Stanford engineers have created a plastic skin-like material that can detect pressure and deliver a Morse code-like signal directly to a living brain cell. The work takes a big step toward adding a sense of touch to prosthetic limbs.
Stanford engineers have created a plastic “skin” that can detect how hard it is being pressed and generate an electric signal to deliver this sensory input directly to a living brain cell.
Zhenan Bao, a professor of chemical engineering at Stanford, has spent a decade trying to develop a material that mimics skin’s ability to flex and heal, while also serving as the sensor net that sends touch, temperature and pain signals to the brain. Ultimately she wants to create a flexible electronic fabric embedded with sensors that could cover a prosthetic limb and replicate some of skin’s sensory functions.
Bao’s work, reported today in Science, takes another step toward her goal by replicating one aspect of touch, the sensory mechanism that enables us to distinguish the pressure difference between a limp handshake and a firm grip.
“This is the first time a flexible, skin-like material has been able to detect pressure and also transmit a signal to a component of the nervous system,” said Bao, who led the 17-person research team responsible for the achievement.
Benjamin Tee, a recent doctoral graduate in electrical engineering; Alex Chortos, a doctoral candidate in materials science and engineering; and Andre Berndt, a postdoctoral scholar in bioengineering, were the lead authors on the Science paper.
The heart of the technique is a two-ply plastic construct: the top layer creates a sensing mechanism and the bottom layer acts as the circuit to transport electrical signals and translate them into biochemical stimuli compatible with nerve cells. The top layer in the new work featured a sensor that can detect pressure over the same range as human skin, from a light finger tap to a firm handshake.
Five years ago, Bao’s team members first described how to use plastics and rubbers as pressure sensors by measuring the natural springiness of their molecular structures. They then increased this natural pressure sensitivity by indenting a waffle pattern into the thin plastic, which further compresses the plastic’s molecular springs.
To exploit this pressure-sensing capability electronically, the team scattered billions of carbon nanotubes through the waffled plastic. Putting pressure on the plastic squeezes the nanotubes closer together and enables them to conduct electricity.
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.
The team then hooked this pressure-sensing mechanism to the second ply of their artificial skin, a flexible electronic circuit that could carry pulses of electricity to nerve cells.
Importing the signal
Bao’s team has been developing flexible electronics that can bend without breaking. For this project, team members worked with researchers from PARC, a Xerox company, which has a technology that uses an inkjet printer to deposit flexible circuits onto plastic. Covering a large surface is important to making artificial skin practical, and the PARC collaboration offered that prospect.
Finally the team had to prove that the electronic signal could be recognized by a biological neuron. It did this by adapting a technique developed by Karl Deisseroth, a fellow professor of bioengineering at Stanford who pioneered a field that combines genetics and optics, called optogenetics. Researchers bioengineer cells to make them sensitive to specific frequencies of light, then use light pulses to switch cells, or the processes being carried on inside them, on and off.
For this experiment the team members engineered a line of neurons to simulate a portion of the human nervous system. They translated the electronic pressure signals from the artificial skin into light pulses, which activated the neurons, proving that the artificial skin could generate a sensory output compatible with nerve cells.
Optogenetics was only used as an experimental proof of concept, Bao said, and other methods of stimulating nerves are likely to be used in real prosthetic devices. Bao’s team has already worked with Bianxiao Cui, an associate professor of chemistry at Stanford, to show that direct stimulation of neurons with electrical pulses is possible.
Bao’s team envisions developing different sensors to replicate, for instance, the ability to distinguish corduroy versus silk, or a cold glass of water from a hot cup of coffee. This will take time. There are six types of biological sensing mechanisms in the human hand, and the experiment described in Science reports success in just one of them.
The Latest on: Artificial skin
via Google News
The Latest on: Artificial skin
- Skin Replacement Market Size, Benefits, Advancements and Growth Opportunities 2018 to 2026on August 12, 2019 at 7:08 pm
Hence, to resolve the problem synthetic skin substitutes came into picture to treat deep skin wounds which promotes regeneration of artificial skin. These technological advancements have led to ...
- Development of flexible sensors mimicking human finger skin by DGISTon August 7, 2019 at 7:18 am
Senior Researcher Changsoon Choi's team at DGIST Department of Smart Textile Convergence Research and Dr. Sungwoo Chun at Sungkyunkwan University (SKKU) developed artificial skin tactile sensors that ...
- Artificial Tongue Able To "Taste" Differences Between Whiskies With 99 Percent Accuracyon August 7, 2019 at 4:47 am
Scientists have developed artificial skin, artificial eyes, and are even in the progress of designing an artificial "brain" (of sorts) for the US military. Meanwhile, researchers from the University ...
- Snakelike artificial skin allows this robot to slither around on its ownon July 28, 2019 at 5:00 pm
Mashable is a global, multi-platform media and entertainment company. Powered by its own proprietary technology, Mashable is the go-to source for tech, digital culture and entertainment content for ...
- Science Behind the Fiction: Are we getting closer to TNG's Data and his artificial skin?on July 24, 2019 at 10:57 am
Humankind has been trying to recreate aspects of the human body for millennia — like this artificial toe, made of wood, found with the body of an ancient Egyptian — but technology just can't compete ...
- An artificial nervous system called ACES could give robots a sense of touchon July 19, 2019 at 7:33 am
The new electronic skin system promises ultra-high responsiveness and can survive damage. The new artificial skin can pair with any sensor skin layers. The team took inspiration from human sensory ...
- Artificial skin can sense 1000 times faster than human nerveson July 17, 2019 at 11:54 am
An artificial skin that senses temperature and pressure can send signals 1000 times faster than the human nervous system. The skin could one day cover prosthetic limbs to help people use them better ...
- Injured Mars astronauts could heal themselves using artificial skin 3D printed from their own cellson July 10, 2019 at 5:45 am
Injured astronauts on their way to Mars could heal themselves by printing artificial skin and bones using their own cells, according to the European Space Agency (ESA). ESA is currently working with ...
- Regenerative Artificial Skin Market to reach 2,411.6 Million at Exponential CAGR 21.5% by 2024,Internationallyon June 24, 2019 at 5:53 am
Global Regenerative Artificial Skin Market is expected to reach 2,411.6 million in 2024, at an exponential CAGR of 21.5%. The Global Regenerative Artificial Skin Market studies the overall dynamics ...
- Artificial skin through super-sensing method and electrical impedance data from conductive fabric with aid of deep learningon June 20, 2019 at 3:02 am
Sense of touch is a major part of man’s communication with their environment. Artificial skins can help robots to have the same sense of touch, especially for their social interactions. This paper ...
via Bing News