Researchers have developed a new technology that could allow non-invasive testing of glucose levels, via a contact lens that samples glucose levels in tears.
Blood testing is the standard option for checking glucose levels, researchers said. "There's no non-invasive method to do this. It always requires a blood draw. This is unfortunately the state of the art," said WeiChuan Shih, from the University of Houston in the US.
Current method to monitor glucose levels involves a medication process along with a painful finger-prick blood test.
Glucose is a good target for optical sensing, and can be used as an alternative approach, the study said.
“It should be noted that glucose is present not only in the blood but also in tears, and thus accurate monitoring of the glucose level in human tears by employing a contact-lens-type sensor can be an alternative approach for non-invasive glucose monitoring,” said Wei-Chuan Shih, Associate Professor at University of Houston in Texas, US.
The researchers developed a tiny device built with multiple layers of gold nano wires and gold film that was produced, using solvent assisted nano transfer printing.
This component strengthens a technique called surface-enhanced Raman scattering — named after Indian physicist C.V. Raman, who discovered the effect first in 1928 — which gauges how light interacts with a material to determine its molecular composition, the researchers stated.
Further, the device enhances the sensing properties of the technique by creating “hot spots” or narrow gaps within the nano structure which intensified the Raman signal.
Traditional nano fabrication techniques rely on a hard substrate — usually glass or a silicon wafer — but researchers wanted a flexible nano structure which would be more suited to wearable electronics, Shih said.
The layered nanoarray was produced on a hard substrate but lifted off and printed onto a soft contact, Shih said in the paper published in the journal Advanced Materials.
Although non-invasive glucose sensing is just one potential application of the technology, it provided a good way to prove the technology, he said.
Moreover, the device is also an effective mechanism for using surface-enhanced Raman scattering spectroscopy.
