A new contact lens technology from the University of Houston samples glucose levels in tears.

The tiny device, built from multiple layers of gold nanowires stacked on top of a gold film, employs a technique called surface-enhanced Raman scattering to detect small molecular samples.

Surface-enhanced Raman scattering uses information about how light interacts with a material to determine molecular properties.

The device, produced using solvent-assisted nanotransfer printing, enhances the sensing properties of the technique by creating “hot spots,” or narrow gaps within the nanostructure.

Although traditional nanofabrication techniques rely on a hard substrate – usually glass or a silicon wafer – the researchers wanted a flexible nanostructure more suited to wearable electronics. The layered nanoarray was produced on a hard substrate but lifted off and printed onto a soft contact.

The sensor's accurate monitoring of the glucose level in human tears provides an alternative approach for non-invasive glucose monitoring.