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]
Oregon State University researchers are set to present a study that suggests transparent biosensors that are embedded into contact lenses could provide insight for doctors and patients without the need for invasive blood tests.
“These biosensors probably won’t put blood labs out of business.But I think that we can do a lot of diagnostics using information that can be extracted from tear drops in the eye,” said Oregon State University chemical engineering professor Gregory S. Herman in an American Chemical Society press release.
Biosensing lenses could be used to track drug use or possibly detect early signs of cancer and other serious medical conditions.
Herman 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.
He then began applying this technology to biomedical applications because he wanted to help diabetics easily and continuously monitor their blood glucose levels and with more efficiency.
About 29.1 million people (9.1% of the population) in the U.S. have diabetes, according to the Centers for Disease Control and Prevention. Of that number, 21 million are diagnosed while 8.1 million go undiagnosed.
There are a lot of continuous blood glucose monitors on the market that are meant to replace the traditional pricking of the finger and testing method. Blood glucose monitors help reduce the risk of diabetes complications like neuropathy, kidney damage, eye damage, foot damage and more. However, some of these closed-loop monitors require a sensor or electrode to be placed under the skin, causing skin irritation or infection.
Herman suggests that biosensing contact lenses could eliminate the complications that arise from closed-loop blood glucose monitors and could even improve compliance because it can easily be replaced on a daily basis.
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.
More than 2,500 biosensors that measure different bodily functions can be embedded into a 1 mm square patch of an IGZO contact lens, according to Herman. The biosensors could track vital health information and transmit that data to smartphone once the biosensors are further developed.
Novartis and Google were recently working on their own set of contact lenses that could measure blood glucose levels in diabetic patients. Novartis announced in November 2016 that it was backing off of a 2016 start date to take its contact lenses into clinical trial.
Biosensing lenses are not the first application of the IGZO system. Herman’s team previously used the IGZO system in catheters to measure uric acid from the kidneys. They also hope to use it to detect cancer and other serious conditions.
The research is being presented today at the 253rd National meeting and Exposition of the American Chemical Society.
[Want to stay more on top of MDO content? Subscribe to our weekly e-newsletter.]
