Curved Waveguide Lines for Label-Free Binding Detection
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Solution Overview
Problem
Current biosensor techniques for detecting binding affinities rely on fluorescent labels, which are costly, prone to steric hindrance, photobleaching, and quenching effects, and require additional preparation steps, leading to potentially falsified results.
Innovation Solution
A device featuring a planar waveguide with curved incoupling and outcoupling lines that diffract coherent light to produce a signal representative of binding affinities without the need for labels, utilizing an evanescent field and diffraction to detect changes in intensity at a second focal location, allowing for label-free detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluorescent labels are used to detect binding affinities, then the binding events can be detected, but the results are falsified due to steric hindrance, photobleaching, and quenching effects
Solution Approach 1:
The invention extracts and removes the fluorescent label from the detection system, using label-free detection based on refractive index changes. This eliminates the harmful effects of steric hindrance, photobleaching, and quenching while maintaining the ability to detect binding events through changes in the optical properties of the waveguide caused by the bound analyte molecules themselves
Solution Approach 2:
The invention replaces the chemical/optical mechanism of fluorescent labeling with a physical mechanism based on refractive index detection. Instead of using fluorescent molecules that emit light upon excitation, the system detects changes in the refractive index at the waveguide surface caused by mass accumulation during binding events, fundamentally changing the detection mechanism to eliminate label-related artifacts
2Reliability
If fluorescent labels are used for detection, then binding events can be visualized, but additional preparation steps are required and costs increase
Solution Approach 1:
The invention removes the fluorescent label component entirely from the system, eliminating the need for labeling preparation steps. The detection is performed directly on the native analyte molecules through their interaction with the waveguide's evanescent field, reducing both procedural complexity and material costs while maintaining detection capability
Solution Approach 2:
The analyte molecules themselves serve as the detection signal source through their intrinsic optical properties (refractive index), rather than requiring external fluorescent tags. The binding events directly modulate the optical properties of the waveguide, allowing the system to detect what is naturally present without requiring additional labeling reagents or preparation procedures
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach eliminates the need for labeling, reduces costs, and minimizes interference, providing a more accurate and cost-effective method for detecting binding affinities by using the diffraction of coherent light to constructively interfere at a focal location, thus enhancing the reliability of the binding affinity signal.
Implementation Method 1
The coherent light propagates through the planar waveguide under total reflection with an evanescent field of the coherent light propagating along the outer surface of the planar waveguide
Implementation Method 2
The depth of penetration of the evanescent field into the medium of lower refractive index at the outer surface of the planar waveguide is in the order of magnitude of a fraction of the wavelength of the coherent light propagating through the planar waveguide
Implementation Method 3
A plurality of binding sites capable of binding a target sample is attached to the outer surface. The attached binding sites are arranged along diffraction lines of a plurality of diffraction lines arranged in an outcoupling section of the planar waveguide, so that in operation a portion of the evanescent field is diffracted at the binding sites bound to the target sample
Data Source
Figure 1~2
Figure 3~5
Figure 6
AI summary
A device (1) for use in the detection of binding affinities comprises a planar waveguide (2) arranged on a substrate (22). The waveguide (2) has an outer surface (21) and a plurality of incoupling lines (31) for coupling a beam of coherent light into the waveguide (2) such that a parallel beam of coherent light (62) propagates along the waveguide (2). The incoupling lines (31) are curved and have an increasing distance between adjacent incoupling lines (31). A divergent beam of coherent light (61) of a predetermined wavelength is coupled into the waveguide (2) such that it propagates along the waveguide (2). A plurality of binding sites (51) is attached to the outer surface (21) along at least one further plurality of diffraction lines arranged in an outcoupling section of the waveguide (2). These diffraction lines comprise a plurality of curved outcoupling lines (41) having a decreasing distance between adjacent outcoupling lines. They decouple a diffracted portion of coherent light from the planar waveguide (2), and the decoupled portion of coherent light (63) converges into a predetermined second focal location (631).