Microscale Metallic CNT Templated Devices
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Solution Overview
Problem
Current precision manufacturing of three-dimensional microscale structures is limited to low aspect ratios and a narrow range of materials, particularly for metals and metal alloys, which hinders the development of high sensitivity and stability in microelectromechanical systems (MEMS) such as gyros used in navigation and sensing applications.
Innovation Solution
The development of a microscale device featuring a patterned forest of vertically grown and aligned carbon nanotubes with a conformal coating and metallic interstitial material, where the metallic interstitial material is infiltrated using an electroplating process, allowing for the creation of high aspect ratio structures with a thickness of at least three microns and aspect ratios greater than 100:1, enabling robust and sensitive MEMS devices like gyros.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional precision manufacturing methods are used for microscale structures, then manufacturing simplicity is maintained, but aspect ratio is limited to low values and material selection is restricted
Solution Approach 1:
The patent uses carbon nanotube forests as an intermediary template structure. These forests are grown vertically to achieve high aspect ratios (greater than 100:1), then serve as molds for electroplating metallic interstitial material. This intermediary approach enables fabrication of high aspect ratio metal structures that would be impossible with conventional direct manufacturing methods.
Solution Approach 2:
The patent changes the manufacturing approach from direct metal fabrication to a two-step process: first growing carbon nanotube forests with controlled height and density parameters, then electroplating metal into the interstices. This parameter transformation allows achieving aspect ratios greater than 100:1 and enables metal materials that were previously inaccessible at microscale.
2Strength
If metals and metal alloys are used at microscale, then mechanical strength and stability are improved, but manufacturing barriers prevent high aspect ratio structure formation
Solution Approach 1:
The patent performs preliminary action by growing carbon nanotube forests with high aspect ratios before introducing the metal material. The nanotube forests are pre-formed with controlled height, density, and alignment, creating a template that guides subsequent metal electroplating. This preliminary structuring enables the final metal structure to inherit the high aspect ratio geometry.
Solution Approach 2:
The patent creates a composite structure consisting of carbon nanotube forests with infiltrated metallic interstitial material. The carbon nanotubes provide the high aspect ratio framework, while the metal material fills the interstices to provide mechanical strength and stability. This composite approach combines the advantages of both materials.
3Strength
If conformal coating is applied to carbon nanotube forests, then structural robustness is improved, but interstice filling may be compromised
Solution Approach 1:
The patent applies conformal coating to the carbon nanotube surfaces, but intentionally leaves the interstices partially unfilled. The coating provides sufficient structural robustness for liquid processing while maintaining open interstices that allow metallic material to infiltrate during electroplating. This partial filling approach balances structural integrity with material infiltration.
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 enables the fabrication of high aspect ratio, three-dimensional microscale structures from metals and metal alloys, enhancing the sensitivity and stability of MEMS devices like gyros, achieving higher capacitance sensitivity and reduced drift performance, while being cost-effective and minimizing distortion and stress.
Implementation Method 1
The metallic interstitial material may be applied by an electroplating process
Data Source
AI summary
A method for forming a microscale device may include growing, by a chemical vapor deposition, a patterned forest of vertically aligned carbon nanotubes, wherein the patterned forest defines a component of the microscale device, and applying a conformal non-metal coating to the vertically aligned carbon nanotubes throughout the patterned forest, wherein the conformal non-metal coating comprises a substantially uniform thickness along a length of the vertically aligned carbon nanotubes. The method may also include connecting adjacent vertically aligned carbon nanotubes together with the conformal non-metal coating without filling interstices between the adjacent vertically aligned carbon nanotubes, wherein the connecting of the vertically aligned carbon nanotubes is configured to increase a strength of the vertically aligned carbon nanotubes of the patterned forest above a threshold level to withstand forces applied during a wet etching process, and infiltrating the interstices between the adjacent vertically aligned carbon nanotubes with a metallic material.