Microfluidic Loading Well with Sloped Bottom and Off-Center Inlet

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Solution Overview

Problem

Existing microfluidic devices face issues with sample loss and dead volumes during loading, particularly when working with rare samples, due to inefficient geometries that do not prevent sample wasting and contamination.

Innovation Solution

A microfluidic chip with a loading well design featuring a sloped bottom and an off-center inlet port, partially filled with a continuous phase of higher density oil, which minimizes dead volume and optimizes droplet formation and stability, allowing for precise control over droplet placement and movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If a conventional loading well geometry is used, then the device structure is simple, but sample loss and dead volume increase

Engineering Contradiction:

Improvesample lossVSAvoidwell geometry complexity

Core Design Contradiction:

Loss of substanceVSDevice complexity

Solution Approach 1:

The loading well incorporates a curved surface design where the bottom surface is convex relative to the well cavity, creating a spherical or dome-like shape. This curvature prevents sample adhesion to flat surfaces and eliminates dead volumes, allowing complete sample transfer into droplets without loss.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The inlet port is positioned off-center relative to the well cavity, creating an asymmetric geometry that optimizes sample flow dynamics. This asymmetric placement, combined with the curved bottom surface, ensures efficient sample collection and minimizes residual volumes that would otherwise remain trapped in conventional symmetric designs.

Inventive Principle:

Principle #4Asymmetry

2Productivity

If the inlet port is centered, then the device structure is symmetric and simple, but sample loading efficiency decreases

Engineering Contradiction:

Improvesample loading efficiencyVSAvoidinlet port positioning

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The inlet port is deliberately positioned off-center within the loading well, creating an asymmetric configuration that enhances sample flow dynamics. This asymmetric placement optimizes the path of sample entry and improves loading efficiency by preventing stagnant zones and ensuring complete sample uptake into droplets.

Inventive Principle:

Principle #4Asymmetry

3Loss of substance

If a flat bottom well is used, then manufacturing is simpler, but dead volume increases and sample is wasted

Engineering Contradiction:

Improvesample wastingVSAvoidwell fabrication

Core Design Contradiction:

Loss of substanceVSEase of manufacture

Solution Approach 1:

The loading well features a convex curved bottom surface instead of a flat bottom, creating a spherical or dome-like geometry. This curved design eliminates dead volumes where sample could be trapped, ensuring complete sample transfer. The curvature can be manufactured using standard molding or machining techniques, making the increased complexity acceptable given the elimination of sample waste.

Inventive Principle:

Principle #14Spheroidality (Curvature)

4Productivity

If droplets are placed far from the inlet port, then droplet stability is improved, but sample loading distance increases and efficiency decreases

Engineering Contradiction:

Improvedroplet formation speedVSAvoiddroplet stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The curved bottom surface and off-center inlet port are designed to guide and focus the sample flow directly toward the optimal droplet formation location. This preliminary positioning of the sample ensures that droplets form at the ideal distance from the inlet port, simultaneously achieving fast formation and stable placement without requiring additional adjustment steps.

Inventive Principle:

Principle #10Preliminary action

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 design reduces sample wasting, enhances assay accuracy and reproducibility, and maintains droplet integrity during thermal cycling, enabling efficient nucleic acid amplification and analysis.

Implementation Method 1

partially filled with a continuous phase of higher density oil

Methodology Applied

Scientific EffectDensity gradient: Density Gradient

Implementation Method 2

allowing for precise control over droplet placement and movement

Methodology Applied

Scientific EffectFluid flow:

Implementation Method 3

the wall comprises a bottom wall part globally extending according to a bottom plan parallel to the base plan (x/y) and a lateral wall part extending along a well lateral direction disposed according to an angle 80° to 105° relatively to the bottom plan

Methodology Applied

Scientific EffectGravitation: Gravitation

Data Source

PatentUS20210394188A1Wells for optimized sample loading in microfluidic chips

Publication Date: 2021.12.23 STILLA TECH

AI summary

The present invention relates to a loading well (320) comprising a lateral wall part (3211) in cross-section parallel to the base plan (x/y) and/or a bottom wall part comprising at least one sloped bottom section (32121). The present invention also relates to a microfluidic chip comprising the same; systems comprising the same configured to reduce the dead volume of a drop of sample to be loaded in the microfluidic chip and/or to trap a drop in a defined location; and methods using the same.