Covalent Functionalization of Surface-Grown Carbon Nanotubes

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Solution Overview

Problem

Existing methods for functionalizing carbon nanotubes (CNTs) grown on a surface are inefficient and prone to errors, as they require harsh chemicals that can damage underlying metal films and are not CMOS compatible, leading to reproducibility issues and potential short-circuiting.

Innovation Solution

A method for directly covalently functionalizing CNTs on a surface using a chemical attachment with a linker and functional groups, which can change hydrophobicity or attach catalysts or biomolecules, employing cycloaddition, amide coupling, and CuAAC steps without the need for electrical connections, allowing for mild conditions and CMOS compatibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional functionalization methods using harsh oxidizing agents are employed, then CNTs can be functionalized to enhance solubility, but the underlying metal films are attacked and damaged

Engineering Contradiction:

Improvefunctionalization effectivenessVSAvoiddamage to metal films

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention changes the chemical parameters of the functionalization process by using mild reagents (amines, aldehydes, ketones) instead of harsh oxidizing agents, enabling functionalization without damaging the metal films while maintaining CNT structural integrity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention introduces intermediary functional groups (such as carboxyl, amine, or hydroxyl groups) that serve as attachment points for biomolecules, allowing indirect functionalization that protects the metal films from direct exposure to harsh chemicals

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If dispersive functionalization technique is used, then CNTs can be functionalized in solution, but larger process errors and reproducibility issues occur

Engineering Contradiction:

Improvefunctionalization processabilityVSAvoiddevice reproducibility

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The invention performs preliminary action by pre-growing CNT forests on chip with controlled morphology and electrical properties, then applying functionalization in situ, which ensures consistent starting conditions and reduces variability in final device performance

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention extracts the functionalization step from the solution-based process and applies it directly in situ on-chip, eliminating the dispersion and redeposition steps that introduce process errors and improve reproducibility

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If electrochemical functionalization is employed, then CNTs can be functionalized with electrical connections, but risk of short circuiting increases

Engineering Contradiction:

Improveelectrical connectivityVSAvoidshort circuiting risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention introduces electrical insulation as an intermediary layer or property during functionalization, allowing electrical connections to be maintained while preventing direct conductive paths that would cause short circuits between adjacent CNTs or electrodes

Inventive Principle:

Principle #24Intermediary (Mediator)

4Reliability

If harsh chemicals are used for functionalization, then CNTs can be modified, but CMOS compatibility is lost

Engineering Contradiction:

Improvefunctionalization effectivenessVSAvoidCMOS compatibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The invention changes the chemical parameters of the functionalization process to use mild, CMOS-compatible reagents and conditions (ambient or moderate temperatures, aqueous or organic solvents without aggressive chemicals), enabling integration with standard CMOS fabrication processes

Inventive Principle:

Principle #35Parameter changes

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 enables reliable and reproducible functionalization of CNTs on-chip, preserving electrical properties and morphology, and allows for the attachment of biomolecules, enhancing their use in biosensors and other applications without damaging the underlying metal films.

Implementation Method 1

employing cycloaddition, amide coupling, and CuAAC steps

Methodology Applied

Scientific EffectCycloaddition:

Implementation Method 2

employing cycloaddition, amide coupling, and CuAAC steps

Methodology Applied

Scientific EffectAmide coupling:

Implementation Method 3

employing cycloaddition, amide coupling, and CuAAC steps

Methodology Applied

Scientific EffectCopper(I)-catalyzed azide alkyne cycloaddition (CuAAC):

Implementation Method 4

The first chemical modification to the CNT nanostructures can change the hydrophobicity of the structures (i.e. making them hydrophobic or hydrophilic)

Methodology Applied

Scientific EffectHydrophobicity modification: Hydrophobe

Data Source

PatentEP2823094B1Covalent functionalization of carbon nanotubes grown on a surface

Publication Date: 2021.10.06 KHALID WAQAS

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AI summary

The present invention is related to a new method for directly covalently functionalizing carbon nanotubes (CNTs) grown on or attached to a surface. The invention also features devices that are comprised of CNTs.