Acceleration-Primed Valving System for Centrifugal Microfluidics
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Solution Overview
Problem
Current centrifugal microfluidic platforms face challenges in retaining fluids at low rotational velocities and require hydrophilic surfaces for capillary action, which increases costs and complexity, and are prone to errors and high costs in manual and automated processing for clinical diagnostics.
Innovation Solution
An acceleration-primed valving system that includes a capillary valve and outlet channel, allowing fluid retention at low angular velocities without hydrophilic surfaces, using centrifugal force to control fluid flow by varying the platform's rotational speed to overcome capillary valve pressure, and employing a goose-neck shaped outlet channel to manage fluid flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capillary valves are used for fluid retention, then fluid can be retained at low rotational velocities, but hydrophilic surfaces are required which increases manufacturing complexity and cost
Solution Approach 1:
The invention changes the operational parameters by introducing controlled acceleration pulses that temporarily exceed the capillary pressure threshold, allowing fluid to pass through the valve. This transforms the valve from a static retention barrier to a dynamically controllable flow regulator, eliminating the need for hydrophilic surfaces while maintaining reliable fluid retention during normal operation.
Solution Approach 2:
The system transitions from static fluid retention to dynamic control by applying time-varying acceleration. The valve responds differently to steady-state rotation versus transient acceleration, enabling controlled fluid passage during acceleration events while maintaining retention during normal operation. This dynamic behavior replaces the need for complex surface treatments.
2Adaptability or versatility
If manual processing is used for sample analysis, then flexibility is maintained, but cost and error rates increase
Solution Approach 1:
The microfluidic system performs sample processing automatically through programmed acceleration sequences that control fluid flow through the valving system. The platform autonomously executes assay protocols without manual intervention, eliminating human error while maintaining the flexibility to run different assays by simply changing the acceleration program rather than physical reconfiguration.
3Productivity
If centrifugal force is increased to overcome capillary valve pressure, then fluid flow is enabled, but fluid retention at low velocities becomes difficult
Solution Approach 1:
The system uses periodic acceleration pulses to temporarily overcome capillary pressure and enable fluid flow. Between pulses, the system returns to low rotational velocities that maintain fluid retention. This periodic cycling between retention and flow states enables both functions without requiring continuously high centrifugal force.
Solution Approach 2:
The system applies acceleration pulses at predetermined moments in the assay protocol to prime the valving system and enable fluid flow when needed. By timing the acceleration events appropriately, the system ensures fluid moves through the system at the correct stages of the assay while maintaining retention during other stages.
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 acceleration-primed valving system effectively retains fluids at low rotational velocities, reduces the need for hydrophilic surfaces, and optimizes microfluidic processes, providing a cost-effective and error-reduced solution for sample processing in clinical diagnostics.
Implementation Method 1
manipulation of liquid properties (surface tension, density), material properties (contact angle); and geometric parameters such as the capillary dimensions and configuration of the fluids on the disc; results in well-defined rotational velocities at which capillary pressure is 'defeated' and liquid 'bursts' through passive valves
Implementation Method 2
a variety of different such means existing. These include but not limited to the use of siphoning; passive single-use valves based on surface tension effects (capillary valves, hydrophobic valves)
Implementation Method 3
As rotational velocity is decreased, capillary action may be used to imbibe the liquid within the siphon. The liquid is drawn past the U, until the liquid meniscus is at a point radially-outward of the position of the radially-inward meniscus of liquid filling the chamber
Data Source
AI summary
The invention relates to a microfluidic system for processing biological samples comprising a holding chamber adapted for holding a fluid and to be rotated on a platform, said holding chamber comprising an outlet through which fluid flow is controlled by an acceleration-primed valve system, wherein the acceleration-primed valve system comprises a capillary valve and an outlet channel. The invention provides a novel valving system, which retains fluids at low angular velocities, removes the need for hydrophilic surfaces, minimizes disc real-estate and optimizes certain microfluidic processes done in the holding chamber.