Microfluidic Bubble Valve Using a Pinch Point for Reliable Flow Shutoff

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Solution Overview

Problem

Existing microfluidic valves face reliability issues and fabrication complexities due to their reliance on moving parts such as flexible flaps and free-flowing solid plugs, making them unreliable and difficult to manufacture.

Innovation Solution

The development of microfluidic devices utilizing a bubble forming device, like a heater, and a pinch point in a channel, where a bubble is created to block the channel when closed and eliminated to open, providing a reliable and simpler fabrication method.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If moving parts such as flexible flaps and free-flowing solid plugs are used in microfluidic valves, then the valve can control liquid flow, but the device becomes unreliable and difficult to manufacture

Engineering Contradiction:

Improvevalve reliabilityVSAvoidmoving parts complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces mechanical moving parts (flexible flaps, solid plugs) with a bubble-based occlusion mechanism. A bubble is introduced into the microchannel to block liquid flow, eliminating the need for mechanical components. The bubble is generated by injecting gas through a valve or by heating the liquid to create vapor bubbles, and it is removed by applying a pressure pulse or by dissolving it in a solvent.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses gas injection to create bubbles that occlude the microchannel. Gas is introduced through a gas injection port or by sparging, creating a bubble that blocks the liquid flow path. The bubble can be controlled to move along the channel and be removed by pressure pulses or solvent dissolution, providing valve functionality without mechanical parts.

Inventive Principle:

Principle #29Pneumatics and hydraulics

2Ease of manufacture

If moving parts are used in microfluidic valves, then flow control is achieved, but fabrication becomes complex and difficult

Engineering Contradiction:

Improvevalve fabrication easeVSAvoidmoving parts complexity

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent replaces mechanical moving parts with a bubble-based occlusion mechanism. A bubble is introduced into the microchannel to block liquid flow, eliminating the need for mechanical components. The bubble is generated by injecting gas through a valve or by heating the liquid to create vapor bubbles, and it is removed by applying a pressure pulse or by dissolving it in a solvent.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If a bubble-based mechanism is used, then reliability and fabrication ease are improved, but a new mechanism must be implemented

Engineering Contradiction:

Improvevalve reliabilityVSAvoidmechanism adaptability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent changes the physical state of the liquid by heating it to create vapor bubbles for occlusion. A heater element is used to locally heat the liquid in the microchannel, causing it to vaporize and form a bubble that blocks flow. The bubble is removed by cooling the liquid or by applying a pressure pulse, providing a thermally-controlled valve mechanism.

Inventive Principle:

Principle #35Parameter changes

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 solution enhances the reliability and ease of fabrication of microfluidic valves by using a bubble-based mechanism that effectively occludes or opens the valve, improving control and reducing the complexity associated with moving parts.

Implementation Method 1

a heater within the channel... activate the heater so as to form a bubble

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 2

form a bubble sized so as to be captured by the pinch point in the channel to occlude the channel

Methodology Applied

Scientific EffectVaporization: Evaporation

Implementation Method 3

pinch point in the channel between the heater and the liquid receiver... captured by the pinch point

Methodology Applied

Scientific EffectCapillary pressure: Capillary Pressure

Data Source

PatentUS11389795B2Bubble valve

Publication Date: 2022.07.19 HEWLETT PACKARD DEVELOPMENT COMPANY LP

AI summary

A microfluidic device may include a valve located between a liquid source and a liquid receiver. The valve may include a channel connecting the liquid source to the liquid receiver, a heater within the channel, and a pinch point in the channel between the heater and the liquid receiver. The microfluidic device may include a controller to activate the heater so as to form a bubble sized so as to be captured by the pinch point in the channel to occlude the channel.