Transparent biosensors in contact lenses – made visible in this artist’s rendition – could soon help track our health. [Image from Jack Forkey/Oregon State University]
2. Monitoring glucose through contact lenses
Biosensing contact lenses may not be able to self-heal like “The Terminator,” but they could measure blood glucose and detect other signs of disease in the future.
Gregory S. Herman, an Oregon State University chemical engineering professor, first used biosensing when he and 2 colleagues invented a compound that had indium gallium zinc oxide (IGZO), creating a semiconductor. The IGZO combination produced higher resolution displays for televisions, smartphones and tablets.
To test the feasibility of biosensing lenses, Herman and his colleagues inexpensively developed IGZO electronics to create a biosensor that had a transparent sheet of IGZO field-effect transistors and glucose oxidase. Adding glucose to the mixture oxidized the blood sugar and changed the pH levels, which changed the electrical current that was flowing through the IGZO transistor.
Electrical changes in biosensors typically measure glucose concentrations within interstitial fluid under a diabetic’s skin. However, the concentration of glucose is much lower in the eye, so biosensors in contact lenses would have to be more sensitive before it could be used as a monitor.
Herman created nanostructures within the IGZO biosensor to be able to detect the presence of glucose in lower concentrations than what is found in tears.
Herman and his team aren’t the only ones working on glucose-sensing contact lenses: Novartis and Google were recently working on their own set of smart contact lenses. Novartis announced in November 2016 that it was backing off of a 2016 start date to take its contact lenses into a clinical trial.
Read about the glucose monitoring contact lenses.
