In-situ Microfluidic Feature Calibration via Optical Reflection
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Solution Overview
Problem
Geometric variability in disposable microfluidic devices due to manufacturing tolerances can lead to inaccurate measurements, failing to meet regulatory standards, and existing solutions are often costly or difficult to implement.
Innovation Solution
An analytical system that includes a laser to direct light toward microfluidic features in a multiple layer test cartridge, a sensor to receive reflections from capping layers, and a controller to determine the depth of the microfluidic features for calibration, allowing for accurate measurement and testing without requiring tight manufacturing tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If tight manufacturing tolerances are applied to microfluidic device thickness, then measurement accuracy is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent performs thickness measurement and calibration before the device is used for its intended function. By measuring the actual thickness of each microfluidic device during manufacturing or initial setup, the system establishes a calibration factor that compensates for thickness variations. This preliminary action eliminates the need for tight manufacturing tolerances, as each device is individually characterized and adjusted.
Solution Approach 2:
The patent changes the operational parameters of the measurement system by introducing calibration factors that are specific to each device's actual thickness. Instead of maintaining a fixed threshold or standard thickness, the system adjusts measurement parameters (such as optical path length compensation factors) based on the measured thickness of each individual device, thereby achieving accurate measurements across a range of thickness values.
2Measurement precision
If tight manufacturing tolerances are applied to microfluidic device thickness, then measurement accuracy is improved, but manufacturing yield decreases
Solution Approach 1:
By performing thickness measurement and calibration as a preliminary step, the system accepts devices with a broader range of thickness values that would otherwise be rejected by tight tolerance specifications. Each device is measured, calibrated, and assigned a correction factor, allowing it to be used successfully despite thickness variations, thereby increasing manufacturing yield.
Solution Approach 2:
Each microfluidic device essentially calibrates itself through the measurement process. The system measures the actual thickness of each device and uses that measurement to determine the appropriate calibration factor for that specific device. This self-service approach allows devices to compensate for their own manufacturing variations without requiring external intervention or rejection.
3Reliability
If conventional calibration methods are used, then measurement standards are met, but cost and implementation difficulty increase
Solution Approach 1:
The calibration process is simplified by making each device self-calibrating through its own thickness measurement. Instead of requiring complex external calibration equipment or procedures, the system measures the thickness of each device and automatically determines the calibration factor. This self-service approach reduces implementation complexity while maintaining regulatory compliance.
Solution Approach 2:
The patent changes the calibration approach from using fixed, pre-determined calibration standards to using dynamic, measurement-based calibration factors. By adjusting the calibration parameters based on actual device thickness measurements, the system achieves regulatory compliance with a simpler, more adaptable process that doesn't require complex external calibration infrastructure.
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 effectively calibrates microfluidic features in-situ, ensuring accurate measurements and tests by determining a calibration value based on the depth of the microfluidic features, thereby relaxing manufacturing tolerances and improving manufacturing yields.
Implementation Method 1
a sensor to receive reflections from capping layers disposed about the microfluidic feature in the feature layer
Data Source
AI summary
An analytical system includes a laser disposed to direct light toward a microfluidic feature disposed in a feature layer of a multiple layer test cartridge, a sensor to receive reflections from capping layers disposed about the microfluidic feature in the feature layer, and a controller to determine a depth of the microfluidic feature as a function of the received reflections.