A team of researchers have developed glucose-sensing contact lenses to detect glucose levels in tears as an alternative to invasive blood sugar testing procedures.

Wei-Chuan Shih, a researcher with the University of Houston and an associate professor of electrical and computer engineering, said that there is no non-invasive technique developed by far to test the glucose levels in body. Since blood is the key component used in testing sugar levels, using non-invasive methods is far from possible.

The researchers noted that glucose is present not only in blood but also in tears, therefore using tears to detect sugar with the help of contact lenses holds promise for the development of a non-invasive method. Shih said that it is well known fact that tears have plenty of components and in order for tears to be used in diagnostics, an appropriate detector is all that is needed to mine them.

Shih, whose NanoBioPhotonics Group laboratory works on nanoplasmonics-enabled optical biosensing, noted that glucose is a reliable target for optical sensing, which is applicable in surface-enhanced Raman scattering spectroscopy as well. The technique is named after Indian physicist C.V. Raman who discovered the scattering effect in 1928. The technique uses the information about how light scatters upon interaction with a particular material to determine the properties of molecules contained in it.

The researchers made a tiny device using layers of nanowires of gold stacked on top of a thin gold film. The device, which was produced using solvent-assisted nanotransfer printing, optimizes the surface-enhanced Raman scattering effect to be able to detect small molecular samples.

"3D stacking of plasmonic nanostructures is achieved using a solvent-assisted nanotransfer printing (S-nTP) technique to provide extremely dense and regular hot spot arrays for highly sensitive surface-enhanced Raman spectroscopy (SERS) analysis. Moreover, hybrid plasmonic nanostructures obtained by printing the nanowires on a continuous metal film or graphene surface show significantly intensified SERS signals due to vertical plasmonic coupling," explained the researchers in the study published in the journal Advanced Materials.

The idea of using contact lenses to find glucose is not new to the world of technology. Google has already submitted papers requesting patent rights for one such concept, the multi-sensor contact lens. Google claims that the contact lens is capable of detecting glucose in tears in addition to a number of other functionalities.

However, the researchers are said to have developed the glucose-sensing contact lenses just to show the versatility of the technology, which could be used for various other applications.

Photo: Niek Beck | Flickr