Compliant Membrane Microfluidic Valve for Implantable Drug Delivery

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Solution Overview

Problem

Existing drug-delivery systems for long-term programmable infusion, particularly in small body parts like the inner ear, face challenges due to large size, unreliable fluid control, and sensitivity to mechanical properties, which limits their effectiveness and practicality for implantable and microfluidic applications.

Innovation Solution

Compliant membrane-based microfluidic structures provide capacitive fluidic control and valve functions, reducing system size, improving reliability, and minimizing vapor/gas permeation, by using a substrate with a compliant membrane that can be integrated with other microfluidic elements without the need for macro-scale connectors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If compliant tubing is used as a capacitive element, then fluid capacitance is provided, but system volume increases and vapor/gas permeation occurs

Engineering Contradiction:

Improvefluid capacitanceVSAvoidsystem volume

Core Design Contradiction:

Quantity of substanceVSVolume of stationary object

Solution Approach 1:

The patent uses a flexible membrane instead of compliant tubing to provide fluid capacitance. The membrane is a thin film structure that can expand and contract to store and release fluid, providing the necessary capacitance function while occupying minimal volume. This resolves the contradiction by replacing bulk tubing with a thin-film flexible structure.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent employs a pneumatic actuation system where gas pressure is used to control the flexible membrane's position and thereby control fluid flow. This allows for precise fluid control without requiring large mechanical components, maintaining small system volume while providing adequate fluid capacitance through the membrane's elastic deformation.

Inventive Principle:

Principle #29Pneumatics and hydraulics

2Adaptability or versatility

If macro-scale pumps are used for fluid control, then sophisticated control is achieved, but device size increases

Engineering Contradiction:

Improvefluid control capabilityVSAvoiddevice size

Core Design Contradiction:

Adaptability or versatilityVSVolume of stationary object

Solution Approach 1:

The patent replaces macro-scale mechanical pumps with a micro-scale system using a flexible membrane controlled by pneumatic pressure. This substitution allows for sophisticated fluid control capabilities while dramatically reducing device size, as the membrane can be integrated into a microfluidic chip structure rather than requiring external pump components.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent transitions from three-dimensional macro-scale pump components to a two-dimensional membrane structure that can be planarly integrated into the microfluidic device. This dimensional reduction enables sophisticated fluid control to be achieved within a much smaller footprint, resolving the size-capability contradiction.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Quantity of substance

If standard tubing is used with thin walls for capacitance, then capacitance value increases, but tubing length and system volume increase

Engineering Contradiction:

Improvecapacitance valueVSAvoidtubing length

Core Design Contradiction:

Quantity of substanceVSLength of moving object

Solution Approach 1:

The patent uses a thin flexible membrane to provide fluid capacitance without requiring long tubing sections. The membrane's thin film structure allows for large surface area and high capacitance value within a compact area, eliminating the need for extended tubing length while achieving the desired capacitance.

Inventive Principle:

Principle #30Flexible shells and thin films

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

These structures enable efficient and reliable fluid control in microfluidic systems, achieving small size, low permeability, and adjustable capacitance, suitable for implantable drug-delivery systems and other applications like mixing devices and chemical reactors, while maintaining fluid flow and pressure regulation.

Implementation Method 1

a compliant membrane, surrounding at least a portion of the flow-control cavity, for capacitively regulating fluid flow through the flow-control cavity

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

compliant membrane-based microfluidic structures that are capable of providing capacitive fluidic control

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 3

a bypass structure for allowing the fluid to flow through the flow-control cavity when the compliant membrane is in a collapsed position

Methodology Applied

Scientific EffectPressure Gradient: Pressure Gradient

Data Source

PatentUS9651166B2Membrane-based fluid control in microfluidic devices

Publication Date: 2017.05.16 THE CHARLES STARK DRAPER LABORATORY INC

AI summary

A microfluidic valve system includes a substrate, a valve seat a compliant membrane and a mechanically actuable displacement element. The substrate includes first and second channels embedded within it and includes a first layer of material and a second layer of material. The valve seat is in fluid communication with the first and second channels. Portions of the second layer of material form sidewalls of the second channel and the valve seat. The mechanically actuable displacement element applies a mechanical force to the compliant membrane to bring the compliant membrane into sealable contact with the valve seat, thereby closing the valve system.