Graphene Allows Your Contact Lenses To See Infrared Images

It sounds like an espionage thriller, and you can see infrared images as long as you put on a pair of contact lenses. Researchers at the University of Michigan turned their glasses into a reality, using graphene to develop fingernails-sized infrared image sensors without the need for bulky cooling devices. Because of its small size, light weight, it can be integrated into contact lenses or mobile phones, in the military, security, medicine and other fields have a wide range of applications.

The study was published in the journal Nature Nanotechnology. Infrared wavelength between 760 nm to 1 mm, is the wavelength than red light of the longer than visible, divided into near infrared, medium infrared and far infrared three kinds. Both the IR and the far infrared sensors usually have to work at very low temperatures. Chong (Zhaohui Zhong), assistant professor of electrical engineering and computer science at the University of Michigan, and his team improved the process of producing electrical signals from graphene, setting up an insulating layer between two graphene flakes with an electric current through.

When the light hits the top graphene, the device releases electrons and creates a positively charged hole. Then, under the quantum tunneling effect, electrons pass through the middle insulating layer and reach the bottom of the graphene layer. At this point, the positively charged holes remaining on the upper graphene will produce an electric field and affect the current of the lower graphene. By measuring the change of the current, the brightness of the light irradiated on the upper graphene can be inferred. Chong said the new method first allowed the sensitivity of both the IR and far-infrared sensors to a new height that could be comparable to a traditional infrared sensor that required a cooling device to run.