Blood testing has been the standard option for checking glucose levels, but a new technology could allow non-invasive testing via a contact lens that samples glucose levels in tears. Glucose is present not only in the blood but also in tears, and accurate monitoring of the glucose level in human tears by employing a contact-lens-type sensor can be an alternative approach for noninvasive glucose monitoring
Researcher at the University of Houston have reported in the journal of `Advanced Materials’ development of optical sensing lens using surface-enhanced Raman scattering spectroscopy to measure glucose molecules in tears. The tiny device, built from multiple layers of gold nanowires stacked on top of a gold film and produced using solvent-assisted nanotransfer printing, optimises the use of surface-enhanced Raman scattering to detect small molecular samples.
Surface-enhanced Raman scattering - named after Indian physicist C.V. Raman, who discovered the effect in 1928 - uses information about how light interacts with a material to determine properties of the molecules that make up the material.
The device enhances the sensing properties of the technique by creating "hot spots," or narrow gaps within the nanostructure which intensified the Raman signal, the researchers said.
Scientists know that glucose is present in tears, but researchers have said that exact correlation of tear glucose levels with blood glucose levels hasn't been established.
Although traditional nanofabrication techniques rely on a hard substrate - usually glass or a silicon wafer - Shih said researchers wanted a flexible nanostructure, which would be more suited to wearable electronics. The layered nanoarray was produced on a hard substrate but lifted off and printed onto a soft contact, he said.
Source: University of Houston