Carbon Nanotube Arrays with Gradient Catalyst Thickness
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Solution Overview
Problem
Current methods for growing carbon nanotubes are limited in creating devices with diverse orientations, as they primarily align linearly or perpendicularly on substrates, making it difficult to produce complex structures with multiple orientations using external fields.
Innovation Solution
A method involving a substrate with a shadow mask layer and a sputter source to form a catalyst layer with varying thickness, where the carbon nanotubes grow fastest at specific regions, allowing for the formation of arc-shaped carbon nanotube arrays with multiple orientations through chemical vapor deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If chemical vapor deposition is used to grow carbon nanotubes with external fields (electric or magnetic field), then the nanotubes can be aligned in specific directions, but it is difficult to generate localized complicated structures with plural orientations
Solution Approach 1:
The patent applies local quality by creating catalyst layers with spatially varying thicknesses. Different regions of the substrate receive catalyst layers of different thicknesses, which directly control the orientation and growth characteristics of carbon nanotubes in each local area. This allows plural orientations to be achieved through localized catalyst properties rather than complex external field control.
Solution Approach 2:
The patent uses preliminary action by pre-forming catalyst layers with specific thickness distributions before carbon nanotube growth. The catalyst layer thickness is controlled during deposition to predetermined patterns, which pre-determine the future orientation and arrangement of carbon nanotubes. This eliminates the need for complex real-time external field control during growth.
2Adaptability or versatility
If uniform catalyst layers are used for carbon nanotube growth, then the growth process is simple, but the resulting nanotube orientations are limited to linear or perpendicular alignment
Solution Approach 1:
The patent transforms uniform catalyst layers into non-uniform catalyst layers with spatially varying thicknesses. Each local region has a catalyst thickness optimized for specific nanotube orientations, enabling diverse nanotube arrangements while maintaining precise control through the deliberate design of thickness gradients.
Solution Approach 2:
The patent changes the physical parameter of catalyst layer thickness from uniform to graded variations. By controlling the thickness parameter across different spatial locations, the patent achieves different nanotube growth orientations and densities, expanding the range of possible structures while maintaining manufacturing precision through controlled deposition parameters.
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
Enables the creation of carbon nanotube-based devices with plural orientations, leveraging the strong Van der Waals forces between nanotubes to achieve complex structures that would be challenging with existing alignment techniques.
Implementation Method 1
disposing a sputter source on the shadow mask layer, the sputter source being configured for supplying a catalyst material and depositing the catalyst material onto the substrate
Implementation Method 2
forming at least one carbon nanotube array extending from the catalyst layer using a chemical vapor deposition process
Implementation Method 3
leveraging the strong Van der Waals forces between nanotubes to achieve complex structures
Data Source
AI summary
A method for making a carbon nanotube-based device is provided. A substrate having a shadow mask layer to define an unmasked surface area thereon is provided. A sputter source is disposed on the shadow mask layer. The sputter source is configured for supplying a catalyst material and depositing the catalyst material onto the substrate. A catalyst layer including at least one catalyst block is formed on the substrate. A thickness of the at least one catalyst block is gradually decreased from one end to another opposite end thereof. The at least one catalyst block has a region with a thickness proximal or equal to an optimum thickness. A carbon source gas is introduced. At least one carbon nanotube array extending from the catalyst layer using a chemical vapor deposition process is formed. The at least one carbon nanotube array is arc-shaped, and bend in a direction of deviating from the region.