Optical Detection System for Microfluidic Alignment
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Solution Overview
Problem
Current optical detection systems for microfluidic devices are large, expensive, and inflexible, with alignment and focusing processes that require flowing fluorescent dye, which is costly and time-consuming, and often unstable.
Innovation Solution
An optical detection system with microfluidic devices featuring etched optical alignment marks on a substrate, bonded with a second substrate to cover channels, using a light-emitting diode and objective lens for alignment and focusing, allowing for alignment and focusing without flowing dye, utilizing a LED light source and a custom-designed high-numerical-aperture objective lens for efficient signal detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple high quality lasers and CCD cameras are employed for fluorescence excitation and detection, then detection sensitivity is improved, but system cost and size increase
Solution Approach 1:
The patent combines multiple functions into a single integrated optical detection system. Instead of using separate lasers and CCD cameras for different channels, the invention uses a single optical detection system with a movable stage that can be positioned over different channels, eliminating the need for multiple independent detection systems while maintaining the ability to detect fluorescent signals from multiple channels.
Solution Approach 2:
The optical detection system is designed to be universal and can detect fluorescent signals from any channel by simply moving the stage to the appropriate position. This multi-functional design allows a single system to replace multiple specialized systems, reducing overall system complexity and cost while maintaining detection sensitivity across all channels.
2Measurement precision
If fluorescent dye is flowed through channels for alignment and focusing, then optical alignment accuracy is improved, but time consumption and cost increase
Solution Approach 1:
The patent incorporates optical alignment marks that are pre-formed in the microfluidic device structure during manufacturing. These alignment marks are created using photolithography and etching processes, so they are already in place before the device is delivered. This preliminary action eliminates the need for time-consuming alignment procedures using fluorescent dye, as the alignment features are permanently integrated into the device.
Solution Approach 2:
Instead of using fluorescent dye as a temporary alignment reference, the invention uses permanent optical alignment marks that are etched into the substrate. These marks serve as a stable, long-lasting copy of the channel positions, providing consistent alignment references without the need for flowing and flushing dye through the channels.
3Ease of operation
If fluorescent dye is flushed out of channels after focusing, then alignment is completed, but additional time and complexity are required
Solution Approach 1:
The patent extracts the alignment function from the fluorescent dye-based process and integrates it directly into the device structure through permanent optical alignment marks. This extraction eliminates the need for the flushing operation entirely, as the alignment marks remain in place without requiring dye to be flowed or flushed. The alignment process is simplified to simply reading the position of these permanent marks.
4Measurement precision
If fluorescent dye is used for alignment, then optical alignment is achieved, but cost and stability issues arise
Solution Approach 1:
The patent replaces expensive and unstable fluorescent dye with permanent optical alignment marks that are etched into the substrate. These marks are made from the same materials as the device structure (such as silicon or glass), making them stable, reliable, and cost-effective. The alignment marks do not degrade or change properties over time, unlike fluorescent dye which can be unstable and expensive.
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
The system is more compact, cost-effective, and flexible, enabling rapid alignment and focusing without the need for expensive and unstable dye, allowing for efficient detection of fluorescent signals from multiple channels with improved sensitivity and reduced operational complexity.
Implementation Method 1
a light-emitting diode, means for collimating light emitted by the light-emitting diode, an objective lens, means for directing the collimated light through the objective lens onto the microfluidic device
Implementation Method 2
an objective lens, means for directing the collimated light through the objective lens onto the microfluidic device and means for detecting a signal emitted from the microfluidic device
Implementation Method 3
aligning and focusing an optical detection system... using light reflected from the one or more optical alignment marks
Implementation Method 4
detecting fluorescent signals... means for detecting a signal emitted from the microfluidic device
Data Source
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AI summary
An optical detection system (100) for a microfluidic device (165) is described. The system (100) includes a microfluidic device (165) including alignment marks; an LED (110); means for collimating light emitted by the LED (110); an objective lens (160); means for directing the collimated light through the objective onto the microfluidic device (165); and means (150) for detecting a signal emitted from the microfluidic device (165). The working distance between the objective (160) and the device (165) allows light from an external LED (110) or laser to be brought in along a diagonal path to illuminate the microfluidic device (165). The microfluidic device (165) includes multiple channels and multiple closed optical alignment marks having curved walls. The marks are illuminated for alignment and focusing purposes by light brought in on a diagonal path from an external LED (110).