Scientists strike gold with E-skin
Scientists have developed a new type of flexible sensor that can sense touch, humidity and temperature simultaneously.The technology, which was created by a team at the Technion-Israel Institute of Technology using small particles of gold and a type of resin, could have major implication in the field of robotics by helping machines better interact with humans and register changes in their environment.
Research team leader Professor Hossam Haick said the sensor is at least 10 times more sensitive than other touch-based E-skin designs currently in existence.
The team worked within certain parameters to try and ensure the development would be easily adaptable for practical everyday use. This included making sure it could run on low voltage so would be compatible with batteries that are currently on the market.
They also wanted to ensure it could measure a wide range of pressures and measure more than one aspect at a time including humidity, temperature, pressure, and to indicate whether chemicals are present.
Finally, for potential mass production, the sensors would have to be able to be produced simply, quickly and at a low cost.
The sensor is made through the use of monolayer-capped nanoparticles that are only 5-8 nanometers in diameter. They are made of gold and surrounded by connector molecules called ligands.
Haick explained: “The monolayer-capped nanoparticles can be thought of as flowers, where the center of the flower is the gold or metal nanoparticle and the petals are the monolayer of organic ligands that generally protect it.”
The nanoparticles were laid on top of a substrate, in this case the same type of plastic found in drink bottles. The team found that the resulting compound conducted electricity differently depending on how the substrate was bent, with the bending motion bringing some particles closer to others, increasing how quickly electrons can pass between them.
This electrical property means that the sensor can detect a large range of pressures, from tens of milligrams to tens of grams. By varying how thick the substrate is and what it is made of scientists can modify how sensitive the unit is.