 16 edition of the journal Science, marks the first time that “a flexible, skin-like material has been able to detect pressure and also transmit a signal to a component of the nervous system,” lead author Zhenan Bao, a chemical engineering professor at the California-based school, said earlier this week in a statement.
For a decade, Bao and her colleagues have been attempting to fabricate a material which could mimic the skin’s ability to flex and heal, as well as sending touch, pain and temperature signals to the brain. The ultimate goal, the university said, is to create an electronic fabric that could be place over a prosthetic limb and simulate the sensory functions of actual human skin.
With the publication of this new paper, she revealed that her team is one step closer to achieving that goal, as their new skin-inspired organic digital mechanoreceptor can distinguish between the respective pressures of a limp handshake and a firm grip and communicate that to the brain.
Using optogenetics to prove compatibility with neurons
The device consists of a two-ply plastic construct, Bao and her colleagues said. The upper layer creates a sensing mechanism, which the lower layer acts as the circuit, transporting the electrical signals and converting them into biochemical stimuli so they can be detected by nerve cells. The top layer uses sensors that can purportedly detect the same pressure ranges as real skin.
To prove that the electronic signal could be identified by a biological neuron, they used a method known as optogenetics that combines the fields of optics and genetics. They bioengineered a line of neurons designed to simulate part of the human nervous system and translated pressure signals given off by the artificial skin from electronic to neuron-activating pulses of light.
While this proved that the artificial skin was able to generate a sensory output compatible with nerve cells, Bao said that it was used only as an experimental proof of concept. Her team is now working on other ways to simulate nerves for use in actual prosthetic devices, but she admits that they have “a lot of work to do to take this from experimental to practical applications.”
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Feature Image: Stanford chemical engineering Professor Zhenan Bao and her team have created a skin-like material that can tell the difference between a soft touch and a firm handshake. The device on the golden fingertip is the skin-like sensor developed by Stanford engineers. (Credit: Bao Lab)
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