Double resonance interrogation of grating-coupled waveguides

Abstract

A method for using a double resonance effect within a grating-coupled waveguide (GCW) sensor, as generated from a light beam with a given span of wavelengths or angles, is provided. The method can be used for label-independent detection of biological and chemical agents, to interrogate biological-binding events or chemical reactions within a sensing region at increased sensitivity, and with decreased sensitivity to environmental perturbations. Also described is an optical interrogation system incorporating the method.

Description

FIELD OF INVENTION The present invention pertains in general to a sensor used for label-independent detection of biological and chemical agents. More particularly, the invention relates to 1) a method for using a double resonance effect within a grating-coupled waveguide (GCW) sensor, as generated from a light beam with a given span of wavelengths or angles, to interrogate biological-binding events or chemical reactions within a sensing region at increased sensitivity, and with decreased sensitivity to environmental perturbations, and 2) an optical interrogation system incorporating the method. BACKGROUND Evanescent field-based sensors are fast becoming a technology of choice for accurate label-free detection of a biological, biochemical, or chemical substance (e.g., cells, spores, biological or drug molecules, or chemical compounds). This technology typically involves using a grating-coupled waveguide (GCW) to sense a concentration change, surface adsorption, reaction, or the mer...

AI Technical Summary

Benefits of technology

The present invention relates in part to a method for increasing the biochemical sensitivity of an evanescent- or optical-field sensor having a grating-coupled waveguide (GCW) structure, as well as decreasing its sensitivity to environmental perturbations. The method, in part, involves generating a double resonance effect by using more than one propagation direction in the waveguide of the sensor from which is derived an output signal from the sensor. One can produce a sensitivity or improved signal-to-noise ratio (SNR) of greater than that obtained from using only a single propagation direction for biological or chemical sensors of grating-coupled waveguide (GCW) systems. Moreover, appropriate use of the resonances from the separate propagation directions can also aid in mitigating angular misalignments of the GCW sensor.

Alternatively, a method for using an evanescent-field or optical-field sensor like that described for detecting biological or chemical agents comprises: providing a sensor system having a optical-field sensing region comprising a substrate surface having at least a bio- or chemo-responsive layer; generating a double resonance within a grating-coupled waveguide of said system for either a given angle or wavelength; exposing an individual sensing region to an environment with analytes; and monitoring a response from the sensor system. The substrate can be modified with one or more coatings or layers of materials with desired surface chemistry, which enhance stable immobilization of said bio- or chemo-responsive layer.

Problems solved by technology

While there are many approaches for accomplishing these tasks, each has unique challenges associated with implementation, since the light beam output from the GCW sensor may be relatively weak and the presence of multiple sources of noise can degrade the light beam, especially in high-throughput screening applications.

Since the resonance condition of the GCW sensor is critically dependent on the angle of the light striking the microplate, repositioning of the plate in the detection device will manifest itself (at least in part) in the form of angular noise in the sensor instrument.

In other words, the sensor's extra-sensitivity can exacerbate environmental background noise.

The simultaneous desire for an extremely responsive sensor with high biochemical sensitivity and need for low susceptibility to environmental responses place unique constraints on the system designer.

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