Korean researchers have designed a “smart contact lens” that may one day allow patients with diabetes and glaucoma to self-monitor blood glucose levels and internal eye pressure.*
The study was conducted by researchers at Ulsan National Institute of Science and Technology (UNIST) and Kyungpook National University School of Medicine, both of South Korea.
Most previously reported contact lens sensors can only monitor a single analyte (such as glucose) at a time, and generally obstruct the field of vision of the subject.
The design is based on transparent, stretchable sensors that are deposited on commercially available soft-contact lenses.
Electrodes based on a hybrid graphene-silver nanowire material can measure glucose in tears. Internal eye pressure changes are measured by a sandwich structure whose electronic characteristics are modified by pressure.
Inductive coupling — batteries not required
Both of these readings are transmitted wirelessly using “inductive coupling” (similar to remote charging of batteries), so no connected power source, such as a battery, is required. This design also allows for 24-hour real-time monitoring by patients.
The researchers conducted in-vivo and in-vitro performance tests using a live rabbit and bovine eyeball.
The team expects that the research could also lead to developing biosensors capable of detecting and treating various other human diseases, or used as a component in other biomedical devices.
The study results were published in the March issue of the journal Nature Communications. The study was supported by the 2017 CooperVision Science and Technology (S&T) Awards Program.
* Diabetes is the most common cause of high blood sugar levels. Intraocular pressure is the largest risk factor for glaucoma, a leading cause of human blindness.
How the smart contact lens works
Abstract of Wearable smart sensor systems integrated on soft contact lenses for wireless ocular diagnostics
Wearable contact lenses which can monitor physiological parameters have attracted substantial interests due to the capability of direct detection of biomarkers contained in body fluids. However, previously reported contact lens sensors can only monitor a single analyte at a time. Furthermore, such ocular contact lenses generally obstruct the field of vision of the subject. Here, we developed a multifunctional contact lens sensor that alleviates some of these limitations since it was developed on an actual ocular contact lens. It was also designed to monitor glucose within tears, as well as intraocular pressure using the resistance and capacitance of the electronic device. Furthermore, in-vivo and in-vitro tests using a live rabbit and bovine eyeball demonstrated its reliable operation. Our developed contact lens sensor can measure the glucose level in tear fluid and intraocular pressure simultaneously but yet independently based on different electrical responses.
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