Nanotechnology Now







Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Touch-sensitive plastic skin heals itself

A researcher slices the self-healing skin with a scalpel. Photo: Linda A. Cicero, Stanford News Service
A researcher slices the self-healing skin with a scalpel. Photo: Linda A. Cicero, Stanford News Service

Abstract:
Nobody knows the remarkable properties of human skin like the researchers struggling to emulate it. Not only is our skin sensitive, sending the brain precise information about pressure and temperature, but it also heals efficiently to preserve a protective barrier against the world. Combining these two features in a single synthetic material presented an exciting challenge for Stanford Chemical Engineering Professor Zhenan Bao and her team.

Touch-sensitive plastic skin heals itself

Stanford, CA | Posted on November 11th, 2012

Now, they have succeeded in making the first material that can both sense subtle pressure and heal itself when torn or cut. Their findings will be published on November 11 in the journal Nature Nanotechnology.

In the last decade, there have been major advances in synthetic skin, said Bao, the study's principal investigator, but even the most effective self-healing materials had major drawbacks. Some had to be exposed to high temperatures, making them impractical for day-to-day use. Others could heal at room temperature, but repairing a cut changed their mechanical or chemical structure, so they could only heal themselves once. Most importantly, no self-healing material was a good bulk conductor of electricity, a crucial property.

"To interface this kind of material with the digital world, ideally you want them to be conductive," said Benjamin Chee-Keong Tee, first author of the paper.

A NEW RECIPE

The researchers succeeded by combining two ingredients to get what Bao calls "the best of both worlds" - the self-healing ability of a plastic polymer and the conductivity of a metal.

They started with a plastic consisting of long chains of molecules joined by hydrogen bonds - the relatively weak attractions between the positively charged region of one atom and the negatively charged region of the next.

"These dynamic bonds allow the material to self-heal," said Chao Wang, a co-first author of the research. The molecules easily break apart, but then when they reconnect, the bonds reorganize themselves and restore the structure of the material after it gets damaged, he said. The result is a bendable material, which even at room temperature feels a bit like saltwater taffy left in the fridge.

To this resilient polymer, the researchers added tiny particles of nickel, which increased its mechanical strength. The nanoscale surfaces of the nickel particles are rough, which proved important in making the material conductive. Tee compared these surface features to "mini-machetes," with each jutting edge concentrating an electrical field and making it easier for current to flow from one particle to the next.

The result was a polymer with uncommon characteristics. "Most plastics are good insulators, but this is an excellent conductor," Bao said.

BOUNCING BACK

The next step was to see how well the material could restore both its mechanical strength and its electrical conductivity after damage.

The researchers took a thin strip of the material and cut it in half with a scalpel. After gently pressing the pieces together for a few seconds, they found the material gained back 75 percent of its original strength and electrical conductivity. The material was restored close to 100 percent in about 30 minutes. "Even human skin takes days to heal. So I think this is quite cool," said Tee.

What's more, the same sample could be cut repeatedly in the same place. After 50 cuts and repairs, a sample withstood bending and stretching just like the original.

The composite nature of the material created a new engineering challenge for the team. Bao and her co-authors found that although nickel was key to making the material strong and conductive, it also got in the way of the healing process, preventing the hydrogen bonds from reconnecting as well as they should.

For future generations of the material, Bao said the team might adjust the size and shape of the nanoparticles, or even the chemical properties of the polymer, to get around this trade-off.

Nonetheless, Wang said the extent of these self-healing properties was truly surprising: "Before our work, it was very hard to imagine that this kind of flexible, conductive material could also be self-healing."

SENSITIVE TO THE TOUCH

The team also explored how to use the material as a sensor. For the electrons that make up an electrical current, trying to pass through this material is like trying to cross a stream by hopping from stone to stone. The stones in this analogy are the nickel particles, and the distance separating them determines how much energy an electron will need to free itself from one stone and move to another.

Twisting or putting pressure on the synthetic skin changes the distance between the nickel particles and, therefore, the ease with which electrons can move. These subtle changes in electrical resistance can be translated into information about pressure and tension on the skin.

Tee says that the material is sensitive enough to detect the pressure of a handshake. It might, therefore, be ideal for use in prosthetics, Bao added. The material is sensitive not only to downward pressure but also to flexion, so a prosthetic limb might someday be able to register the degree of bend in a joint.

Tee pointed out other commercial possibilities. Electrical devices and wires coated in this material could repair themselves and get electricity flowing again without costly and difficult maintenance, particularly in hard-to-reach places, such as inside building walls or vehicles.

Next up, Bao said the team's goal is to make the material stretchy and transparent, so that it might be suitable for wrapping and overlaying electronic devices or display screens.

Ranulfo Allen, a graduate chemical engineering student, also contributed to this research.

The research was supported by the Air Force Office of Scientific Research (AFOSR).

This article was written by Kelly Servick, a science-writing intern working for the Stanford University School of Engineering.

####

For more information, please click here

Contacts:
Andrew Myers

650-736-2245

Copyright © Stanford School of Engineering

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Quantum teleportation on a chip: A significant step towards ultra-high speed quantum computers April 1st, 2015

So, near and yet so far: Stable HGNs for Raman April 1st, 2015

Two-dimensional dirac materials: Structure, properties, and rarity April 1st, 2015

3-D neural structure guided with biocompatible nanofiber scaffolds and hydrogels April 1st, 2015

Display technology/LEDs/SS Lighting/OLEDs

Roll up your screen and stow it away? Tel Aviv University researchers develop molecular backbone of super-slim, bendable digital displays March 30th, 2015

Solving molybdenum disulfide's 'thin' problem: Research team increases material's light emission by twelve times March 29th, 2015

Haydale Announce Dedicated Graphene Inks Manufacturing Capability March 25th, 2015

Caltech scientists develop cool process to make better graphene March 18th, 2015

Govt.-Legislation/Regulation/Funding/Policy

Two-dimensional dirac materials: Structure, properties, and rarity April 1st, 2015

Rutgers, NIST physicists report technology with potential for sub-micron optical switches March 31st, 2015

SUNY Poly CNSE and Title Sponsor SEFCU Name Capital Region Teams Advancing to the Final Round of the 2015 New York Business Plan Competition March 30th, 2015

Princess Margaret scientists convert microbubbles to nanoparticles: Harnessing light to advance tumor imaging, provide platform for targeted treatment March 30th, 2015

Nanomedicine

3-D neural structure guided with biocompatible nanofiber scaffolds and hydrogels April 1st, 2015

Nanion Technologies Appoints James Costantin as Director of Customer Relations: Nanion is pleased to announce the appointment of Dr. James Costantin as Director of Customer Relations at Nanion Technologies Inc. March 31st, 2015

Nanomedicine shines light on combined force of nanomedicine and regenerative medicine March 31st, 2015

Prototype 'nanoneedles' generate new blood vessels in mice: Scientists have developed tiny 'nanoneedles' that have successfully prompted parts of the body to generate new blood vessels, in a trial in mice March 31st, 2015

Materials/Metamaterials

Wrapping carbon nanotubes in polymers enhances their performance: Scientists at Japan's Kyushu University say polymer-wrapped carbon nanotubes hold much promise in biotechnology and energy applications March 30th, 2015

DFG to Establish One Clinical Research Unit and Five Research Units: New Projects to Investigate Complications in Pregnancy, Particle Physics, Nanoparticles, Implants and Transport Planning / Approximately 13 Million Euros in Funding for an Initial Three-Year Period March 28th, 2015

Chemists make new silicon-based nanomaterials March 27th, 2015

UT Dallas engineers twist nanofibers to create structures tougher than bulletproof vests March 27th, 2015

Announcements

Quantum teleportation on a chip: A significant step towards ultra-high speed quantum computers April 1st, 2015

So, near and yet so far: Stable HGNs for Raman April 1st, 2015

Two-dimensional dirac materials: Structure, properties, and rarity April 1st, 2015

3-D neural structure guided with biocompatible nanofiber scaffolds and hydrogels April 1st, 2015

Military

Nanoscale worms provide new route to nano-necklace structures March 29th, 2015

UT Dallas engineers twist nanofibers to create structures tougher than bulletproof vests March 27th, 2015

Novel nanoparticle therapy promotes wound healing March 27th, 2015

Thousands of atoms entangled with a single photon: Result could make atomic clocks more accurate March 26th, 2015

Automotive/Transportation

Clean energy future: New cheap and efficient electrode for splitting water March 18th, 2015

Imperfect graphene opens door to better fuel cells: Membrane could lead to fast-charging batteries for transportation March 18th, 2015

Researchers synthesize new thin-film material for use in fuel cells: Article in the journal APL Materials shows how to grow Bi2Pt2O7 pyrochlore, potentially a more effective cathode for future fuel cells March 10th, 2015

Glass coating improves battery performance: To improve lithium-sulfur batteries, researchers added glass cage-like coating and graphene oxide March 2nd, 2015

Construction

Effect of Carbon Nanotubes on Properties of Cement Composites Studied in Iran March 23rd, 2015

Engineers create chameleon-like artificial 'skin' that shifts color on demand March 12th, 2015

Nanoparticles Increase Durability of Concrete Decorations in Cold Areas January 26th, 2015

Transparent artificial nacre: A brick wall at the nanoscale January 22nd, 2015

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More










ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2015 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE