Nested Coaxial Nanostructures via Segmented ALD
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Solution Overview
Problem
There is a need for nanotubes with more complex structures, higher aspect ratios, and higher surface areas, particularly for applications in ceramics, chemical sensors, and microelectronics, where existing nanotubes do not meet the required performance standards.
Innovation Solution
The development of multiple walled nested coaxial nanostructures with extremely high aspect ratios and surface areas, achieved through atomic layer deposition (ALD) or chemical vapor deposition (CVD) techniques, using nanoporous substrates and sacrificial spacer layers to form coaxial nanostructures with varying materials such as metal oxides, including HfO2, ZrO2, and ZnO, which can be used in devices like electroosmotic pumps and chemical sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If atomic layer deposition is used with long deposition dwell times to achieve high aspect ratio nanostructures, then the aspect ratio and surface area of nanostructures are improved, but the pores of the underlying porous substrates become clogged
Solution Approach 1:
The deposition process is segmented into multiple cycles with alternating deposition and cleaning steps. Rather than continuous long-duration deposition that clogs pores, the process divides deposition into discrete segments where material is deposited in controlled layers, followed by periodic cleaning to remove accumulated material from pore openings, enabling sustained high-aspect-ratio growth without pore blockage
Solution Approach 2:
The atomic layer deposition employs periodic action through cyclic deposition sequences. Material is deposited in repeated short cycles rather than continuous deposition, allowing periodic interruption to clean pore surfaces and prevent clogging. This periodic deposition-cleaning cycle enables maintaining open pores while achieving high aspect ratios through cumulative layer buildup over many cycles
2Area of stationary object
If conventional nanotube structures are used, then the manufacturing process is simpler, but the surface area and aspect ratio are insufficient for high-performance applications
Solution Approach 1:
The invention implements nested coaxial nanotube structures where multiple nanotubes are arranged concentrically, with inner nanotubes surrounded by outer nanotubes. This nesting configuration dramatically increases the total surface area and aspect ratio compared to single-walled structures, while the modular nested architecture allows systematic fabrication through repeated deposition cycles forming each concentric layer
Solution Approach 2:
The coaxial nanotube structure functions as a composite material system with multiple materials deposited in concentric layers. Different functional materials (metals, semiconductors, insulators) are deposited in alternating layers to create multi-material composite nanotubes, where each layer contributes specific properties, achieving high surface area and aspect ratio while providing tailored functional characteristics for specific applications
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
These nanostructures exhibit superior properties and performance in devices such as electroosmotic pumps and chemical sensors, offering higher efficiency and durability due to their high aspect ratios and surface areas, surpassing conventional technologies.
Implementation Method 1
The multiple walled nested coaxial nanostructures may be formed using atomic layer deposition (ALD) or other suitable chemical vapor deposition (CVD) techniques to deposit different materials by coating the inner walls of the pores of various nanoporous substrates
Data Source
AI summary
Methods for making multiple walled nested coaxial nanostructures and devices incorporating the coaxial nanostructures are disclosed. The coaxial nanostructures include an inner nanostructure, a first outer nanotube disposed around the inner nanostructure, and a first annular channel between the inner nanostructure and the first outer nanotube. The coaxial nanostructures have extremely high aspect ratios, ranging from about 5 to about 1,200, or about 300 to about 1200.