A new research found that a graphene-based light detector can sense a full infrared spectrum and has the potential to place heat vision technology into contact lenses.
Graphene is scientifically proven to sense full infrared spectrum and visible and ultraviolet (UV) light. However, it hasn't been found to detect infrared alone as the latter can't capture enough light to produce a measurable electric signal.
Infrared can only absorb about 2.3 percent of light that hits it -- an amount not enough to make electric signals.
To increase sensitivity of graphene-based detectors, engineer researchers from the University of Michigan created a new way to make infrared generate electric signals. With their new creation, instead of directly measuring the electrons released as light hits the graphene, they increased the electric signal by looking at how the graphene light-induced electrical charges affect a close by current.
After that, they devised the sensor by placing an insulating barrier layer amid two horizontally lying graphene sheets. When the light from the current running through the bottom layer hits the top layer, it will free electrons, thus producing positively charged electrons. The electrons will then use a quantum mechanical trick to pass through the insulating barrier into the graphene sheet below, thus allowing the sensitivity of a graphene devise to compete with cooled mid-infrared detectors.
Through the measurement of the change in the current, the team could infer the brightness of the light hitting the graphene.
If the process will be incorporated in contact lenses or other wearable devices, the vision of the user will expand.
"Our work pioneered a new way to detect light," said Zhaohui Zhong, assistant professor of electrical engineering and computer science in the University of Michigan, in a university news release. "We envision that people will be able to adopt this same mechanism in other material and device platforms."
Further details on the study can be read in the March 16 issue of the Nature Nanotechnology.
