Active lenses which darken on command
Spectacle wearers may soon be able to change their lenses from clear to dark at the flick of a switch. While traditional photochromic, or transition, lenses passively change their tint in response to light conditions, the change can take a number of seconds and may not be suitable in all conditions, such as those wearing a brimmed hat in the sunshine.
A team of researchers at the Georgia Institute of Technology in the US has reimagined transition lenses by creating a lens which uses an electrical charge to switch from light to dark in just a few seconds.
The Future of photochromatic lenses?
The lenses form part of the wider group of ‘active materials’, those which can alter their properties under certain conditions, such as when an electric charge is applied. The immediacy of the change offered by the active lenses may be more suitable for a range of professions, such as pilots or soldiers. The electrochromic polymer (ECP) lenses could be controlled by the wearer to instantly change depending on lighting conditions.
The prototype lens is brown, but the team, which created the lenses through a combination of inkjet printing and blade-coating, say any number of colours could be generated.
The authors write: “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 colourless transmissive states and coloured states that correspond to commercially available sunglasses.”
The research is published in the journal ACS Applied Materials and Interfaces.