Magnetic Impeller Liquid Delivery for Stable Flow Direction
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Solution Overview
Problem
Existing liquid delivery devices for Microphysiological Systems (MPS) experience unstable liquid flow direction and flow rate due to the gap between the support portion of the liquid delivery chamber and the impeller, leading to variations in liquid delivery state over time.
Innovation Solution
A liquid delivery device with a magnetic impeller supported by a support shaft, where the impeller rotates with a biased gap between the support shaft and annular portion, and is driven by a motor outside the chamber, ensuring consistent flow direction and stable flow rate through precise alignment of flow paths and impeller rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a gap is provided between the support portion and the impeller to enable smooth rotation, then the impeller can rotate smoothly, but the contact point changes each rotation causing unstable flow direction and flow rate
Solution Approach 1:
The patent applies asymmetry by making the gap between the support portion and impeller non-uniform. Specifically, the gap is designed to be smaller at the inlet side and larger at the outlet side of the impeller. This asymmetric gap configuration creates a preferred contact position that stabilizes the rotation center, preventing the circular movement of the rotation center that occurs with symmetric gaps, thereby maintaining constant flow direction and stable flow rate while still allowing smooth rotation.
2Reliability
If the gap is minimized to eliminate contact point variation, then flow stability improves, but the impeller cannot rotate smoothly and manufacturing difficulty increases
Solution Approach 1:
The patent applies local quality by creating different gap sizes at different locations around the impeller perimeter. The gap is locally smaller at the inlet side where contact is needed for stability, and locally larger at the outlet side where clearance is needed for smooth rotation. This localized variation in gap quality achieves both stable rotation (through consistent contact at the inlet) and smooth operation (through adequate clearance at the outlet), while being manufacturable with standard tolerances.
3Reliability
If a bearing is provided in the gap to smooth rotation, then rotation stability improves, but the device complexity increases and mass production becomes difficult
Solution Approach 1:
The patent replaces the mechanical bearing system with a magnetic field-based drive system. Instead of using physical contact bearings that would add complexity and require precise assembly, the invention uses a magnetic drive mechanism where a magnet in the support portion interacts with a ferromagnetic material in the impeller. This non-contact magnetic coupling provides rotation stability without mechanical friction or wear, eliminates the need for complex bearing structures, and simplifies mass production by removing delicate mechanical components.
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 device achieves continuous liquid delivery with a constant flow direction and stable flow rate, suitable for mass production and use in cell culture applications.
Implementation Method 1
a drive motor that is arranged outside the liquid delivery chamber and rotates the impeller by a magnetic field
Data Source
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AI summary
Provided is a liquid delivery device that is capable of continually delivering liquid in a constant liquid flow direction at a stable flow rate. A liquid delivery device (100) comprises a liquid delivery unit (3) and a liquid delivery rotary unit (8). The liquid delivery unit (3) comprises: a liquid delivery chamber (7) where liquid flows in and flows out; and a first straight flow channel (11) and a second straight flow channel (12) that allow liquid to circulate through the liquid delivery chamber (7). The liquid delivery rotary unit (8) comprises: a spindle (7b) that is disposed so as to protrude at the center of the liquid delivery chamber (7); an impeller (20) that is supported by an annular part (21) so as to be rotatable about the spindle (7b) and that contains a magnetic material; and a drive motor (31) that is disposed outside the liquid delivery chamber (7) and that causes the impeller (20) to be rotated by magnetic fields. A gap (24) is provided between the outer circumference (7c) of the spindle (7b) and the inner circle (21a) of the annular part (21). The drive motor (31) is disposed such that the impeller (20) is allowed to rotate in a state where the gap (24) is biased relative to a range of contact between the outer circumference (7c) of the spindle (7b) and the inner circle (21a) of the annular part (21).