Centrifugal Microfluidic Capture Surface Orientation

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Solution Overview

Problem

Existing microfluidic devices face inefficiencies in capturing target molecules due to the 'wall effect' which repels particles from functionalized surfaces, limiting capture efficiency and assay speed, especially at higher fluid velocities.

Innovation Solution

A centrifugal microfluidic device with a capture surface oriented non-parallel to the plane of rotation, utilizing centrifugal force to direct target particles against the capture surface, independent of fluid flow rate and rotation speed, enhancing interaction and capture efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If fluid flow rate is reduced to increase capture probability, then capture efficiency is improved, but assay time increases significantly

Engineering Contradiction:

Improvecapture efficiencyVSAvoidassay time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The device performs preliminary concentration of target particles at the capture surface using centrifugal force before the actual capture assay begins. This pre-concentration step increases the local particle density at the capture surface, allowing for faster capture rates without requiring slow flow rates throughout the entire channel, thus reducing overall assay time while maintaining high capture efficiency.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If fluid velocity is increased to reduce assay time, then productivity is improved, but capture efficiency decreases due to wall effect

Engineering Contradiction:

Improveassay speedVSAvoidcapture efficiency

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The device applies centrifugal force as a counteracting force to overcome the hydrodynamic lift force (wall effect) that pushes particles away from the capture surface at high flow rates. By balancing the centrifugal force against the lift force, particles are maintained in close proximity to the capture surface even at higher velocities, enabling both fast flow rates and high capture efficiency to coexist.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The invention introduces a radial dimension (centrifugal force direction) perpendicular to the traditional flow direction to control particle-surface interaction. This additional dimensional control allows independent optimization of flow rate and capture efficiency, as the centrifugal force acts in a different dimension than the hydrodynamic lift force, enabling simultaneous high-speed flow and effective capture.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Reliability

If dielectrophoretic force is used to enhance capture, then capture efficiency is improved, but device complexity increases due to electrode arrays

Engineering Contradiction:

Improvecapture efficiencyVSAvoiddevice structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The device replaces complex electromagnetic systems (interdigitated electrodes and AC voltage sources) with a simpler mechanical centrifugal force system. The centrifugal force is generated by rotating the microfluidic device at moderate speeds, eliminating the need for complicated electrode arrays and high-frequency electrical circuits, thus reducing device complexity while maintaining effective particle capture enhancement.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

This approach decouples capture efficiency from fluid flow rate and rotation speed, allowing for faster assays and higher throughput, with improved capture efficiency and reduced operational complexity.

Implementation Method 1

A centrifugal microfluidic device with a capture surface oriented non-parallel to the plane of rotation, utilizing centrifugal force to direct target particles against the capture surface

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 2

rotating the microfluidic platform in a plane of rotation to generate centrifugal force in the device; using the centrifugal force to direct flow of the fluid to a capture surface in the device thereby pushing the target particle against the capture surface

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentUS9442108B2Centrifugally-enhanced capture method and device

Publication Date: 2016.09.13 NAT RES COUNCIL OF CANADA

AI summary

In a centrifugal microfluidic device for conducting capture assays, a microfluidic platform rotates in a plane of rotation and has at least one capture surface for immobilizing a target particle of interest in the device. The capture surface oriented so that it is not parallel to the plane of rotation of the device and is positionally fixed in the device during operation of the device. The centrifugal force arising from rotation of the device forces the target particles against the capture surface. Capture efficiency is independent of the rate of flow of the fluid and independent of the rate of rotation of the microfluidic platform.