Silicon Microparticles Uniform Oxide Layer Fabrication
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Solution Overview
Problem
Existing methods for coating silicon microparticles with a transparent layer to achieve constructive light interference for enhanced fluorescence signals are not applicable to small microparticles, as they result in irregular or different thicknesses, leading to inconsistent fluorescence readouts in assays.
Innovation Solution
A novel wafer-based microfabrication process involving a sandwich structure wafer with a bottom layer, insulator layer, and top layer, where the top layer is etched to delineate microparticles, the insulator layer is removed, and a thin film layer is deposited on the microparticles before lifting them off, ensuring a consistent and controlled oxide layer thickness for optimal fluorescence interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional coating methods are used on small microparticles, then the coating process becomes simple, but the oxide layer thickness becomes irregular and inconsistent
Solution Approach 1:
The patent applies preliminary action by performing the oxide layer deposition while the microparticles are still attached to the wafer substrate, before the microparticles are released. This allows the deposition process to benefit from the wafer's large surface area and controlled environment, ensuring uniform thickness. After deposition, the microparticles are released from the wafer, combining the simplicity of handling small particles with the precision of controlled deposition.
2Illumination intensity
If an oxide layer is added to achieve constructive light interference, then fluorescence signal is enhanced, but the layer thickness must be precisely controlled
Solution Approach 1:
The patent replaces mechanical/conventional coating methods with a wafer-based microfabrication process that utilizes established semiconductor manufacturing techniques. This substitution allows for precise control of oxide layer thickness through controlled deposition processes on the wafer, ensuring optimal thickness for constructive light interference and fluorescence enhancement.
3Manufacturing precision
If wafer-based microfabrication is used for small microparticles, then oxide layer thickness becomes uniform, but the process complexity increases
Solution Approach 1:
The patent applies universality by adapting existing wafer-based microfabrication processes, originally designed for larger substrates, to work with small microparticles. The same deposition and processing techniques used for wafer-scale manufacturing are applied here, allowing the benefits of precise control to extend to small particles without requiring entirely new process development.
Solution Approach 2:
The patent uses preliminary action by maintaining microparticle attachment to the wafer during the oxide layer deposition process. This allows the complex wafer-based processes to be applied to small particles while preserving the precision benefits, and the microparticles are only released after the oxide layer is uniformly deposited.
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 produces microparticles with a uniform oxide layer, enabling observable fluorescence signals during assays, improving the reliability and consistency of fluorescence readouts in biological assays.
Implementation Method 1
destructive light interference occurring right at the surface of the partially reflective silicon microparticles
Implementation Method 2
fluorescent probes (typically ssDNA probes labelled with FAM fluorophore at the 5' end)
Implementation Method 3
The reflection coefficient of a polished silicon wafer (or SOI (silicon-on-insulator) wafer) is about 35-40 % in the 500-700 nm wavelength range
Data Source
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AI summary
The present invention discloses silicon microcarriers suitable for fluorescent assays as a well as a method of producing such microcarriers. The method comprises the steps of providing a SOI wafer comprising a bottom layer of monocristalline silicone, an insulator layer and a bottom layer of monocristalline silicon, delineating microparticles, etching away the insulator layer and then depositing an oxide layer on the wafer still holding the microparticles before finally lifting-off the microparticles.