Fluidic Dispensing Device Stir Bar Mixing

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Solution Overview

Problem

Microfluidic dispensing devices with compact designs, incorporating both a fluid reservoir and an on-board fluid ejection chip, face challenges in remixing fluids near the ejection chip to prevent clogging due to particulate settling, which existing agitation methods in remote tanks do not effectively address.

Innovation Solution

A fluidic dispensing device with a housing containing a chamber and an ejection chip, featuring a fluid channel and a stir bar that rotates to create fluid mixing and redistribution within the reservoir, ensuring uniform fluid distribution to the ejection chip, thereby minimizing particulate settling and clogging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a compact design with on-board fluid reservoir and ejection chip is used, then device size is reduced, but particulate settling and clogging near the ejection chip occurs

Engineering Contradiction:

Improvedevice sizeVSAvoidclogging prevention

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent introduces a movable stir bar that rotates within the fluid channel to dynamically mix the fluid and prevent particulate settling. This dynamic element transforms the static compact design into an active system that continuously agitates the fluid, resolving the clogging issue without increasing device volume.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The fluid channel is segmented into distinct regions including a reservoir, a mixing zone with the stir bar, and an ejection zone. This segmentation allows targeted mixing action in the mixing zone while maintaining compact overall design, preventing particulates from settling in the ejection region.

Inventive Principle:

Principle #1Segmentation

2Stability of the object's composition

If remote tank agitation is used, then bulk fluid mixing is achieved, but remixing near the ejection chip is insufficient

Engineering Contradiction:

Improvebulk fluid mixingVSAvoidejection chip region remixing

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The stir bar is positioned specifically within the fluid channel adjacent to the ejection chip, creating localized intense mixing in the critical region. This local quality approach ensures that the ejection chip area receives adequate remixing while the bulk reservoir maintains its composition stability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The fluid channel acts as an intermediary zone between the bulk reservoir and the ejection chip. The stir bar operates in this intermediate region to remix fluid before it reaches the ejection chip, bridging the gap between bulk mixing and localized ejection needs.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If fluid velocity is increased to prevent settling, then mixing efficiency improves, but pressure loss increases

Engineering Contradiction:

Improvemixing efficiencyVSAvoidpressure loss

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The rotating stir bar introduces mechanical vibration and turbulence into the fluid, enhancing mixing efficiency through shear forces and chaotic flow patterns. This mechanical agitation achieves effective mixing at lower bulk flow velocities, reducing pressure losses compared to high-velocity flow alone.

Inventive Principle:

Principle #18Mechanical vibration

Solution Approach 2:

The system utilizes hydraulic principles by employing a rotating stir bar that creates localized fluid circulation and mixing zones. This hydraulic mixing mechanism achieves efficient particulate suspension through rotational motion and shear stress, avoiding the need for high-velocity bulk flow that would cause excessive pressure drops.

Inventive Principle:

Principle #29Pneumatics and hydraulics

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 remixes fluids near the ejection chip, preventing clogging and ensuring consistent fluid ejection by utilizing a rotating stir bar to generate shear stress and distribute particles within the fluid channel, maintaining fluid uniformity and flow efficiency.

Implementation Method 1

utilizing a rotating stir bar to generate shear stress and distribute particles within the fluid channel

Methodology Applied

Scientific EffectShear stress: Shear Stress

Implementation Method 2

featuring a fluid channel and a stir bar that rotates to create fluid mixing and redistribution within the reservoir

Methodology Applied

Scientific EffectRotational motion:

Data Source

PatentUS9751315B1Fluidic dispensing device having flow configuration

Publication Date: 2017.09.05 BRADY WORLDWIDE INC

AI summary

A fluidic dispensing device includes a housing having an exterior wall and a chamber. The exterior wall has a chip mounting surface defining a first plane and having an opening. The chamber has an interior space. The chamber has an inlet port and an outlet port, the inlet port being separated a distance from the outlet port. An ejection chip is mounted to the chip mounting surface of the exterior wall. The ejection chip is in fluid communication with the opening. A fluid channel is formed in the housing that is in fluid communication with each of the opening, the inlet port, and the outlet port.