Pressure-sensitive artificial skin signals brain cells when touched

Artificial skin that sends pressure sensations directly to brain cells has been developed for the first time, bringing the eventual goal of flexible, healing and feeling artificial skin a step closer.

Developed by Zhenan Bao, professor of chemical engineering at Stanford, the skin is able to detect the level of pressure applied to it, be it a light touch or a hard press.

Bao, who has been working on the development of artificial skin for a decade, led a team of 17 researchers to create the technology, which has been detailed in an article published today in the journal Science.

“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,” she said.

Bao aims for the skin, which is designed to fit over a prosthetic limb, to eventually be able to heal, signal pain and detect touch and temperature.

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The artificial skin is made up of two layers of plastic, with the top layer providing sensing capabilities and the bottom sending the data to nerve cells as electrical signals.

The top layer’s sensing abilities are achieved by giving the plastic a waffle pattern, which makes the plastic very sensitive to pressure, and then dispersing billions of carbon nanotubes throughout it.

These nanotubes conduct electricity when squeezed together, so when pressure on the skin increases, the nanotubes are pushed closer together, and more electricity is conducted.

The second layer, which takes the form of a flexible electronic circuit, then transmits this electricity to nerve cells in pulses, allowing the level of pressure to be determined.

This is designed to mimic the way real human skin works, as our own awareness of pressure is the result of our brain interpreting short pulses of electricity in a similar manner.

The have not yet directly tested the skin by hooking it up to a human brain, however. Instead they took inspiration from a field known as optogenetics – where optics and genetics meet – to generate an artificial version of part of the human nervous system, which they signalled by transferring the electrical signals into pulses of light.

While this was an effective proof of concept, in the long run the researchers plan to use a different approach to directly stimulate human nerves with the electrical pulses. They are confident this can be achieved as other researchers have already found ways to stimulate neurons directly with such pulses.

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Images courtesy of Bao Research Group, Stanford University

There is still considerable work ahead before Bao’s dream of fully sensory artificial skin can be realised, but this work is an exceptionally important step along the way.

“We have a lot of work to take this from experimental to practical applications,” she said. “But after spending many years in this work, I now see a clear path where we can take our artificial skin.”

With just two layers in the current system, the researchers believe it will be easy to add additional sensors as they are developed.

Among those the researchers want to create are sensors to determine different textures, allowing the wearer to differentiate between fabrics, for example, and sensors to determine the temperature of an object.

Researchers discover remains of “Triassic Jaws” who dominated the seas after Earth’s most severe mass extinction event

Researchers have discovered the fossil remains of an unknown large predatory fish called Birgeria: an approximately 1.8-meter-long primitive bony fish with long jaws and sharp teeth that swallowed its prey whole.

Swiss and US researchers led by the Paleontological Institute and Museum of the University of Zurich say the Birgeria dominated the sea that once covered present-day Nevada one million years after the mass extinction.

Its period of dominance began following “the most catastrophic mass extinction on Earth”, which took place about 252 million years ago – at the boundary between the Permian and Triassic geological periods.

Image courtesy of UZH. Featured image courtesy of Nadine Bösch

Up to 90% of the marine species of that time were annihilated, and before the discovery of the Birgeria, palaeontologists had assumed that the first predators at the top of the food chain did not appear until the Middle Triassic epoch about 247 to 235 million years ago.

“The surprising find from Elko County in northeastern Nevada is one of the most completely preserved vertebrate remains from this time period ever discovered in the United States,” emphasises Carlo Romano, lead author of the study.

Although, species of Birgeria existed worldwide. The most recent discovery belongs to a previously unknown species called Birgeria Americana, and is the earliest example of a large-sized Birgeria species, about one and a half times longer than geologically older relatives.

The researchers say the discovery of Birgeria is proof that food chains recovered quicker than previously thought from Earth’s most devastating mass extinction event.

According to earlier studies, marine food chains were shortened after the mass extinction event and recovered only slowly and stepwise.

However, finds such as the newly discovered Birgeria species and the fossils of other vertebrates now show that so-called apex predators (animals at the very top of the food chain) already lived early after the mass extinction.

“The vertebrates from Nevada show that previous interpretations of past biotic crises and associated global changes were too simplistic,” said Romano.

Revolutionary DNA sunscreen gives better protection the longer its worn

Researchers have developed a ground-breaking sunscreen made of DNA that offers significant improvements over conventional versions.

Unlike current sunscreens, which need to be reapplied regularly to remain effective, the DNA sunscreen improves over time, offering greater protection the longer it is exposed to the sun.

In addition, it also keeps the skin hydrated, meaning it could also be beneficial as a treatment for wounds in extreme or adverse environments.

Developed by researchers from Binghamton University, State University of New York, the innovative sunscreen could prove essential as temperatures climb and many are increasingly at risk of conditions caused by excessive UV exposure, such as skin cancer.

“Ultraviolet (UV) light can actually damage DNA, and that’s not good for the skin,” said Guy German, assistant professor of biomedical engineering at Binghamton University.

“We thought, let’s flip it. What happens instead if we actually used DNA as a sacrificial layer? So instead of damaging DNA within the skin, we damage a layer on top of the skin.”

The DNA sunscreen has the potential to become a standard, significantly improving the safety of spending time in the sun

The research, which is published today in the journal Scientific Reports, involved the development of thin crystalline DNA films.

These films are transparent in appearance, but able to absorb UV light; when the researchers exposed the film to UV light, they found that its absorption rate improved, meaning the more UV is was exposed to, the more it absorbed.

“If you translate that, it means to me that if you use this as a topical cream or sunscreen, the longer that you stay out on the beach, the better it gets at being a sunscreen,” said German.

The film will no doubt attract the attention of sunscreen manufacturers, who will likely be keen to commercialise such a promising product. However, the researchers have not said if there is any interest as yet, and if there is any clear timeline to it becoming a commercial product.

 

The film’s properties are not just limited to sun protection, however. The DNA film can also store water at a far greater rate than conventional skin, limiting water evaporation and increasing the skin’s hydration.

As a result, the film is also being explored as a wound covering, as it would allow the wound to be protected from the sun, keep it moist – an important factor for improved healing – and allow the wound to be monitored without needing to remove the dressing.

“Not only do we think this might have applications for sunscreen and moisturizers directly, but if it’s optically transparent and prevents tissue damage from the sun and it’s good at keeping the skin hydrated, we think this might be potentially exploitable as a wound covering for extreme environments,” said German.