Ceramic Microfluidic Threads Formed With a Graphite Insert
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Forming complex structures like screw threads within refractory materials such as ceramics for microfluidic modules is challenging due to high costs, material brittleness, and significant shrinkage during firing, which complicates machining and requires expensive diamond tools and special machinery.
Innovation Solution
A method involving a green-state refractory material structure with a removable graphite insert having a negative surface of the desired shape, which is machined into the ceramic body, fired together, and then removed to form internal threads, allowing for the direct screwing of metallic couplers into the ceramic microreactor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional machining methods are used to form screw threads in fired ceramic bodies, then manufacturing precision can be achieved, but device complexity and cost increase due to requiring diamond tools and special machinery
Solution Approach 1:
The patent applies preliminary action by forming the threaded structure in the green state (before firing) using a mandrel inserted into the ceramic body. The mandrel is positioned and secured while the ceramic is still soft and workable, allowing thread formation without requiring complex diamond machining equipment after firing. This preliminary formation of the threaded structure resolves the contradiction by achieving precision through pre-positioning rather than post-firing machining.
Solution Approach 2:
The patent utilizes parameter changes by exploiting the difference in physical state of the ceramic material between green state and fired state. In the green state, the ceramic is soft and deformable, allowing easy mandrel insertion and thread formation. After firing, the ceramic becomes hard and dimensionally stable, preserving the threaded structure. This parameter change allows simple tooling to achieve precise threads without requiring complex machining equipment.
2Ease of manufacture
If green-state machining is used to form threads, then ease of manufacture improves, but manufacturing precision deteriorates due to shrinkage variation of 1-3% during firing
Solution Approach 1:
The mandrel is inserted and positioned in the green state to pre-form the threaded structure. The mandrel acts as a precision template that defines the final thread geometry. After firing, the ceramic shrinks uniformly, but the threaded structure maintains its dimensional accuracy relative to the mandrel's predefined geometry, achieving both ease of manufacture and acceptable precision.
Solution Approach 2:
The mandrel serves as an intermediary element that transfers the desired thread geometry to the ceramic body. The mandrel is inserted into the green ceramic, and its external threads imprint the internal thread form onto the ceramic. This intermediary approach allows simple tooling to create precise threads that will withstand the dimensional changes during firing.
3Reliability
If external fixtures are used to compress o-rings against module faces, then sealing reliability improves, but device complexity and footprint increase
Solution Approach 1:
The patent merges the sealing function with the structural body by integrating an o-ring groove directly into the ceramic module face. The o-ring is seated in this groove and compressed against a mating surface when modules are assembled. This eliminates the need for separate external compression fixtures, reducing device complexity and footprint while maintaining sealing reliability through the integrated design.
Solution Approach 2:
The module body itself provides the sealing function through the integrated o-ring groove, eliminating the need for external sealing fixtures. The groove geometry and positioning are built into the module during manufacturing, allowing the module to serve its own sealing needs without additional external structures, thus reducing overall device complexity.
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 method simplifies the formation of internal threads within ceramic microfluidic modules, reducing costs and complexity by enabling the direct assembly of metallic couplers without the need for external fixtures and minimizing material stress, while accommodating shrinkage and thermal expansion differences.
Implementation Method 1
firing the green-state structure and the insert together
Implementation Method 2
accommodating shrinkage and thermal expansion differences
Data Source
Figure 1~2
Figure 3~6
AI summary
A method of forming complex structures in a ceramic-, glass- or glass- ceramic-body microfluidic module is disclosed including the steps of providing at green-state refractory- material structure (140) comprising least a portion of a body of a microfluidic module, providing a removeable insert (120) formed of a carbon or of a carbonaceous material having an external surface comprising a negative surface (122) of a desired surface to be formed in the microfluidic module, machining an opening (132) in the green-state structure (140), positioning the insert (120) in the opening (132), firing the green-state structure (140) and the insert (120) together, and after firing is complete, removing the insert (120). The insert (120) is desirably a screw or screw shape, such that interior threads are formed thereby. The insert (120) desirably comprises graphite, and the structure desirably comprises ceramic, desirably silicon carbide.