The ability to collect tears in an effective way and to measure their pH and levels of biomarkers in real time is highly desirable. One approach that is actively being explored is the idea of contact lens biosensors. Such contact lenses could be designed to include tiny channels on their surfaces for guiding the flow of tears into tiny reservoirs for collection and monitoring.
Pliable and transparent materials, known as hydrogels, are currently being used commercially to make contact lenses; they are easy to work with and cost effective. A collaborative team has developed a fabrication method to meet all the challenges in making a hydrogel contact lens for biomarker sensing. The team began by optimizing the components of the hydrogel to obtain elastic characteristics that would allow it to be engineered into various shapes with a smooth surface profile. They next fashioned microchannels in the hydrogel with the use of a 3D printed mold. The final step in the fabrication process was to enclose the hydrogel channels by bonding an additional layer of hydrogel onto the microchannel surface. The team next prototyped sensors to collect, test for, and measure pH levels of artificial tears flowing through the microchannels. The results showed an acceptable and predicted range of sodium detection for diagnostic purposes.
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