Planar Waveguide Surface Patterning for High Sensitivity Detection
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Solution Overview
Problem
Existing methods for preparing the outer surface of a planar waveguide to bind target samples along predetermined lines are inadequate, particularly for metals like native titanium, which are not suitable for forming a planar waveguide, limiting detection sensitivity in binding event detection.
Innovation Solution
A method involving a planar waveguide with an outer surface adapted for linker molecules, where photo-labile protecting groups on the linker molecules are exposed to light to create specific binding sites along predetermined lines, allowing target samples to be bound and scattered light to constructively interfere for enhanced detection sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If metal surfaces like native titanium are used for patterning nanostructures, then nanopatterning can be achieved, but the material is not suitable for forming a planar waveguide
Solution Approach 1:
The solution separates the patterning function from the waveguide material function by introducing a multi-layer structure: a planar waveguide layer made of suitable optical materials (silica, glass, polymers) and a separate metal layer (gold, silver, aluminum) deposited on top for nanopatterning. This segmentation allows each layer to fulfill its specific function without compromise.
Solution Approach 2:
The invention creates a composite structure combining optically transparent materials (for waveguide functionality) with metal materials (for nanopatterning capability). The planar waveguide consists of a core layer with high refractive index surrounded by cladding layers, with a metal layer deposited on the outer surface to enable interferometric nanopatterning while maintaining waveguide properties.
2Measurement precision
If target samples are bound along predetermined lines on the waveguide surface, then detection sensitivity is improved through constructive interference, but the preparation process becomes more complex
Solution Approach 1:
The method employs preliminary patterning actions using interferometric lithography to create precise line patterns on the waveguide surface before binding target samples. Photo-labile protecting groups are selectively removed along predetermined lines through controlled light exposure, creating ready-to-bind sites in advance. This preliminary structuring enables subsequent high-sensitivity detection without requiring complex real-time alignment during sample binding.
Solution Approach 2:
The invention applies local quality by creating distinct regions with different properties: areas with photo-labile protecting groups removed (exposed functional groups for binding) versus areas where protecting groups remain intact. This local differentiation along predetermined lines allows selective binding of target samples only in specific regions, enabling spatially resolved detection with enhanced sensitivity through constructive interference of evanescent fields.
3Manufacturing precision
If photo-labile protecting groups are removed to create binding sites, then specific binding locations are achieved, but additional processing steps are required
Solution Approach 1:
The invention replaces mechanical or chemical etching methods with photo-lithographic patterning to create precise binding sites. By using light exposure to remove photo-labile protecting groups, the method achieves high spatial precision in defining binding locations. The interferometric illumination pattern creates precise line patterns through optical interference, eliminating the need for step-by-step mechanical patterning processes.
Solution Approach 2:
The method utilizes parameter changes in the photo-labile protecting groups' response to light exposure. By controlling the wavelength, intensity, and duration of light exposure, precise spatial patterns of bound and unbound protecting groups are created. The photo-labile groups undergo chemical transformation when exposed to specific wavelengths of light, enabling controlled removal only in predetermined line patterns while maintaining integrity elsewhere.
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 method enables high detection sensitivity by creating specific binding sites along predetermined lines, allowing scattered light to interfere constructively, thereby increasing the detectability of target samples, and can be applied to materials like Ta2O5, TiO2, or Si3N4 waveguides.
Implementation Method 1
an evanescent field of coherent light coupled into and propagating through the planar waveguide is scattered at target samples arranged along the plurality of predetermined lines
Implementation Method 2
the scattered light constructively interferes in a predetermined detection location with a difference in optical path length which is an integer multiple of the wavelength of the coherent light
Implementation Method 3
the light diffracts at the plurality of predetermined lines so as to interfere in predetermined directions in the planar waveguide
Implementation Method 4
those photo-labile protecting groups arranged along the plurality of predetermined lines are exposed to light of a predetermined wavelength so as to remove the exposed photo-labile protecting groups from the functional groups
Data Source
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AI summary
According to the invention there is provided a method for preparing the outer surface (11) of the planar waveguide (1) for binding target samples along the plurality of predetermined lines (4). The method comprises the following steps. Providing a planar waveguide (1) with an outer surface (11) adapted for attachment of a head group (21) of a linker molecule (2) to the outer surface (11). Sequentially applying at least one plurality of linker molecules (2, 5) to the outer surface (11). Each plurality of the at least one plurality of linker molecules (2, 5) assembles to form an individual layer of linker molecules (2, 5) with individual layers formed one above the other starting from the outer surface (11) of the planar waveguide (1). Each linker molecule (2, 5) comprises a functional group (22, 52) and the head group (21, 51) which is capable of attaching to the outer surface (11) of the planar waveguide (1) or to the functional groups (22) of the preceding layer of linker molecules (2). The functional groups (52) of the plurality of linker molecules (5; 2) of the uppermost layer are bound to photo-labile protecting groups (3) so that each functional group (52) bound to a said photo-labile protecting group (3) is incapable of attaching a complementary functional group of a further molecule. Exposing those photo-labile protecting groups (3) of the uppermost layer arranged along a plurality of predetermined lines (4) to light of a predetermined wavelength to remove the exposed photo-labile protecting groups (3) from the functional groups (52) to make these functional groups (52) capable of attaching a complementary functional group of a further molecule. (Fig. 1)