While we have already heard about contact lenses that monitor medical conditions, such lenses are often made from non-traditional materials. A new one, however, is composed of the same hydrogel as regular store-bought contacts, potentially making it much more user-friendly.
Diagnostic contact lenses work by analyzing the wearer's tears, measuring levels of biomarker molecules associated with conditions such as diabetes. These experimental lenses are typically made of transparent polymers, which aren't as soft and comfortable – or as inexpensive to manufacture – as the hydrogel commonly used for commercial lenses.
With this in mind, an international team of researchers started by tweaking the formulation of an existing hydrogel, making it more elastic. Doing so allowed it to better hold its shape when molded, while still maintaining a smooth surface texture.
The scientists then poured the hydrogel into a 3D-printed mold with tiny raised ridges on its surface. Those ridges formed microchannels on the surface of what would serve as the base of the lens. Next, another layer of hydrogel was bonded to that side of the base – this enclosed the channels, making them more like tunnels through the lens as opposed to open trenches on its surface.
In the finished product, each microchannel leads to a tiny well containing a reagent chemical. Depending on how much of a given biomarker is present in the tear fluid that makes its way to that well, the reagent will respond in an observable manner, such as by changing color.
"The production of the successful prototype described here and the continuing efforts to perfect its capabilities mark a significant advance in contact lens biosensing," says Dr. Ali Khademhosseini, CEO of the Los Angeles-based Terasaki Institute, which is one of the project partners.
A paper on the study was recently published in the journal Lab on a Chip.
Source: Terasaki Institute