Researchers led by Jihun Park, a materials scientist at the Ulsan National Institute of Science and Technology in South Korea, have developed a soft, flexible contact lens that monitors glucose levels in tears and tells the wearer if they are hyperglycemic. Previous studies have shown that the sugar content of tears corresponds closely with blood sugar levels. People with diabetes can monitor their sugar levels by pricking their finger and testing their blood with a glucose meter, but many find this painful and inconvenient. Park’s team hopes that the lenses will eventually be able to provide real-time, noninvasive medical diagnostics.
The contacts have glucose sensors, wireless power transfer circuits, and display pixels to visualize sensing signals in real time, which are fully integrated using transparent and stretchable nanostructures. The researchers constructed the contact lenses by using flexible, transparent components whenever possible. Only a few parts of the lens are not flexible, such as the glucose sensor, which is made from a rigid silicon pad. The components in the lens are 1/100 the thickness of the lens itself, and those that are visible to the eye are placed in sections over the iris where they cannot be seen by the wearer.
Tests were conducted on rabbits, and the results published in Science Advances . The lenses have not yet been tested on humans and it is expected that it may take another five years to perfect them in people.
“We developed a method to fabricate a soft, smart contact lens that can monitor glucose levels in tears to indicate the diabetic condition in real time through a display with wireless operations,” the team stated. “The in vivo tests using a live rabbit … provided the substantial promise of future smart contact lenses for noninvasive health care monitoring using human eyes and tears.”