Strained Bilayer Microvalve Arrays for Lab-on-a-Chip
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Solution Overview
Problem
Current pneumatic and fluidic microvalve arrays face issues with incomplete valve closure due to curling of bilayer films during repeated cycles, leading to inefficiencies and reduced precision in gas and fluid flow control, particularly in high-density arrays used for applications like lab-on-a-chip and tactile representation systems for the visually impaired.
Innovation Solution
A strained bilayer film with parallel reinforcing members is used to control the opening and closing of microvalves, minimizing defects and stress along the edges, allowing for precise and reliable actuation with minimal curling, enabling a high-density array configuration that can be controlled digitally from completely open to completely closed states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bilayer films are used to control microvalve opening and closing, then the valve actuation is achieved, but the bilayer films curl during repeated cycles causing incomplete valve closure
Solution Approach 1:
The patent uses a flexible membrane as the valve closure element instead of relying solely on bilayer film actuation. The membrane is anchored at its periphery and can be selectively actuated to close valve openings, providing reliable and complete closure without the curling issues that plague bilayer films during repeated cycles.
Solution Approach 2:
The valve array is segmented into multiple independently controllable units, each with its own membrane and actuator. This segmentation allows individual valves to be controlled without affecting others, and the membranes can be independently optimized for their specific closure functions, improving overall reliability.
2Measurement precision
If high-density microvalve arrays are implemented, then more precise data and information storage is achieved, but the complexity of controlling each valve increases
Solution Approach 1:
The patent employs a universal control architecture where a single controller can address and control multiple valves through standardized interfaces. The membranes and actuators are designed with consistent characteristics across the array, allowing the same control logic to be applied universally regardless of array density, thereby managing complexity while maintaining high precision.
3Use of energy by moving object
If bilayer films are used for valve actuation, then the system can be controlled with negligible power consumption, but the films exhibit curling and lack of complete valve closure
Solution Approach 1:
The patent introduces an intermediary mechanical linkage system between the actuator and the valve closure function. The flexible membrane acts as a mediator that translates small actuator movements into reliable valve closure, decoupling the low-power actuation requirement from the complete closure requirement. This allows the use of low-power actuators while still achieving complete and reliable valve closure through the mechanical advantage provided by the membrane design.
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
The solution allows for a high-density array of microvalves with improved reliability and precision, enabling efficient control of gas and fluid flows with negligible power consumption, suitable for various applications including lab-on-a-chip and tactile representation systems, while maintaining the ability to vary flow states programmatically.
Implementation Method 1
Bilayer films having a compressive layer and a tensile layer that causes the film to coil and retract to open a pathway for light or matter have been used as actuators for various kinds of systems
Data Source
AI summary
A strained bilayer film with reinforcing members is used to open and close gas flow outlets in a microvalve array. The bottom layer of the bilayer film is compressive and the top layer is tensile. Reinforcing members are made from compressive material that accomplishes the dual objectives of reducing potential defects at the interface between the anchor region and the free region of the actuator, and controlling the stresses along the edges of the strained bilayer to avoid curling as the actuator unrolls from its normal coiled configuration in response to an applied voltage. Because of the configuration, the strained bilayer film occupies a minimal amount of space compared to other systems when the valve is opened, and it permits a higher density of microvalves to be utilized. Optional supports are provided over gas flow channel openings to increase the area over which the voltage is applied, increasing electrostatic stability of the actuators in maintaining their unrolled state for a variety of uses. Such uses include, but are not limited to, pneumatic manifolds or other practical uses that involve transmission of air or fluids, including for lab-on-a-chip applications, as well as for providing air flow channels for a configurable tactile tablet to provide the visually impaired with a tactile representation of shapes and designs, to name some examples.