Carbon Nanotube Array Separation via Bottom-End Oxidation
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Solution Overview
Problem
Carbon nanotube arrays grown on substrates via CVD methods face challenges in separation due to strong bonding forces, making it difficult to peel them off without damaging the arrays.
Innovation Solution
A device comprising a chamber, gas transporting pipe, and gas diffusing unit is used to grow carbon nanotubes, where the bottom ends are oxidized to weaken the bonding force, allowing for easy separation by applying external forces like tilting or blowing, while maintaining the integrity of the array.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon nanotube arrays are grown on a growth substrate by CVD method, then the carbon nanotube arrays can be successfully grown with good quality, but the bonding force between the carbon nanotubes and the growth substrate becomes too strong making separation difficult
Solution Approach 1:
The patent applies preliminary action by introducing an oxidizing atmosphere during the carbon nanotube growth process to pre-oxidize the bottom ends of the carbon nanotubes. This preliminary oxidation weakens the bonding between the nanotubes and substrate before separation is attempted, making subsequent peeling operations feasible while maintaining array integrity
Solution Approach 2:
The patent changes the chemical state parameter of the carbon nanotube bottom ends by exposing them to oxygen-containing atmosphere. This parameter change (oxidation) modifies the bonding characteristics at the interface between nanotubes and substrate, reducing adhesion strength and enabling easy separation while preserving the structural integrity of the nanotube arrays
2Ease of operation
If the carbon nanotube array is peeled from the growth substrate using a knife or tweezer, then separation can be attempted, but the strong bonding force makes it difficult to obtain an integrated carbon nanotube array
Solution Approach 1:
The oxidization treatment is performed as a preliminary action before mechanical separation. By pre-oxidizing the carbon nanotube bottom ends during or after growth, the bonding interface is weakened in advance, allowing subsequent manual or mechanical peeling to proceed easily without damaging the nanotube array structure
Solution Approach 2:
The chemical parameter of the nanotube-substrate interface is changed through oxidation, transforming the strong chemical bonding into a weaker oxidized state. This parameter change enables easy mechanical separation while maintaining the integrity of the carbon nanotube arrays, solving the contradiction between ease of separation and manufacturing precision
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 successful separation of carbon nanotube arrays from the substrate without damaging them, resulting in a free-standing, high-quality, and integrated structure.
Implementation Method 1
supplying an oxygen containing gas to the gas transporting pipe (14) from the first end (142), and heating the carbon nanotube array to a second temperature, to oxidize the bottom end of each of the plurality of carbon nanotubes
Implementation Method 2
heating the growth substrate (13) to a first temperature, to grow the carbon nanotube array on the first growth substrate surface (132)
Implementation Method 3
heating the carbon nanotube array to a second temperature, to oxidize the bottom end of each of the plurality of carbon nanotubes
Implementation Method 4
supplying a carbon source gas and the protective gas to the chamber (12) from the first inlet (1222), and heating the growth substrate (13) to a first temperature, to grow the carbon nanotube array on the first growth substrate surface (132)
Data Source
AI summary
A method for making a carbon nanotube array includes placing a gas diffusing unit defining an outlet in a chamber including a first inlet and a second inlet. A gas transporting pipe haves a first end and a second end opposite to the first end, the second end is connected to the gas diffusing unit, and the first end passes through the second inlet and extends out of the chamber. A growth substrate defining a through hole covers the outlet. A carbon source gas and a protective gas is supplied to the chamber from the first inlet, to grow a carbon nanotube array including multiple carbon nanotubes. Each carbon nanotube has a bottom end. Then the carbon source gas is stopped supplying, and an oxygen containing gas is supplied to the gas transporting pipe, to oxidize the bottom end.