Segmented Microfluidic Valve Prevents Membrane Rupture
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Solution Overview
Problem
In vitro models of human tissue are typically cultured in isolation, making it difficult to study systemic issues such as drug dosing, as they lack the interplay present in in vivo systems.
Innovation Solution
A cell culture system with a fluid flow plate and microfluidic valve assembly that allows for the controlled interconnection of multiple tissue types in a biomimetic environment, mimicking in vivo conditions, using a flexible membrane and actuator system to manage fluid flow and pressure, enabling precise delivery of agents like drugs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a valve assembly is used to control fluid flow in microfluidic devices, then precise fluid flow control is achieved, but fluid stagnation and pressure buildup occur leading to membrane rupture
Solution Approach 1:
The valve seat is segmented into multiple discrete contact points rather than a continuous sealing surface. This segmentation allows the membrane to deform locally at each contact point without experiencing excessive stress concentration, preventing rupture while maintaining effective flow control. The segmented design distributes mechanical stress across multiple locations along the membrane.
Solution Approach 2:
The valve head incorporates a compliant material with elastic modulus matching the membrane, creating a localized region with optimized mechanical properties. This local quality match ensures that the valve head deforms the membrane in a controlled manner that prevents stress concentration and rupture, while still achieving sufficient sealing pressure for flow control.
2Ease of operation
If the valve head contacts the membrane to close the valve, then fluid flow is blocked, but stress concentration occurs leading to membrane rupture
Solution Approach 1:
The valve seat is designed with multiple discrete contact points instead of a continuous sealing surface. This segmentation distributes the closing force across multiple locations on the membrane, preventing stress concentration at any single point while maintaining effective flow blockage when the valve is closed.
Solution Approach 2:
The valve head material is selected to have an elastic modulus that matches the membrane material. This parameter matching ensures that the valve head and membrane deform together in a compatible manner, distributing stress evenly and preventing the stress concentration that would occur with a rigid valve head.
3Force
If a rigid valve head is used to press the membrane, then valve closing force is sufficient, but membrane rupture occurs due to excessive stress
Solution Approach 1:
The valve head is constructed from a compliant material with elastic modulus matching the membrane, replacing a rigid material. This parameter change maintains sufficient closing force while distributing the applied stress across a larger area and preventing stress concentration that would lead to membrane rupture.
Solution Approach 2:
The valve assembly uses a composite approach combining the membrane material with a valve head material of matching elastic properties. This material pairing creates a mechanically compatible interface that transfers force effectively while preventing the stress concentration and rupture associated with rigid-compliant material interfaces.
4Volume of moving object
If the valve seat is positioned close to the membrane, then compact design is achieved, but fluid pressure builds up causing membrane rupture
Solution Approach 1:
The segmented valve seat design creates small gaps between discrete contact points on the membrane. These gaps act as pressure relief channels that prevent fluid pressure buildup in the valve cavity, even in a compact configuration. The segmentation allows pressure to equalize without requiring a large valve cavity volume.
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 experiments that mimic in vivo responses by allowing for the interconnection of organ systems and precise drug dosing, facilitating the study of how tissues respond to agents in a physiologically meaningful way.
Implementation Method 1
a flexible membrane including an elastomer layer
Implementation Method 2
an actuator configured to selectively control pressure applied by the valve head to the flexible membrane
Data Source
AI summary
Systems and methods disclosed herein related to an apparatus including a fluid flow plate and a microfluidic valve assembly. The fluid flow plate includes a plurality of polymer layers that define a fluid flow passage through the microfluidic valve assembly. The microfluidic valve assembly includes a valve seat, a flexible membrane, a valve cavity, a valve head, and an actuator. The actuator is configured to selectively control pressure applied by the valve head to the flexible membrane, such that in a first actuator state the valve head depresses the flexible membrane into the valve cavity and into contact with the valve seat, thereby preventing fluid flow through the valve assembly, and in a second state, the valve head and the flexible membrane are retracted substantially out of the valve cavity allowing fluid to flow through the valve assembly. In various implementations, the valve seat and/or the flexible membrane include an elastomer layer.