Microfluidic Pillar Trailing Angles for Gas Trapping Prevention
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Solution Overview
Problem
Microfluidic devices often face issues during priming where fluid fails to flow past the inlet due to insufficient capillary forces, leading to pinning and incomplete filling of the chamber, with air or gas pockets getting trapped at sidewalls and corners.
Innovation Solution
Incorporating pillars within the chamber with a trailing corner angle less than a threshold angle based on the fluidic contact angle, oriented to promote fluid flow from the inlet throughout the chamber, preventing air or gas trapping at sidewalls and ensuring complete filling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional chamber design is used, then device simplicity is maintained, but fluid flow is insufficient and air pockets are trapped
Solution Approach 1:
The chamber is segmented into multiple regions by introducing pillars that divide the chamber into distinct flow paths. These pillars create leading and trailing surfaces that guide fluid flow systematically through the chamber, ensuring complete filling while maintaining passive flow mechanisms.
Solution Approach 2:
The pillars are designed with asymmetric geometry, specifically with a leading surface and a trailing surface having different orientations. The trailing surface is oriented at an angle less than the fluidic contact angle, creating asymmetric capillary forces that actively pull fluid through the chamber and prevent air pocket formation.
2Productivity
If passive fluid flow is used, then device simplicity is maintained, but pinning occurs and chamber filling is incomplete
Solution Approach 1:
The pillar geometry is pre-configured with specific trailing surface angles less than the fluidic contact angle before fluid introduction. This preliminary geometric arrangement ensures that when fluid enters the chamber, capillary forces immediately act to pull fluid along the trailing surfaces, preventing pinning and promoting complete filling without requiring external actuation.
3Reliability
If chamber corners are traditional design, then manufacturing is simple, but air pockets are trapped at corners
Solution Approach 1:
The pillar trailing surfaces are specifically oriented at angles less than the fluidic contact angle at critical locations where air pockets would form. This local geometric modification at the trailing surfaces creates favorable capillary conditions precisely where needed, while the overall chamber structure remains simple and manufacturable.
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 configuration of pillars effectively enhances fluid flow, preventing pinning and air/gas pocket formation, ensuring complete chamber filling and efficient priming in microfluidic devices.
Implementation Method 1
The trailing corner has an angle less than a threshold angle that is based on a fluidic contact angle. As such, each pillar serves to pull fluid in the direction along which it is oriented.
Data Source
AI summary
A microfluidic device includes a chamber having sidewalls, a floor, a ceiling, and an inlet. The microfluidic device includes pillars extending from the floor to the ceiling of the chamber. Each pillar has an orientation relative to the inlet defined by a leading surface and a trailing corner opposite the leading corner. The trailing corner has an angle less than a threshold angle that is based on a fluidic contact angle. The orientations of the pillars relative to the inlet promote fluid flow from the inlet throughout the chamber without trapping gas at the sidewalls of the chamber.