Graphene is a genuine wonder invention, a material with individual layers just one atom thick that has
seemingly endless uses. Developed at the University of Manchester and winning the Nobel Prize in Physics in 2010, it has been used in the development of very strong, flexible, lightweight displays screens and armor plating, durable, highly-conductive solar cells, and even microscopic drug delivery systems. Now, a new study published in the journal Nano Letters reveals that graphene can also be used to create next-generation night vision contact lenses that also pick up on heat signatures.
Contemporary night vision (NV) technology amplifies the small amounts of visible light present in dark environments. The infrared segment of the electromagnetic spectrum is also picked up on by NV scanners or goggles; this effectively registers thermal signatures of living and non-living things.
The benefit of the thermal vision is that it can be used to see through dusty particles, for example in a smoke-filled or misty environment. However, current technology means that these systems require cooling to extremely low temperatures in order to operate effectively – it’s required to filter out the background thermal radiation in order to create a reliable image.
The cryogenic cooling systems used often mean that the NV devices are bulky, less portable and far more expensive to operate; they are certainly far less practical when used in fast-moving military situations. Another limitation with the current technology is that it’s difficult to scan for the entire range of the thermal spectrum – near-, mid- and far-infrared radiation scanners all require different sensors.
Image credit: Contemporary night vision goggles in action. Program Executive Office Soldier/Flickr; CC-BY-2.0
This is where graphene comes in. The research team, led by the Massachusetts Institute of Technology (MIT), integrated a two-dimensional graphene layer with a silicon microelectromechanical system (MEMS), a type of miniature device that can perform incredibly complex functions, including registering minute changes in temperature, pressure, magnetic field strength and radiation.
Graphene is an ultra-flexible, durable, transparent material. It’s also highly efficient at conducting electricity and is sensitive to the entire infrared spectrum, as well as visible and ultraviolet light – making it somewhat similar to the NV technology used by the fearsome alien Predator in the eponymous 1987 movie.
This sensitivity to multiple types of radiation means that these new graphene NV lenses do not require the use of a bulky, time-limited, expensive cryogenic cooling system. As graphene is also ultra-thin, it means that these devices could theoretically be worn as contact lenses.
A team of scientists at the University of Michigan also created a graphene-based fingernail-sized device last year that performs the same function: it can detect infrared radiation at room temperature, again not requiring cooling. Being so small, the graphene can only absorb a very small fraction of the incoming radiation – perhaps as low as 2.3%.
However, those researchers took advantage of the “quantum tunneling effect,” where electrons freed by the radiation hitting the lens force their way through the central insulating layer despite not being particularly energetic. This allowed the incoming radiation signal to be amplified, making the device more sensitive than it otherwise would be.
With both studies showing how effective incredibly small, incredibly sensitive graphene-based NV devices can be, it might not be long before the technology is mass produced, bringing another sci-fi concept into the real world.
iflscience