Optical transduction technique utilizing gratings with a potential application towards biosensing

There is a need for technology capable of providing unique, sensitive, and rapid detection against threats posed by biological weapons, infectious diseases, and environmental pathogens. A potential solution presented herein is a photonic-based biosensor that utilizes a pair of diffractive phase gratings. This concept is merged with the ability to use surface chemistry techniques to precisely immobilize receptors at specific locations to create optical grating structures out of biological materials. The sensor is configured such that a change in the optical phase of diffracted laser light results when the refractive index profile of the 'bio-grating' is altered upon analyte binding to the molecular receptors within the grating structure. Because of the phase nature of the detection technique and the noise reduction nature of the grating geometry, the method is inherently sensitive with a potential for detecting small amounts of the unlabeled analyte. The optical transduction technique utilizing the gratings is described in detail. Data is presented addressing the analyte detection sensitivity from results generated from ideal optical glass gratings of varying etch depth. The fabrication techniques for creating gratings out of biological materials are discussed.