PDMS-based Bragg diffraction grating glucose sensor integrable in a contact lens

This paper proposes a glucose optical biosensor based on a Bragg diffraction grating fabricated in Poly(dimethylsiloxane) (or PDMS), suitable for integration in an ophthalmologic contact lens. One of the periodic layers of the grating is functionalized with Glucose Oxidase (GOx) to change its refractive index proportionally with glucose concentration and, therefore, modify the response of the resulting filter. Different layers are fabricated and characterized by spectroscopic ellipsometry considering different glucose concentrations. The proposed structure can detect changes in glucose levels from 80 mg/dl to 180 mg/dl, reducing its optical response to 65% at 521 nm, being capable of real-time, continuous and non-invasive sensing.