Imager Chemisorption Layer Pixel Isolation
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Solution Overview
Problem
Image sensors used in microfluidic devices face challenges in achieving improved spatial resolution due to cross-talk between pixels caused by random bonding of molecules, which is exacerbated by unreliable mechanical polishing processes.
Innovation Solution
The active surface of the image sensor is selectively covered with chemical anchoring agent molecules localized over each pixel, reducing cross-talk by ensuring that fluorescent molecules emit light spatially separated between pixels, using photolithographic patterning and a chemisorption layer to ensure precise deposition and bonding of anchoring agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mechanical polishing is used to remove chemical anchoring agents outside wells, then manufacturing process is simplified, but manufacturing precision and reliability deteriorate due to substantial variations
Solution Approach 1:
The patent replaces the mechanical polishing process with a chemical etching process using buffered oxide etch (BOE) to remove chemical anchoring agents from regions outside the wells. This substitution eliminates the substantial manufacturing variations associated with mechanical polishing while achieving the same functional outcome of clearing anchoring agents from non-well areas, thereby improving manufacturing precision without significantly complicating the manufacturing process.
2Ease of manufacture
If chemical anchoring agent layer is deposited over entire active surface, then ease of manufacture is improved, but measurement precision deteriorates due to cross-talk between pixels
Solution Approach 1:
The patent segments the chemical anchoring agent distribution by using buffered oxide etch (BOE) to selectively remove anchoring agents from regions outside the wells, while preserving them within the well regions. This segmentation creates spatially distinct zones of anchoring agent presence, ensuring that fluorescent molecules bound to analytes in one well do not cause cross-talk with adjacent pixels, thereby improving spatial resolution while maintaining ease of manufacture through a relatively simple etching step.
Solution Approach 2:
The patent implements local quality by creating non-uniform distribution of chemical anchoring agents across the active surface. Through selective etching, anchoring agents are retained only in specific localized regions (within wells) while being removed from other regions. This localized presence of anchoring agents ensures that fluorescence emission is spatially confined to well-defined areas, improving measurement precision without requiring complex deposition processes.
3Measurement precision
If wells are etched into active surface, then spatial resolution is improved by reducing cross-talk, but device complexity increases due to additional manufacturing steps
Solution Approach 1:
The patent applies preliminary action by forming the well structures into the active surface before depositing the chemical anchoring agent layer. This sequence ensures that when anchoring agents are deposited, they naturally concentrate within the well regions. The subsequent BOE etching step then selectively removes anchoring agents from non-well areas, achieving spatial resolution improvement through a streamlined process that avoids the need for complex post-deposition patterning or multiple etching steps.
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 enhances the spatial resolution of image sensors by minimizing cross-talk and improving the accuracy of molecule imaging, allowing for better detection and sequencing of analytes like DNA.
Implementation Method 1
The active surface of the image sensor is selectively covered with chemical anchoring agent molecules localized over each pixel... using photolithographic patterning and a chemisorption layer to ensure precise deposition and bonding of anchoring agents
Implementation Method 2
A fluorescent emitter is selectively attached to the molecules and light emitted by the fluorescent molecules is captured and converted into image data by the image sensors
Implementation Method 3
using photolithographic patterning and a chemisorption layer to ensure precise deposition and bonding of anchoring agents
Data Source
AI summary
An imager may include an array of pixels formed on a substrate. A chemisorption layer such as a planar chemisorption layer may be deposited over the array of pixels. The chemisorption layer may include active sites that bond with anchoring molecules. The anchoring molecules may be bonded to the planar chemisorption layer in only localized regions each covering a respective pixel of the array of pixels. The image sensor may include a photoresist layer that covers the chemisorption layer. Openings in the photoresist layer may define the boundaries of the localized regions. The anchoring molecules may be bonded only with the chemisorption layer without bonding to the photoresist layer. The anchoring molecules may serve to bond with analyte molecules. By forming the anchoring molecules within only localized regions centered over respective pixels, spatial resolution of the imager when imaging the analyte molecules may be improved.