Tear Fluid Photonic Crystal Contact Lens Noninvasive Glucose Sensors

Authored by: Asher Sanford A. , Baca Justin T.

Handbook of Optical Sensing of Glucose in Biological Fluids and Tissues

Print publication date:  December  2008
Online publication date:  December  2008

Print ISBN: 9781584889748
eBook ISBN: 9781584889755
Adobe ISBN:


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We are developing a photonic crystal contact lens sensor for the noninvasive determination of glucose in tear fluid. Success requires a photonic crystal sensor with the sensitivity to glucose required to differentiate normal levels from hyperglycemic and hypoglycemic levels. In addition, the tear glucose levels need to track those of blood. In this chapter we review our progress in developing a photonic crystal glucose sensor for incorporation into a contact lens. We also review all previous tear fluid glucose studies, which, while suggesting that tear glucose concentrations tracks that of blood, significantly disagree as to the tear glucose concentrations in both normal and diabetic subjects. These studies also disagree as to the relationship between blood and tear fluid glucose concentrations. We also present new measurements of tear glucose concentrations by using a method designed to avoid tear stimulation. We conclude that the various previous tear collection methods biased the measured tear glucose concentrations. We also review recent studies which attempt to monitor tear glucose concentrations in situ by using contact lens-based sensing devices. On the basis of these results, we are optimistic about the future of in vivo tear glucose sensing.

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