Microfluidic Cartridge Passive Mixing Kinetic Assays
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current microfluidic devices face challenges in performing multiple clinical assays on small sample volumes, particularly in pediatric blood samples with high hematocrit, due to difficulties in mixing reagents and analytes homogeneously, which limits kinetic assays and requires substantial sample or reagent volumes, and existing solutions are not effective for passive mixing in minimal sample volumes.
Innovation Solution
A microfluidic cartridge with sub-microliter reaction chambers made from an ACA layer between transparent films, using suction pressure for reagent dissolution and passive mixing through convective eddy diffusion and molecular diffusion, allowing for zero-order kinetics and rapid reagent homogenization without mechanical mixing, enabling kinetic assays in small volumes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If mechanical vibratory means or ultrasonic mixing is used to achieve homogeneous mixing in microfluidic chips, then mixing homogeneity is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces mechanical vibratory mixing systems with a passive mixing approach utilizing fluid dynamics principles. The microfluidic channel geometry and flow conditions are designed to create turbulent mixing patterns without requiring external mechanical actuators, thereby achieving homogeneous mixing while reducing device complexity
Solution Approach 2:
The system uses the sample flow itself to drive the mixing process through carefully designed channel geometries that exploit the sample's kinetic energy and flow characteristics. The mixing is achieved self-service style by allowing the fluid flow to create its own mixing patterns through turbulence and eddy formation, eliminating the need for separate mixing mechanisms
2Quantity of substance
If sub-microliter reaction volumes are used to reduce sample consumption, then sample volume is reduced, but mixing difficulty and time increase
Solution Approach 1:
The patent addresses the mixing time issue in sub-microliter volumes by transitioning from three-dimensional bulk mixing to two-dimensional surface-driven mixing at the microfluidic channel interfaces. The flow is designed to create turbulent patterns and eddies at the channel walls and interfaces, which dramatically accelerates mixing in such small volumes compared to conventional bulk mixing approaches
3Device complexity
If endpoint assays are used to simplify device design, then device complexity is reduced, but assay versatility and kinetic analysis capability are limited
Solution Approach 1:
The patent enables kinetic assay capability by making the measurement system dynamically responsive to real-time changes in the reaction mixture. The microfluidic system allows continuous monitoring of reaction progress through optical detection, and the data acquisition system can capture kinetic profiles by measuring absorbance or other signals at multiple time points, thereby enabling both endpoint and kinetic assay modes
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 cartridge achieves consistent assay results with zero-order kinetics for clinical analytes within 5 to 60 seconds, conserving sample and allowing multiple assays from a single sample, with diffusional and osmotic convective eddy mixing ensuring optical homogeneity and steady-state reaction conditions.
Implementation Method 1
Each reaction chamber is cut from an ACA layer laminated between two optically transparent films enclosing the chamber, the transparent films forming optical windows for transillumination of the sample. The sample is urged into the reaction chamber by application of a downstream suction pressure under stop flow conditions.
Implementation Method 2
Convective eddy diffusion and molecular diffusion drive rapid dissolution of the reagents to optical homogeneity.
Implementation Method 3
Convective eddy diffusion and molecular diffusion drive rapid dissolution of the reagents to optical homogeneity.
Implementation Method 4
Accumulation or disappearance of a reaction product such as NADH or a formazan is monitored spectrophotometrically through the optical windows.
Data Source
AI summary
A microfluidic cartridge including on-board dry reagents and microfluidic circuitry for determining a clinical analyte or analytes from a few microliters of liquid sample; with docking interface for use in a host workstation, the workstation including a pneumatic fluid controller and spectrophotometer for monitoring analytical reactions in the cartridge.