Reversible Micro-Valve Using Trapped Gas for Flow Control

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Solution Overview

Problem

Existing microfluidic valves with mechanical parts face challenges in scaling to micro-scale dimensions due to fabrication difficulties and reliability issues, such as sticking and unreliability from mechanical, interfacial, and electrostatic forces.

Innovation Solution

A reversible micro-valve device utilizing thermal expansion and contraction of trapped gas in a side chamber to control fluid flow, employing capillary breaks for stabilization and a heating device to change the gas state, allowing for reliable and flexible fluid routing without moving parts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If mechanical parts are used in microfluidic valves, then flow control function is achieved, but fabrication difficulty and reliability issues increase at micro-scale dimensions

Engineering Contradiction:

Improvevalve reliabilityVSAvoidfabrication difficulty

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces mechanical moving parts with a thermal field-based control mechanism. A heating element thermally expands a polymer membrane to close the valve and thermally contracts it to open the valve, eliminating mechanical components that are difficult to fabricate and control at micro-scale dimensions. This substitution resolves the contradiction by improving reliability through elimination of mechanical sticking while maintaining ease of manufacture through standard thermal actuation techniques.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the physical state of the polymer membrane by controlling temperature parameters. The membrane transitions between expanded (closed valve) and contracted (open valve) states through thermal parameter changes. This approach avoids mechanical complexity while achieving reliable flow control, resolving the fabrication and reliability contradiction.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If mechanical parts are used in microfluidic valves, then flow control function is achieved, but mechanical sticking and unreliability from interfacial and electrostatic forces increase

Engineering Contradiction:

Improveflow control flexibilityVSAvoidvalve unreliability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent eliminates mechanical moving parts that suffer from sticking due to interfacial and electrostatic forces. Instead, it uses thermal expansion and contraction of a polymer membrane to control flow, providing ease of operation through thermal control while eliminating the reliability issues associated with mechanical contact and friction at micro-scale dimensions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If thermal expansion of trapped gas is used to control flow, then manufacturing complexity is reduced and scalability to micro-scale is improved, but device complexity for thermal control is introduced

Engineering Contradiction:

Improvemanufacturing complexityVSAvoidthermal control system complexity

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent uses the pneumatic principle of trapped gas thermal expansion and contraction to actuate the valve. The trapped gas expands when heated to push the membrane closed and contracts when cooled to allow the membrane to open. This approach reduces manufacturing complexity compared to mechanical systems while the thermal control complexity is managed through integrated heating elements and passive thermal management.

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

Enables reliable and flexible fluid control with unlimited design flexibility, scalable to micro-scale dimensions, and reduces manufacturing complexity by using thermal expansion and contraction of trapped gas to open and close fluid channels.

Implementation Method 1

A reversible micro-valve device utilizes thermal expansion and contraction of trapped gas in a side chamber to control fluid flow

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

A reversible micro-valve device utilizes thermal expansion and contraction of trapped gas in a side chamber to control fluid flow

Methodology Applied

Scientific EffectThermal contraction: Thermal Contraction

Implementation Method 3

employing capillary breaks for stabilization and a heating device to change the gas state

Methodology Applied

Scientific EffectHeating: Heating

Data Source

PatentUS12377416B2Reversible micro-valve devices

Publication Date: 2025.08.05 HEWLETT PACKARD DEVELOPMENT COMPANY LP

AI summary

A reversible micro-valve device includes a main channel, a passage comprising an opening in fluid communication with the main channel, and a side chamber to house a volume of trapped gas. The side chamber is communicably attached to the passage to control flow along the main channel. The side chamber is to be larger in volume than the main channel to which the trapped gas expands and includes one of the following two states at a given time: an open state in which the main channel is open and flow proceeds through the main channel, or a closed state in which the trapped gas within the side chamber is to expand within the passage and block the flow in the main channel.