Microfluidic Circuit Element with Nano Interstices
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Solution Overview
Problem
Conventional microfluidic devices using the capillary flow method face challenges in maintaining stable fluid flow due to poor surface wettability of plastic materials, which requires additional surface treatments like chemical or plasma treatments, making mass production difficult and long-term stability uncertain.
Innovation Solution
A microfluidic circuit element is designed with nano interstices on both sides of the channel, formed by joining substrates using solvents, heat, pressure, or laser beams, allowing capillary-driven fluid flow without the need for surface treatments, and fabricated using materials like silicon, glass, or plastic with controlled nano interstice dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If surface treatment methods (corona, surface coating, plasma treatment) are used to improve wettability, then fluid flow is enhanced, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The invention introduces nano-interstices (porous structures) into the microfluidic channel walls to enhance capillary action and improve fluid flow. These nano-interstices provide increased surface area and capillary forces that promote spontaneous fluid movement without requiring complex surface treatment processes like corona or plasma treatment.
Solution Approach 2:
The invention transitions from two-dimensional surface treatment to three-dimensional nano-structure integration by embedding nano-interstices within the channel walls. This dimensional change allows the channel to generate capillary forces internally through vertical nanostructures rather than relying on surface-level treatments, thereby simplifying the overall device fabrication process.
2Reliability
If surface treatment methods are applied to enhance wettability, then initial fluid flow is improved, but long-term flow stability deteriorates due to treatment degradation
Solution Approach 1:
The nano-interstices are integrated directly into the channel wall structure, enabling the channel to self-generate capillary forces for fluid movement without requiring external surface treatment maintenance. This self-service mechanism ensures long-term flow stability as the nano-structures remain permanently embedded in the channel walls, preventing degradation over time.
Solution Approach 2:
The nano-interstices are pre-formed within the channel walls during fabrication, establishing permanent capillary structures before the device is put into service. This preliminary action ensures that the channel walls inherently possess the ability to generate sustained capillary forces throughout the device's operational life, eliminating the need for subsequent surface treatments that would degrade over time.
3Ease of manufacture
If conventional plastic materials are used for microfluidic channels, then ease of fabrication is maintained, but surface wettability remains unacceptably low
Solution Approach 1:
The invention maintains the use of conventional plastic materials for channel fabrication while introducing nano-interstices into the channel walls to enhance wettability. The plastic material provides ease of fabrication through standard molding techniques, while the embedded nano-structures provide the necessary capillary action and surface wettability, combining the advantages of both approaches.
Solution Approach 2:
The invention creates a composite structure by combining conventional plastic channel walls with integrated nano-interstice structures. This composite approach allows the device to maintain the manufacturing advantages of plastic materials while incorporating the enhanced wettability and capillary properties of nano-structured surfaces, achieving both ease of manufacture and improved reliability.
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 microfluidic circuit element achieves stable and efficient fluid flow over a long period without additional surface treatments, facilitating easy fabrication and maintaining high flow stability, even with sub-hydrophobic surface contact angles, enhancing the reliability of microfluidic devices.
Implementation Method 1
The capillary flow method, in particular, which uses capillary force spontaneously occurring in microchannels is advantageous because a very small amount of a fluid moves spontaneously and instantly along specific channels without the use of an additional driving means.
Implementation Method 2
In order to achieve a satisfactory flow of a fluid in the conventional microfluidic device using the capillary flow method, the surface wettability of the capillary wall must be good.
Data Source
AI summary
A microfluidic circuit element comprising a microfluidic main channel and nano interstices is disclosed. The nano interstices are formed at both sides of the main channel and are in fluid communication with the main channel. The nano interstices have a height less than that of the main channel, gives more driving force of the microfluidic channel and provides stable flow of a fluid. The microfluidic circuit element may be made from a plastic material having a contact angle of 90 degrees or less. The microfluidic circuit element is particularly useful when filling a liquid sample to the channel which is empty or filled with air and shows greatly improved a storage stability.