Saturday, March 17, 2018 by David Williams
Graphene has a number of unique and fairly interesting properties, among which is its ability to turn heat into electricity. Now a group of researchers led by Grigory Skoblin of Chalmers University of Technology in Sweden has taken this thermoelectric property and turned it into the driving force behind a new type of radiation detector.
The researchers developed a device called a bolometer, and they detailed the challenges they met as well as the advantages that the new device offers in a new study titled, “A new radiation detector made from graphene.” Its subheading reads, “A new bolometer exploits the thermoelectric properties of graphene.” The details of their research appeared recently in the journal Applied Physics Letters, from AIP Publishing.
Graphene was first discovered more than 10 years ago and was thought of as a possible miracle material due to its interesting physical or material properties. “But unfortunately, there are some strong fundamental limitations for this material,” said Skoblin. “Nowadays, the real industrial applications of graphene are quite limited.”
Graphene gets most of its useful properties from its material construction. Being composed of only single sheets of carbon makes it versatile enough to be used for various purposes. By exploiting this property, they were able to develop their own special type of bolometer.
Standard radiation can heat part of the device and cause electrons in it to move. This, in turn, causes displaced electrons to generate their own electric field, which results in the creation of a voltage difference across the device. The resulting change in voltage is used as a way of detecting or measuring levels of radiation directly. Compared with other devices which take incoming radiation and generate electric currents or resistance changes, this was far simpler. Older versions of this same device, which featured a double layer of graphene, were also not as effective and much harder to scale. The researchers found that the single-layer version was much more efficient. (Related: 10 natural remedies for radiation exposure.)
The device created by the researchers also offers one other advantage. It has a special coating called Parylene, a dielectric polymer, that gives it a good balance of performance and scalability, according to the researchers. According to Skoblin, you can get better performance by coating with hexagonal boron nitride, but it’s hard to acquire and there are no easy ways to scale up the coating techniques necessary for its use. It’s also said that other studies show how inefficient a bolometer would be if they go down the route of the hexagonal boron nitride coating, so the researchers opted to simply ignore it.
So far, the researchers have tested their prototype device with microwave radiation, specifically at 94 gigahertz, but they are looking at widening the frequency range in future designs. Their next plan involves trying to build their device with the use of chemical vapor deposition, which would allow them to grow much larger pieces of graphene. If they can succeed in doing that, it might just be the breakthrough that’s needed to take this idea and raise it up to the level of mass production.
Read more the harmful effects of radiation in Radiation.news.