The idea of transitional lenses - that can be clear or shaded depending on the intensity of surrounding light - is a useful one, but many users find they do not suit their needs. Now, scientists are working on a lens material that can change from clear to shaded and back again in seconds - when the user commands it.
The new eyeglass material is being developed by a team led by John Reynolds, professor of chemistry & biochemistry, materials science & engineering at the Georgia Institute of Technology in Atlanta.
The team is working on the new material in collaboration with the German technology company BASF.
The material changes color, from clear to shaded, in response to a change in electrical charge, which the team says could be controlled by the user - for instance, by means of a switch.
They report their progress so far in the journal ACS Applied Materials & Interfaces.
The researchers say many of the transitional lenses currently available - which change in response to the brightness of surrounding light - do not always perform in the way users want them to.
For example, they do not block out very harsh light, such as that from snow, or the glare from strip-lighting in grocery stores.
Also, the transition time from clear to color can take several minutes with current lenses. This can be annoying - and potentially hazardous - for people who need a much faster response.
The team believes their new, fast-changing material could be very useful for airline pilots and security guards.
Another common dissatisfaction with current transition lenses is they do not always change when you need them to. For example, if you are wearing a baseball cap or driving a car, the lenses stay clear, even in bright sunlight.
New lens material changes from shaded to clear in seconds
The new lens material the team has created is a blend of electrochromic polymers (ECPs) that they say can be incorporated as the active material in user-controlled electrochromic eyewear.
The authors note how, through "predictive color mixing" of ECPs in a "subtractive fashion," they created various hues of brown by mixing "cyan and yellow primaries in combination with orange and periwinkle-blue secondary colors."
In lab tests, all the color blends showed an ability to change from shaded (10% transmittance of light) to clear (70% transmittance) in a few seconds.
To make the lenses, the team used a combination of inkjet printing and blade-coating, a process they say can easily be scaled up for manufacturing. They also say it is possible to match the full range of hues available in commercial sunglasses:
"We demonstrate the attractiveness of these ECP blends as active materials in electrochromic eyewear by assembling user-controlled, high-contrast, fast-switching and fully solution-processable electrochromic lenses with colorless transmissive states and colored states that correspond to commercially available sunglasses."
In December 2014, Medical News Today learned about another group of scientists that is developing a groundbreaking wireless material that could one day restore sight to damaged retinas.
In the journal Nano Letters, they describe how the material they are working on activates brain neurons in response to light without the use of wires to an external source of energy or light.