CLs measure blood sugar

US scientists have developed colour-changing contact lenses to test the blood sugar levels of diabetes patients.

Researchers at the University of Akron, Ohio, said the contact lenses sensed levels of sugar in tears and changed colour accordingly.

Dr Jun Hu, associate professor of chemistry at the University of Akron, explained: 'The pH paper changes colour depending on the acidity or the proton concentration of the liquid applied. That is similar to what happens in our specially designed contact lens. The sugar molecule acts like the proton in a pH test, displacing a colour dye embedded in the lens, and the lens changes colour.'