Diabetic contacts: An eye on Raman glucose sensors

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  • Published: Oct 1, 2016
  • Author: David Bradley
  • Channels: Raman
thumbnail image: Diabetic contacts: An eye on Raman glucose sensors

Glucose monitoring

This illustration shows the schematic procedure for the fabrication of a surface-enhanced Raman scattering contact lens via transfer printing. Credit Shih et al/University of Houston

People with diabetes, and others, must monitor their blood glucose concentration so that they can take appropriate medication in a timely manner. This usually involves the use of a pin-prick test, which many people find painful and inconvenient. Now, contact lenses that use Raman spectroscopy to measure glucose in tears could offer a wearable and non-invasive testing alternative.

At present, there is no non-invasive blood sugar monitoring technology available to clinicians or patients, according to Wei-Chuan Shih of the University of Houston. However, working with colleagues there and in Korea Shih has developed an alternative and offers details in the journal Advanced Materials. It has been known for some time that glucose is a good target for optical sensing, and its detection is entirely amenable to surface-enhanced Raman scattering (SERS) spectroscopy, explains Shih, who is an associate professor of electrical and computer engineering. His team, the NanoBioPhotonics Group, works on optical biosensing enabled by nanoplasmonics.

SERS sensing

Shih initially developed the basic SERS technology for glucose sensing while a graduate student at Massachusetts Institute of Technology (MIT) and holds two patents for technologies related to directly probing skin tissue using laser light to extract information about glucose concentrations. The new work involves development of a tiny device, built from multiple layers of gold nanowires stacked on top of a gold film and made by solvent-assisted nanotransfer printing. The layered nanoarray was produced on a hard substrate but lifted off and printed onto a soft contact, Shih explains. The device is optimized for SERS and can work with the tiny samples available in the form of tears on the surface of the eye. The device's hot spots are narrow gaps within the nanostructure which provides the requisite Raman signal boost.

Of course, sensor contact lenses themselves have been in the patent offices for some time, with search engine giant Google having patented a multi-sensor contact lens some time ago. Shih's technology could have several uses beyond teardrop glucose sensing.

Tearful technique

It is known that glucose is present in tears, but whether or not tear glucose concentrations correlate with blood glucose levels has not yet been established and that biomedical research needs to take place before diabetic contact lenses become a marketable device. Nevertheless, Shih stresses that the more important finding emerging from this work is that the structure is an effective mechanism for using SERS in such a unique way that could be extended to detecting other biomarkers for wearable diagnostics.

Shih worked with Yeon Sik Jung, Jae Won Jeong and Kwang-Min Baek, all with the Korea Advanced Institute of Science and Technology; Seung Yong Lee of the Korea Institute of Science and Technology, and Houston's Md Masud Parvez Arnob on the current development.

Related Links

Adv Mater 2016, online: "3D Cross-Point Plasmonic Nanoarchitectures Containing Dense and Regular Hot Spots for Surface-Enhanced Raman Spectroscopy Analysis"

Article by David Bradley

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

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