Microfluidic Channel Fabrication with Temporary Openings and Melt Sealing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current microfabrication methods using femtosecond laser pulses face limitations in creating long, narrow channels due to etchant depletion and irregularities, particularly in transparent materials like silica, where the aspect ratio of channels is restricted, leading to incomplete or irregularly shaped structures.
Innovation Solution
A method involving the creation of temporary openings with a sealing feature that protrudes above the surface, allowing for controlled etching and subsequent sealing by melting the sealing feature to form a tight, integral seam within the substrate, enabling the fabrication of complex three-dimensional structures without the need for additional sealant materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If wet etching is used to create long channels, then channel length can be increased, but etchant depletion causes irregularities and loss of manufacturing precision
Solution Approach 1:
The etching process is segmented into multiple stages by creating intermediate temporary openings along the channel path. This allows the etching to proceed in controlled segments rather than as a single continuous process, preventing etchant depletion and maintaining uniform channel dimensions throughout the entire length.
Solution Approach 2:
Temporary openings are created preliminarily before the final channel structure is complete. These preliminary openings serve as access points for etchant delivery and allow the etching process to proceed uniformly through the entire channel length without depletion effects.
2Manufacturing precision
If temporary openings are created for etching access, then long channels can be etched uniformly, but additional sealing steps are required to close the openings
Solution Approach 1:
The sealing feature is merged with the temporary opening structure itself. The same laser processing that creates the temporary opening also creates the sealing feature (protruding rim or lip) as an integrated part of the opening, eliminating the need for separate sealing components or materials.
Solution Approach 2:
The sealing is achieved through phase transition of the substrate material. The protruding sealing feature is melted and solidified to close the temporary opening, using the substrate's own material phase changes rather than introducing external sealants.
3Ease of manufacture
If external sealant materials are used to close temporary openings, then openings can be sealed, but the seam integrity and substrate homogeneity are compromised
Solution Approach 1:
The sealing feature is made from the same substrate material as the surrounding structure, ensuring complete homogeneity. By melting and solidifying the substrate's own material to form the seal, the entire structure maintains uniform composition without foreign materials or discontinuities.
Solution Approach 2:
The substrate material itself serves as the sealing material. The protruding feature is formed from the substrate and returns to close the opening, making the substrate self-sufficient for its own sealing needs without requiring external sealants.
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
This approach facilitates the creation of long, narrow channels and complex structures with regular shapes and tight seams, overcoming the limitations of existing methods by ensuring complete closure of temporary openings and maintaining the substrate's surface integrity.
Implementation Method 1
When femtosecond light pulses are focused inside the bulk of a transparent substrate, the local instant power may be brought above the threshold of nonlinear absorption. The bulk of the material can thus be modified and functionalized without affecting its surface properties.
Implementation Method 2
the development process to reveal the unexposed regions for instance, relies on the time-dependant diffusion of wet etchants inside the material
Implementation Method 3
The purpose of the protruding features being to provide an excess of material that while melting, will feed the slit to be closed
Data Source
AI summary
A method for micro-fabricating a device on a substrate (20), comprising the steps of providing a cavity (31) having a temporary aperture (35) communicating with the outside; providing a sealing structure (45) adjacent to a perimeter of the temporary aperture (35); applying heat to the sealing structure (45), whereby the sealing structure melts and seals the temporary aperture (35).