Dynamic Particle Separation via Recirculating Flow and DEP
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Solution Overview
Problem
Existing methods for particle manipulation in microflows, such as dielectrophoresis, face challenges in efficiently and accurately separating, concentrating, and mixing small particles due to interactions with the background media, which create flow disturbances and require large electric field gradients, making it difficult to control particle trajectories effectively.
Innovation Solution
A method and apparatus that utilize a fluid-containing cell with a recurrent circulating fluid flow and a particle motivating force, which can be electrochemical, electromechanical, or mechanical, to interact with particles in a tangential orientation, allowing for separation, concentration, and mixing by controlling the fluid flow dynamics and dielectrophoretic forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If large electric field gradients are used to manipulate smaller particles via dielectrophoresis, then particle manipulation capability is improved, but flow disturbances and electro-hydrodynamic effects worsen
Solution Approach 1:
The patent applies dynamic electric field modulation at multiple frequencies to control particle trajectories. By switching between different frequency components, the system creates time-varying trapping zones that guide particles through the fluid without requiring continuously large field gradients, thereby reducing steady-state flow disturbances while maintaining manipulation precision
Solution Approach 2:
The system uses periodic electric field oscillations at fundamental and harmonic frequencies to create oscillating trapping zones. This periodic action allows particles to be captured and transported through a series of moving traps, achieving precise control with lower peak field gradients compared to static large-gradient approaches
2Manufacturing precision
If dielectrophoretic forces are used to separate particles, then separation capability is improved, but control over particle trajectories deteriorates due to background media interactions
Solution Approach 1:
The patent introduces a controlled fluid flow field as an intermediary that works in conjunction with dielectrophoretic forces. The fluid flow acts as a mediator to transport particles while the DEP forces provide lateral confinement and separation, allowing independent control of trajectory components and improving overall controllability
Solution Approach 2:
The system dynamically adjusts electric field frequency and amplitude parameters to optimize particle separation and trajectory control. By tuning the fundamental frequency and its harmonics, the system can selectively manipulate different particle sizes and properties while maintaining stable trajectories despite background media variations
3Measurement precision
If microfabricated electrodes are used to generate large electric field gradients, then submicron particle movement is achieved, but device complexity increases
Solution Approach 1:
The patent designs the electrode array to serve multiple functions: generating fundamental electric fields, creating harmonic fields through non-linear interactions, and producing fluid flow patterns. This multi-functionality allows a single electrode structure to achieve complex particle manipulation tasks that would otherwise require additional components, reducing overall device complexity
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 enables efficient separation, concentration, and mixing of particles by creating dynamic trapping zones and using time-dependent perturbations to control particle movement, improving the accuracy and efficiency of particle manipulation compared to prior art methods, and can be applied to various particle types, including submicron particles.
Implementation Method 1
Dielectric particles suspended in a dielectric media are polarized under the action of electric fields. If the field is spatially inhomogeneous, it exerts a net force on the polarized particle known as a dielectrophoretic (DEP) force
Implementation Method 2
at least one recurrent circulating fluid flow, also referred to as a 'through flow' generally aligned with the longitudinal axis within the fluid containing cell
Data Source
AI summary
Particles are separated, concentrated, or mixed within a fluid by means of a fluid-containing cell having a longitudinal axis, a cross-sectional area generally perpendicular to the longitudinal axis, and at least one particle motivating force directionally interacting with at least one recurrent circulating fluid flow generally aligned with the longitudinal axis within the fluid containing cell.