Embedded Rotary Micro Pump for Viscous Fluid Handling
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Solution Overview
Problem
Conventional micro fluidic pumps face challenges in efficiently handling fluids of varying viscosities and properties, particularly in micro channels, due to dominance of viscous forces over inertial ones, and limitations of existing technologies such as electrowetting and electroosmotic pumps which fail with non-conducting liquids and biological samples.
Innovation Solution
A micro rotary pumping system utilizing an external rotating magnetic field to create shear in fluids within micro channels through an embedded and sealed annular disk, generating continuous and steady fluid flow regardless of fluid viscosity or properties, by rotating the disk within a micro channel to induce boundary shear stress and velocity gradient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If electrowetting or electroosmotic pumps are used for fluid handling in micro channels, then continuous-flow micro fluidics and droplet handling are achieved, but the efficiency highly depends on fluid's surface tension properties, viscosity and electrical conductivity
Solution Approach 1:
The patent replaces electrical field-based pumping mechanisms (electrowetting, electroosmosis) with a magnetic field-based mechanical rotation system. A rotating magnetic field drives a magnetic rotor that mechanically shears the fluid through a gap, generating flow independent of fluid electrical properties. This substitution resolves the contradiction by eliminating dependence on surface tension and conductivity while maintaining continuous flow capability.
Solution Approach 2:
The patent changes the driving parameter from electrical field strength to magnetic field rotation speed. By controlling the rotation speed of the magnetic field (and thus the rotor), the flow rate can be continuously adjusted. This parameter change allows the system to handle fluids of varying viscosities and electrical properties uniformly, as the mechanical shear force directly overcomes viscous resistance without electrical property constraints.
2Productivity
If external pumps such as pressure, vacuum, or syringe pumps are used to induce continuous flow, then steady flow rates are achieved, but connections to external pumps must be removed and on-chip pumps must be fabricated
Solution Approach 1:
The patent merges the pump function directly into the microfluidic chip structure by integrating a magnetic rotor within a closed chamber that is part of the fluid pathway. This integration eliminates the need for external pump connections while maintaining continuous flow capability. The magnetic rotor is positioned such that its rotation directly shears fluid through the channel, combining pumping and fluid handling in a single integrated component.
Solution Approach 2:
The patent introduces a magnetic rotor as an intermediary element between the external magnetic field source and the fluid. The rotor converts external magnetic field energy into mechanical rotation, which then mechanically shears the fluid. This intermediary mechanism allows continuous flow generation without requiring direct mechanical or fluid connections to external pumps, simplifying chip integration.
3Productivity
If conventional mechanical actuators are used for pumping in micro channels, then pumping action is achieved, but viscous forces dominate inertial ones at sub-millimeter scales causing failure
Solution Approach 1:
The patent employs continuous rotational motion of the magnetic rotor, which creates continuous shear stress on the fluid boundary. This persistent mechanical action at the micro-scale overcomes the dominance of viscous forces by maintaining a steady velocity gradient across the channel. The rotational mechanism ensures that inertial effects are continuously generated through the rotating magnetic field, preventing the pump from failing due to viscous dominance.
Solution Approach 2:
The patent uses a dynamic rotating magnetic field that continuously changes direction and magnitude to drive the rotor. This dynamic excitation creates ongoing shear forces that adapt to the fluid's viscous characteristics. The rotational motion transforms the static viscous resistance into a manageable dynamic interaction, allowing reliable pumping even when viscous forces dominate at micro-scales.
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 system efficiently pumps all fluids, including those with high viscosity, without depending on fluid properties, achieving continuous and laminar flow with minimal noise and pulsation, suitable for microprocessor cooling and biochips, with adjustable flow rate through varying disk rotation speed.
Implementation Method 1
A magnetic material affixed to the annular disk and magnetically coupled to the external rotating magnetic field for rotating the annular disk to create a shear in the fluid in the micro channel for pumping the fluid
Implementation Method 2
rotating the annular disk to create a shear in the fluid in the micro channel for pumping the fluid thereby
Data Source
AI summary
A micro pumping mechanism is proposed to generate flow in micro channels of micro fluidic devices and three dimensional microprocessors cooled by the flow of coolant fluids. The proposed micro pump comprises a rotating disk inside a chamber, which overlaps with the fluidic micro channel. The rotating disk induces a shear flow across the micro channel, transporting fluid elements in the direction of the rotation of the disk. The disk can be rotated by external magnetic or electric fields as in direct drive, induction, or electrostatic motors.