Microfluidic Dispensing Device Diaphragm Backpressure Control
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Solution Overview
Problem
Existing microfluidic dispensing devices face challenges in maintaining backpressure and preventing fluid separation, especially in designs with capillary members like foam or felt, where re-mixing settled fluid is difficult, and in free fluid style printheads with spring-loaded movable walls, where maintaining consistent backpressure is intricate.
Innovation Solution
A microfluidic dispensing device with a lid-body split design featuring a diaphragm that engages the interior perimetrical wall of the body, creating a fluid chamber with a dome portion that collapses to maintain backpressure and includes a stir bar for fluid mixing, ensuring effective fluid distribution and prevention of separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a capillary member (foam or felt) is used to control backpressure, then backpressure is maintained, but fluid separation occurs and re-mixing is almost impossible
Solution Approach 1:
The patent uses a flexible diaphragm (thin film) instead of a capillary member to control backpressure. The diaphragm is positioned at the rear of the fluid chamber and deforms under pressure to maintain backpressure while allowing fluid to remain in a free state, preventing separation and enabling re-mixing through the magnetic stir bar.
Solution Approach 2:
The patent replaces the mechanical capillary structure with a magnetic field-based stirring system. A magnetic stir bar positioned in the fluid chamber can rotate to mix fluid that may have settled, providing a mechanism to restore homogeneity without requiring physical access to the fluid.
2Stress or pressure
If a spring-loaded movable wall with deformable bladder is used, then backpressure is maintained through deflection, but the design complexity increases and the bladder collapses on itself
Solution Approach 1:
The patent extracts the spring-loaded bladder mechanism from the design and replaces it with a simpler diaphragm system. The diaphragm is directly engaged with the fluid chamber and uses its own flexibility to maintain backpressure, eliminating the need for separate springs, movable walls, and complex assembly structures.
Solution Approach 2:
The patent employs a flexible diaphragm as the primary backpressure control element. This thin film structure deforms in response to fluid pressure changes, providing backpressure control through its inherent elasticity rather than requiring external spring mechanisms or complex movable wall assemblies.
3Reliability
If the diaphragm is positioned with its sealing rim parallel to the printhead chip, then the ink enclosure is properly formed, but the deflection axis is constrained
Solution Approach 1:
The patent positions the diaphragm's deflection axis perpendicular to the printhead chip plane, utilizing the vertical dimension of the fluid chamber. This allows the diaphragm to deflect upward or downward to accommodate pressure changes while maintaining its sealing rim parallel to the chip, effectively using three-dimensional space to resolve the constraint.
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 effectively maintains a consistent backpressure and prevents fluid separation, ensuring reliable fluid dispensing by using a diaphragm that collapses to adjust volume and a stir bar for mixing, enhancing the operational efficiency and stability of the microfluidic system.
Implementation Method 1
a dome portion that collapses to maintain backpressure
Implementation Method 2
includes a stir bar for fluid mixing, ensuring effective fluid distribution and prevention of separation
Data Source
Figure 1~2
Figure 3~5
Figure 6
AI summary
A fluidic dispensing device (110) is provided, comprising a body (122) including a base wall (138) having an exterior base surface (214), an interior perimetrical wall (150) that has a perimetrical end surface (150-3) and extends from the base wall to define a chamber (148); an ejection chip (118) mounted to a chip mounting surface (140-2) of the body, where the chip mounting surface defines a first plane (142); a diaphragm (130) engaged with the perimetrical end surface; and a lid (124) attached to the body, with the diaphragm interposed between the lid and the body, the body and the lid defining a split at a juncture of the lid and the body.