Glucose is a good target for optical sensing using surface-enhanced Raman spectroscopy, according to the study published in Advanced Materials.
Researchers used multiple layers of gold nanowire stacked on top of a gold film to make the tiny device. Standard nanofabrication techniques rely on a hard surface, like glass or a silicon wafer, but researchers needed a flexible nanostructure that would be more suitable for a wearable. The layered nanowire structure was made on a hard substrate and then lifted off and printed on a contact.
Surface-enhanced Raman spectroscopy uses the interactions between light and material to determine properties of the material’s molecular makeup. The contact lens enhances this form of spectroscopy with its narrow gaps within its nanostructure, which intensifies the Raman signal.
“Everyone knows tears have a lot to mine,” lead researcher Wei-Chuan Shih of the University of Houston said. “The question is, whether you have a detector that is capable of mining it, and how significant is it for real diagnostics.”
Researchers are still unsure how tear glucose levels are correlated with blood glucose levels, according to Shih.
This summer, Canadian start-up Medella Health raised $1.4 million to fund its in-development smart contact lens designed to monitor glucose levels and transmit data to a mobile device. They’re not the first to do so – Google (NSDQ:GOOG) caused a stir when it revealed in 2014 that its clandestine “X” research lab was working on a continuous glucose monitor that could be worn as a contact lens.