Introduction

Nanotubes are among the most remarkable structures created through modern nanotechnology. Their defining characteristic is deceptively simple: a nanoscale sheet or lattice of atoms is formed into a cylindrical structure. At these dimensions, however, the resulting material can exhibit properties that are dramatically different from those of the same material at larger scales.

The most extensively studied nanotubes are carbon nanotubes (CNTs). A carbon nanotube can be viewed, in simplified form, as a sheet of graphene rolled into a seamless cylinder. Depending on how the carbon lattice is rolled, the nanotube can behave as a metal, semiconductor, or highly conductive nanoscale material.

Carbon nanotubes combine:

• Extremely high tensile strength
• Very low mass
• High electrical conductivity
• High thermal conductivity
• Large surface-area-to-volume ratios
• Exceptional aspect ratios
• Nanoscale dimensions
• Interesting optical and electronic properties

These characteristics have made nanotubes candidates for applications ranging from semiconductor transistors and sensors to batteries, structural composites, electromagnetic shielding, water purification, and quantum technologies.

Importantly, nanotubes are no longer simply a laboratory curiosity. Industrial adoption is occurring in composites, conductive materials, batteries, coatings, sensors, and other applications, while researchers continue to pursue much more ambitious applications in electronics and computing.

What Is a Nanotube?

A nanotube is a hollow, cylindrical nanostructure with a diameter typically measured in nanometers.

For perspective:

• 1 nanometer = 10⁻⁹ meter
• A human hair is roughly tens of thousands of nanometers wide.
• Some carbon nanotubes have diameters of only about one nanometer.
• Nanotubes can be thousands or millions of times longer than their diameter.

This extreme aspect ratio is one of their most important characteristics.

The term nanotube describes a structural geometry rather than a single material. Carbon nanotubes are the best known, but nanotubes can also be made from other materials.

Examples include:

• Carbon nanotubes
• Boron nitride nanotubes
• Molybdenum disulfide nanotubes
• Titanium dioxide nanotubes
• Other inorganic nanotubes

Carbon nanotubes remain particularly important because carbon’s bonding structure produces an unusual combination of mechanical, electrical, thermal, and chemical properties.

Carbon Nanotubes

Carbon nanotubes consist primarily of carbon atoms arranged in a hexagonal lattice.

The structure resembles graphene rolled into a cylinder.

There are two fundamental categories.

Single-Walled Carbon Nanotubes

A single-walled carbon nanotube (SWCNT) consists of one cylindrical graphene-like wall.

Typical characteristics include:

• Diameter on the order of ~1 nanometer
• Extremely high aspect ratio
• Strong dependence of electronic properties on atomic structure
• Excellent electrical properties
• Potential use in advanced semiconductor devices
• Strong optical and photonic behavior

SWCNTs are particularly interesting for electronics because their electronic characteristics depend on how the graphene lattice is wrapped around the cylinder.

Multi-Walled Carbon Nanotubes

A multi-walled carbon nanotube (MWCNT) consists of multiple concentric carbon nanotubes.

Typical advantages include:

• Greater structural robustness
• Relatively easier large-scale production
• Good electrical conductivity
• High thermal conductivity
• Excellent reinforcement capability
• Lower manufacturing cost than highly purified SWCNTs in many applications

MWCNTs are therefore particularly useful in composites, conductive additives, coatings, energy storage, and structural materials.

The Atomic Structure Determines the Properties

One of the most important concepts in nanotube technology is that geometry determines electronic behavior.

A carbon nanotube is characterized by a chirality vector, commonly expressed using two integers:

(n,m)

These integers describe how the graphene lattice is wrapped to form the nanotube.

The resulting nanotube can fall into different structural categories.

Important nanotube types

• Armchair nanotubes
• Zigzag nanotubes
• Chiral nanotubes

The chirality affects:

• Electronic band structure
• Electrical conductivity
• Bandgap
• Optical absorption
• Raman response
• Carrier transport
• Interaction with electromagnetic radiation

This means that two carbon nanotubes made from exactly the same element—carbon—can behave very differently simply because their atomic lattices are wrapped differently.

Metallic vs. Semiconducting Nanotubes

A particularly important property of carbon nanotubes is whether they behave as a metal or semiconductor.

In simplified terms, the relationship between the nanotube’s structural indices and its electronic properties determines its behavior.

A useful approximation is:

• If n − m is divisible by 3, the nanotube can exhibit metallic or near-metallic behavior.
• Other chiralities generally produce semiconducting nanotubes.

The distinction is critical for electronics.

Metallic nanotubes

Potential uses include:

• Conductive interconnects
• Transparent conductors
• Electrodes
• Conductive composites
• Current collectors

Semiconducting nanotubes

Potential uses include:

• Transistors
• Logic circuits
• Sensors
• Photodetectors
• Nanoelectronic switches

Controlling the ratio and purity of metallic versus semiconducting nanotubes remains one of the major challenges in turning CNTs into large-scale electronic systems.

Why Carbon Nanotubes Are So Strong

The strength of carbon nanotubes comes from the sp² carbon-carbon bonds forming their atomic lattice.

Individual nanotubes can exhibit exceptional tensile strength relative to their mass.

Important characteristics include:

• Very high specific strength
• High Young’s modulus
• Low density
• Strong resistance to deformation
• High stiffness along the tube axis

This makes CNTs attractive as reinforcement materials.

However, an important engineering distinction exists between the properties of an individual nanotube and those of a bulk material made from millions of nanotubes.

Individual CNTs can be extraordinarily strong, but transferring that strength efficiently into a composite requires excellent:

• Alignment
• Dispersion
• Interfacial bonding
• Load transfer
• Manufacturing consistency

This is one of the central challenges in structural CNT applications.

Electrical Properties

Carbon nanotubes can transport electrical charge extremely efficiently.

Their quasi-one-dimensional structure produces unusual electron transport behavior.

Under appropriate conditions, electrons can travel through nanotubes with relatively little scattering.

Important properties include:

• High carrier mobility
• High current-carrying capability
• Low-dimensional electronic behavior
• Potentially ballistic or quasi-ballistic transport over short distances
• Strong gate control in semiconducting CNTs

These properties make CNTs particularly attractive for transistors.

Recent research continues to address the practical gap between the excellent properties of individual nanotubes and the performance of large-scale CNT assemblies. Purity, processing, alignment, and contact resistance remain important limitations.

Thermal Properties

CNTs are also exceptional thermal conductors along their axis.

This creates opportunities for thermal-management systems.

Potential applications include:

• Heat spreaders
• Thermal interface materials
• Electronics cooling
• Battery thermal management
• Aerospace composites
• High-power electronics
• Thermal conductive polymers

CNTs can create conductive pathways through otherwise insulating materials.

This is especially useful when a polymer needs to retain its low density while gaining electrical or thermal conductivity.

Current Applications

Nanotubes are already being used or evaluated in a wide variety of commercial and industrial applications.

1. Composite Materials

One of the most mature CNT applications is reinforcement of polymers and other materials.

CNTs can provide:

• Increased mechanical strength
• Increased stiffness
• Improved electrical conductivity
• Improved thermal conductivity
• Reduced electrostatic buildup
• Electromagnetic interference shielding

CNT-polymer composites are being investigated and deployed across structural, electrical, energy, and sensing applications. Recent work emphasizes improved dispersion, functionalization, scalable processing, and interfacial engineering.

2. Batteries

CNTs are increasingly important in energy storage.

Rather than necessarily being the primary active battery material, CNTs can create a conductive network through an electrode.

This can improve electrical transport while also providing mechanical support.

Current and emerging applications include:

• Lithium-ion batteries
• Silicon anodes
• High-loading electrodes
• Conductive additives
• Freestanding electrodes
• Current collectors
• Dry-electrode manufacturing
• Next-generation battery architectures

Recent reviews identify conductive networks, current collectors, freestanding electrodes, and CNT-containing anodes as major areas of research.

3. Sensors

The enormous surface-to-volume ratio of nanotubes makes them highly sensitive to their environment.

When molecules interact with the nanotube surface, they can alter its:

• Electrical conductivity
• Carrier concentration
• Local electrostatic potential
• Optical characteristics

This can produce extremely sensitive chemical or biological sensors.

Potential targets include:

• Gases
• Volatile organic compounds
• Biomolecules
• Proteins
• DNA
• Heavy metals
• Environmental pollutants

CNT-based fibers are also being investigated as sensing elements for structural composites, where mechanical deformation can change their electrical properties.

4. Water Purification

Functionalized CNTs can interact strongly with contaminants.

Their nanoscale channels and large surface areas create opportunities for advanced filtration and adsorption.

Potential targets include:

• Heavy metals
• Organic pollutants
• Dyes
• Pharmaceuticals
• Microorganisms

CNT-modified membranes can potentially improve permeability, selectivity, mechanical strength, and antifouling behavior. Research continues to investigate functionalization and scalable membrane architectures.

5. Electromagnetic Interference Shielding

Modern electronics produce increasing amounts of electromagnetic interference.

CNT composites can create electrically conductive networks capable of absorbing or reflecting electromagnetic radiation.

Potential applications include:

• Smartphones
• Aerospace electronics
• Automotive electronics
• Military electronics
• Data centers
• High-frequency electronics
• Electronic packaging

The advantage is that CNTs can provide conductivity without requiring the large mass associated with conventional metal shielding.

6. Conductive Coatings

CNTs can be incorporated into coatings to provide controlled electrical conductivity.

Applications include:

• Antistatic coatings
• Electrostatic discharge protection
• Conductive paints
• Heating elements
• Flexible electronics
• EMI shielding
• Sensors

Because CNT networks can remain conductive at relatively low loading levels, they are attractive for polymer-based coatings.

7. Aerospace and Automotive Materials

The combination of low mass, strength, electrical conductivity, and thermal conductivity makes CNT composites particularly attractive for transportation.

Potential uses include:

• Lightweight structural components
• Conductive aircraft structures
• Lightning protection
• Heated surfaces
• Battery components
• Electromagnetic shielding
• Structural health monitoring

The major challenge is translating nanoscale material performance into predictable, large-scale manufactured components.

Nanotube Electronics

The most ambitious CNT application is perhaps electronics.

Conventional silicon transistors face increasing difficulty as dimensions approach the atomic scale.

Carbon nanotubes offer a naturally nanoscale channel.

A CNT transistor can essentially use a semiconductor nanotube as the channel through which charge carriers travel.

Carbon Nanotube Field-Effect Transistors

A CNTFET typically consists of:

• Semiconducting CNT channel
• Source electrode
• Drain electrode
• Gate electrode
• Gate dielectric

The gate controls the carrier concentration in the nanotube.

Because the CNT is so small, the gate can exert strong electrostatic control over the channel.

This makes CNTFETs candidates for extremely scaled electronics.

Recent research continues to demonstrate the potential of CNT transistors for high-performance and high-frequency electronics.

A Major Recent Advance: Terahertz CNT Electronics

One of the most significant recent developments has been the demonstration of CNT-based transistor technology operating at frequencies beyond 1 THz.

Researchers have reported aligned CNT-film MOS transistors with:

• Gate length: approximately 80 nm
• Carrier mobility: > 3,000 cm²/V·s
• On-state current: approximately 3.02 mA/µm
• Peak transconductance: approximately 1.71 mS/µm
• Saturation velocity: approximately 3.5 × 10⁷ cm/s
• Cut-off frequency: greater than 1 THz

These results are important because they move CNT electronics beyond simply demonstrating nanoscale transistors and toward practical high-frequency device engineering.

Potential applications include:

• 6G communications
• Terahertz imaging
• Radar
• High-speed wireless systems
• Scientific instrumentation
• High-frequency analog electronics

Flexible CNT Electronics

CNTs are particularly attractive for flexible electronics because nanotube networks can retain electrical functionality while being mechanically flexible.

Researchers are investigating CNT electronics for:

• Flexible displays
• Wearable sensors
• Flexible RF electronics
• Electronic skins
• Medical devices
• Robotics
• Flexible antennas

In 2026, researchers reported flexible CNT radio-frequency transistors operating above 100 GHz, demonstrating that CNT electronics can combine high-frequency operation with mechanical flexibility.

Technical Section: CNT Electronic Transport

At the microscopic level, charge transport in a carbon nanotube is governed by its one-dimensional electronic structure.

The graphene band structure is modified by imposing periodic boundary conditions around the nanotube circumference.

This quantizes the allowed electronic states.

Key concepts

• Graphene has a two-dimensional band structure.
• Rolling graphene into a nanotube imposes circumferential boundary conditions.
• Allowed wave vectors become quantized.
• The resulting band structure determines whether the CNT is metallic or semiconducting.
• Carrier transport occurs primarily along the nanotube axis.
• Scattering mechanisms determine practical mobility and conductance.

For short, high-quality CNT channels, transport can approach the ballistic regime.

This is one reason CNTs remain attractive for extremely small transistor architectures.

Technical Section: CNTFET Operation

A CNTFET can be understood as a nanoscale field-effect transistor in which the CNT acts as the channel.

Basic operating sequence

• A voltage is applied between source and drain.
• The gate voltage changes the electrostatic potential around the CNT.
• Carrier concentration in the CNT changes.
• Channel conductance changes.
• The resulting current represents the transistor’s electrical state.

Critical engineering parameters

• CNT diameter
• CNT chirality
• Bandgap
• Gate length
• Gate dielectric thickness
• Dielectric constant
• Contact resistance
• Schottky-barrier formation
• CNT alignment
• CNT purity
• Defect density
• Interface trap density
• Contact geometry

The gate dielectric is particularly important because imperfect interfaces can degrade gate control and increase leakage.

Recent research has demonstrated methods for reducing interface-related limitations and improving CNT transistor performance.

Technical Section: Why CNTs Are Attractive for Scaling

A conventional transistor is a three-dimensional structure.

A CNT is essentially a one-dimensional conduction channel.

This geometry provides a potentially powerful scaling advantage.

Potential benefits

• Extremely small channel diameter
• Strong electrostatic gate control
• High carrier mobility
• High current density
• Potentially low operating voltage
• Short transport distances
• Excellent mechanical stability

Gate-all-around architectures are particularly attractive because the gate can surround the nanotube channel.

Recent work has investigated gate-all-around CNTFETs using high-k dielectrics for aggressive sub-10-nm scaling.

Technical Section: The Contact Problem

One of the major obstacles to CNT electronics is not necessarily the nanotube itself.

It is the interface between the nanotube and the metal electrodes.

The metal-CNT interface can produce:

• Contact resistance
• Schottky barriers
• Fermi-level pinning
• Carrier injection limitations
• Device-to-device variability

As transistor dimensions shrink, contact resistance becomes increasingly important because the contact can represent a substantial fraction of the total device resistance.

Consequently, future CNT electronics will require advances in:

• Contact metallurgy
• Interface engineering
• Doping
• Contact geometry
• Surface treatment
• Semiconductor processing

Technical Section: CNT Purification and Sorting

A practical CNT transistor technology needs very precise control over nanotube populations.

A manufactured CNT mixture may contain:

• Metallic CNTs
• Semiconducting CNTs
• Different diameters
• Different chiralities
• Different lengths
• Structural defects
• Catalyst residues
• Amorphous carbon

For digital logic, unwanted metallic CNTs can create leakage paths or short circuits.

Therefore, advanced CNT electronics requires methods for:

• Chirality sorting
• Metallic/semiconducting separation
• Diameter control
• Length control
• Defect reduction
• High-purity synthesis
• Precise placement

This is one reason the transition from an individual laboratory transistor to billions of interconnected transistors remains challenging.

Technical Section: CNT Manufacturing

Several major synthesis methods are used.

Chemical Vapor Deposition

CVD is one of the most important approaches.

Typical process elements include:

• Carbon-containing precursor gas
• Catalyst nanoparticles
• Elevated temperature
• Controlled atmosphere
• Substrate growth

Advantages include:

• Scalability
• Direct growth on substrates
• Potential alignment
• Compatibility with device fabrication

Arc Discharge

An electric arc between carbon electrodes can generate CNTs.

Advantages:

• High-quality nanotubes

Disadvantages:

• More difficult purification
• Less convenient control of nanotube structure

Laser Ablation

A high-energy laser vaporizes carbon material from a target.

Advantages:

• High-quality CNT production

Disadvantages:

• Higher equipment complexity
• Energy-intensive processing

Technical Section: Functionalization

CNT surfaces can be chemically modified to change their properties.

Two broad strategies are commonly used.

Covalent functionalization

Chemical groups are bonded directly to the nanotube.

Advantages:

• Strong chemical attachment
• Controlled chemical functionality

Disadvantages:

• Can disrupt the carbon lattice
• May reduce electrical conductivity

Non-covalent functionalization

Molecules interact with the nanotube without permanently altering its carbon lattice.

Advantages:

• Preserves the nanotube’s electronic structure more effectively
• Can improve dispersion

Disadvantages:

• Potentially weaker attachment

Functionalization is particularly important for:

• Biosensors
• Water purification
• Composite materials
• Drug delivery research
• Chemical sensors
• Selective separation

Technical Section: CNT Networks

A single CNT can have extraordinary properties, but many commercial products use networks of nanotubes.

A CNT network forms a percolating conductive structure.

At sufficiently high nanotube concentration, individual CNTs begin connecting to form continuous electrical pathways.

This is known as percolation.

Important parameters

• CNT concentration
• Aspect ratio
• Orientation
• Dispersion
• Tube-to-tube contact resistance
• Network morphology
• Functionalization
• Processing method

The percolation threshold can be very low because CNTs have extremely high aspect ratios.

This allows a small quantity of CNTs to convert an insulating polymer into a conductive composite.

Technical Section: CNTs in Energy Storage

CNTs are increasingly important as conductive and structural components in batteries.

A CNT network can provide an electrically conductive skeleton throughout an electrode.

Potential functions

• Electron transport
• Mechanical reinforcement
• Current collection
• Structural support
• Improved electrode integrity
• Reduced electrical resistance

This is especially interesting for silicon-based anodes.

Silicon can store large amounts of lithium but experiences substantial volume changes during cycling.

CNT networks can potentially provide a flexible conductive framework that helps accommodate these mechanical changes.

Current research is investigating CNT-based electrodes, conductive networks, current collectors, and dry-electrode architectures.

Technical Section: CNTs as Molecular-Scale Channels

The hollow interior of a nanotube creates another unusual possibility.

CNTs can act as nanoscale channels for:

• Molecules
• Water
• Ions
• Gases

Under the right conditions, transport through nanotube channels can differ dramatically from transport through conventional pores.

This has generated significant interest in:

• Desalination
• Water purification
• Molecular filtration
• Chemical separation
• Nanofluidics

Functionalized CNT membranes are an active research area because researchers can potentially tune the chemical interaction between the nanotube and the molecules passing through it.

Future Applications

The future of nanotubes extends well beyond today’s commercial uses.

1. Next-Generation Semiconductor Processors

CNT transistors could eventually complement or replace silicon transistors in specialized applications.

Potential advantages include:

• Sub-10-nm transistor architectures
• High switching speed
• High current density
• Low-voltage operation
• High-frequency operation
• Flexible electronics

The greatest opportunity may not be replacing every silicon transistor but integrating CNT devices where their unique characteristics provide a compelling advantage.

2. Terahertz Communications

The recent demonstration of CNT transistors above 1 THz makes high-frequency communications one of the most interesting long-term opportunities.

Potential applications include:

• 6G wireless communications
• Terahertz backhaul
• High-resolution radar
• Imaging
• Security screening
• Atmospheric sensing
• Spectroscopy

3. AI Hardware

CNTs could potentially play a role in future AI processors.

Possible architectures include:

• CNT transistor logic
• Analog AI circuits
• Neuromorphic processors
• In-memory computing
• Sensor-processing systems
• Ultra-low-power edge AI

Their high-frequency operation and nanoscale dimensions make CNTs particularly interesting for specialized hardware.

4. Quantum Technologies

CNTs are also entering the quantum-device arena.

Carbon nanotubes can form quantum dots and can host highly controllable electronic states.

Researchers have demonstrated carbon-nanotube-based superconducting qubit structures, including gatemon-type qubits.

Potential applications include:

• Quantum computing
• Quantum sensing
• Quantum communication
• Hybrid quantum systems

This remains an emerging research field rather than a mature commercial application.

5. Structural Health Monitoring

CNT composites can potentially turn structural materials into sensors.

If a CNT network is embedded in a composite, mechanical deformation can alter the network’s electrical resistance.

The material can therefore potentially report:

• Strain
• Cracks
• Impact damage
• Fatigue
• Delamination
• Structural deformation

This could lead to aircraft wings, bridges, vehicles, and other structures that continuously monitor their own physical condition.

6. Advanced Energy Systems

Future CNT applications could extend across the energy sector.

Potential areas include:

• Lithium-ion batteries
• Solid-state batteries
• Supercapacitors
• Fuel cells
• Solar cells
• Hydrogen systems
• Thermal management
• Conductive electrodes

CNTs may be particularly valuable as an enabling material rather than the primary energy-storage material.

7. Artificial Muscles and Actuators

CNT yarns and fibers can exhibit interesting electromechanical behavior.

Potential applications include:

• Robotics
• Artificial muscles
• Prosthetics
• Wearable devices
• Soft robotics
• Aerospace actuators

CNT fibers combine low mass with electrical conductivity and mechanical flexibility, creating opportunities that conventional metal wires cannot easily provide.

The Biggest Remaining Challenges

The extraordinary properties of individual nanotubes should not obscure the engineering difficulties involved in producing useful systems.

Major challenges include:

• Controlling nanotube chirality
• Eliminating metallic CNTs from semiconductor applications
• Producing highly uniform nanotubes
• Reducing defects
• Controlling diameter
• Aligning nanotubes
• Improving dispersion
• Reducing tube-to-tube contact resistance
• Improving CNT-metal contacts
• Reducing manufacturing costs
• Developing high-throughput fabrication
• Ensuring reproducibility
• Integrating CNTs with conventional semiconductor manufacturing
• Addressing environmental and occupational safety concerns

These issues explain why CNT technology has progressed rapidly in some applications while remaining primarily developmental in others.

The Most Important Trend: From Individual Nanotubes to Engineered Systems

The field is gradually moving through several stages.

Stage 1 — Discover the material

Researchers established that CNTs possess exceptional:

• Strength
• Conductivity
• Thermal transport
• Optical behavior

Stage 2 — Demonstrate individual devices

Researchers created:

• CNT transistors
• Sensors
• Nanoelectronic devices
• Experimental energy-storage structures

Stage 3 — Control manufacturing

The focus shifted toward:

• Purification
• Sorting
• Alignment
• Functionalization
• Large-scale synthesis

Stage 4 — Build CNT networks

Researchers began engineering:

• CNT films
• Fibers
• Composites
• Conductive networks
• Membranes

Stage 5 — Integrate nanotubes into systems

The emerging challenge is now system-level integration:

• Semiconductor manufacturing
• Battery manufacturing
• Aerospace composites
• Flexible electronics
• Sensors
• AI hardware
• High-frequency communications

This transition from material science to systems engineering is arguably the most important development in the field.

Outlook

Carbon nanotubes have existed as a major research topic for more than three decades, yet the technology continues to evolve.

The early vision was that nanotubes might simply become “the next material after silicon.” The reality is more nuanced.

CNTs are likely to become important in several different technological roles simultaneously.

They can function as:

• Structural reinforcement
• Electrical conductors
• Semiconductor channels
• Thermal conductors
• Sensors
• Battery additives
• Membrane materials
• Electromagnetic absorbers
• Quantum-device components
• Nanoscale fluidic channels

The strongest near-term opportunities appear to be in composites, energy storage, conductive materials, sensing, and specialized electronics, where CNTs can provide benefits without requiring the entire manufacturing ecosystem to be redesigned.

The longer-term opportunity is much larger.

If researchers solve the remaining problems of purification, chirality control, alignment, contacts, large-scale integration, and cost, CNTs could become important components of sub-10-nanometer electronics, terahertz communications, AI hardware, flexible electronics, quantum devices, and advanced energy systems.

The recent demonstration of CNT transistors with cut-off frequencies above 1 THz illustrates how far the technology has progressed.

The fundamental advantage of nanotubes is that they combine atomic-scale dimensions with exceptional physical properties. The fundamental challenge is converting those properties into reliable, inexpensive, manufacturable systems.

That engineering problem—not the discovery of new properties—is likely to determine how important nanotubes ultimately become.

Conclusion

Nanotubes represent one of the most versatile platforms in nanotechnology.

Their significance comes from the unusual combination of:

• Atomic-scale dimensions
• High mechanical strength
• Exceptional electrical transport
• High thermal conductivity
• Large surface area
• Unique quantum and electronic behavior

Today, nanotubes are already finding practical roles in composites, batteries, coatings, sensors, electromagnetic shielding, and other technologies.

At the leading edge of research, however, CNTs are being pushed toward a very different class of applications: high-frequency electronics, advanced transistors, AI hardware, quantum computing, nanoscale filtration, and intelligent structural materials.

The future of nanotubes will therefore not be defined by a single breakthrough. It will depend on the continued convergence of materials science, semiconductor engineering, chemistry, manufacturing, and device physics.

If that convergence succeeds, nanotubes could become one of the important enabling technologies of the post-silicon era.