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Nanotechnology enables designing and creating structures and devices utilising extraordinary properties and behaviour of matter at very fine length scales – nanoscale level (10-9 m). Between 2001 and 2004, approximately 60 countries globally implemented national nanotechnology programmes. According to R.D Shelton, an international technology assessor, research and development in this area “has now become a socio-economic target…an area of intense international collaboration and competition.” As of 2017, data showed 4725 patents published in USPTO by the USA alone, maintaining their position as a leader in nanotechnology for over 20 years.
It is one of the major areas of research that is revilutionising the future defence and security. A wide array of technologies including new engineered materials, advanced miniaturized sensors, secure communication networks, micro-scale robot and efficient power sources etc will become possible using nanotechnology.
It will lead to drastic improvements in many military technologies including high performance platforms, enhanced sensing, safer operation in hazardous circumstances through remotely operated robots and so on. These advances are expected to markedly change the military capabilities and possibly even shape the future warfare as the field moves to a much higher level of maturity in the next few decades.
Carbon nanotubes (CNTs) are hollow cylindrical tubes formed by rolling a sheet of carbon atoms arranged in a hexagonal ring, as in a sheet of graphite, either in monolayer (single walled nanotube, SWCNT) or multilayer (multi-walled nanotube, MWCNT) form. Their diameter may range from 0.7 (SWCNT) to 50 naometers (MWCNT) and few tens of micron in length.
CNT being a hollow tube comprised entirely of carbon, they are also extremely light weight. They exhibit extraordinary strength and unique electrical properties, at the individual tube level: 200X the strength and 5X the elasticity of steel; 5X the electrical conductivity, 15X the thermal conductivity and 1,000X the current capacity of copper; at almost half the density of aluminum.
The unique physical, electrical, and molecular properties of carbon nanotubes (CNTs) cause them to be the focus of research for a wide range of applications. Due to their high strength and elastic modulus, CNTs are being finding application as reinforcements in composites like polymer matrix composites (PMCs). CNT fibre and thread are being envisaged for applications as reinforcements in composites or woven for bullet proof vests and high strength ropes.
They also provide large specific surface area making it a potential material for sensing applications. It can be made highly selective for a range of gases / vapours by modifying the CNT surface by functionalisation (attaching group of atoms or molecules on the graphitic structure). Their hollow structure also acts as a storage space for hydrogen, drug etc required for certain applications like energy storage and targeted drug delivery.
UC professor Vesselin Shanov co-directs UC’s Nanoworld Laboratories with research partner and UC professor Mark Schulz. Together, they harness their expertise in electrical, chemical and mechanical engineering to craft “smart” materials that can power electronics. “The major challenge is translating these beautiful properties to take advantage of their strength, conductivity and heat resistance,” Shanov said.
Defense industry is also investing heavily in CNT research initiatives and manufacturers. And the technology is already finding its way into several military applications. Some of the Successful transitions of nanotechnology into defence products have been increasing the Lifetime of material coatings increased from hours to years, through
Nano-structured silicate manipulation reducing insulation weight by 980 lbs, and High Power Microwave (HPM) devices with reduced weight, shape and power consumption
UC’s College of Engineering and Applied Science has a five-year agreement with the Air Force Research Laboratory to conduct research that can enhance military technology applications. Schulz said manufacturing is at the cusp of a carbon renaissance. Carbon nanotubes will replace copper wire in cars and planes to reduce weight and improve fuel efficiency. Carbon will filter our water and tell us more about our lives and bodies through new biometric sensors. Carbon will replace polyester and other synthetic fibers. And since carbon nanotubes are the blackest objects found on Earth, absorbing 99.9 percent of all visible light, you might say carbon is the new black. “In the past, metals dominated manufacturing goods,” Schulz said. “But I think carbon is going to replace metals in a lot of applications. “There’s going to be a new carbon era — a carbon revolution,” Schulz said.
China also secures second place behind the United States in the amount of research publications they have released in naomaterials. In 2018, Tsinghua University, Beijing, released their findings where they have enhanced carbon nanotubes to now withstand the wight of over 800 tonnes, requiring just 1 cm^{3} of material. The scientific nanotechnology team hinted at aerospace, and armour boosting applications, showing promise for defence related nano-weapons. The Chinese Academy of Science’s Vice President Chunli Bai, has stated the need to focus on closing the gap between “basic research and application,” in order for China to advance its global competitiveness in nanotechnology.
Defence and Security Applications
Most recent research into military nanotechnological weapons includes production of defensive military apparatus, with objectives of enhancing existing designs of lightweight, flexible and durable materials. These innovative designs are equipped with features to also enhance offensive strategy through sensing devices and manipulation of electromechanical properties.
They can replace copper wire and cable because it’s much lighter weight. They present an alternative to optical fiber, as they provide similar weight savings while utilizing the same electron based connector systems that engineers are using today. They also have good electron emission characteristics. These properties enable them for applications in shielding against electrostatic charges and EMI pulses.
Army project may improve military communications by boosting 5G technology
An Army-funded project may boost 5G and mm-Wave technologies, improving military communications and sensing equipment.
Carbonics, Inc., partnered with the University of Southern California to develop a carbon nanotube technology that, for the first time, achieved speeds exceeding 100GHz in radio frequency applications. The milestone eclipses the performance — and efficiency — of traditional Radio Frequency Complementary Metal-Oxide Semiconductor, known as RF-CMOS technology, that is ubiquitous in modern consumer electronics, including cell phones.
“This milestone shows that carbon nanotubes, long thought to be a promising communications chip technology, can deliver,” said Dr. Joe Qiu, program manager, solid state and electromagnetics at the Army Research Office. “The next step is scaling this technology, proving that it can work in high-volume manufacturing. Ultimately, this technology could help the Army meet its needs in communications, radar, electronic warfare and other sensing applications.” The research was published in the journal Nature Electronics.
For nearly two decades, researchers have theorized that carbon nanotubes would be well suited as a high-frequency transistor technology due to its unique one-dimensional electron transport characteristics. The engineering challenge has been to assemble the high-purity semiconducting nanotubes into densely aligned arrays and create a working device out of the nanomaterial.
Carbonics, a venture backed start-up, and USC, successfully overcame this challenge. Projections based on scaling single carbon nanotube device metrics suggest the technology could ultimately far exceed the top-tier incumbent RF technology, Gallium Arsenide.
Carbonics employs a deposition technology called ZEBRA that enables carbon nanotubes to be densely aligned and deposited onto a variety of chip substrates including silicon, silicon-on-insulator, quartz and flexible materials. This allows the technology to be directly integrated with traditional CMOS digital logic circuits, overcoming the typical problem of heterogeneous integration.
“With this exciting accomplishment, the timing is ripe to leverage our CMOS-compatible technology for the 5G and mm-Wave defense communication markets,” said Carbonics’ CEO Kos Galatsis. “We are now engaged in licensing and technology transfer partnerships with industry participants, while we continue to advance this disruptive RF technology.”
ARMOR
A likely use of CNTs for the military market will be lightweight body armor. SWCNTs exhibit an extremely high elastic modulus and a high strain at tensile failure. These properties give them an excellent energy absorption capacity 10 times greater than the fiber materials normally used in soft body armor, therefore, have great potential applications in making antiballistic materials.
A team of University of Maryland students students modified ballistic grade Kevlar 29 by embedding a network of crosslinked, functionalized carbon nanotubes (CNTs), thereby doubling the ballistic resistance of the original product.
In fact, the product made by NanoRidge/RSI was chosen by the Defense Advanced Research Projects Agency (DARPA) to undergo testing and evaluation. Yet another company, Nanocomp, has been working with the U.S. Army to develop similar armor using Nanocomp’s exclusive processes. With the use of CNT fibers, along with other materials such a Kevlar, thinner and lighter body armor can provide protection from level IIIA threats and blunt trauma, and it can be used in conjunction with hard armor.
The aforementioned hard armor is typically manufactured from a ceramic such as silicon carbide or alumina. Although ceramics are quite hard, they are also brittle. Experimentation has shown that by adding just 4% (by volume) of CNT fibers to alumina, the fracturing toughness can be increased by up to 94%. Composites of liquid crystal polymers with CNTs could also be cast or molded into armor plates and helmets.
Clearly, CNTs have multiple applications in armor and are seen as a vital technology that can improve the ability of armor to sustain ballistic energies, while at the same time decrease the weight of such armor. The weight reduction is vital for reducing Warfighter fatigue and increasing mobility, while also improving the mobility and fuel efficiencies of armored vehicles.
MIT Develops Wireless, Wearable Sensor for Toxic Gas
Researchers from the Massachusetts Institute of Technology (MIT) have created low-cost sensors that will give smartphones and other wireless devices the ability to detect the presence of even the smallest amounts of toxic gas. The sensors are made out of chemically altered carbon nanotubes, which break away from the insulating material wrapped around them upon the detection of toxic gas. This activates a near-field communication (NFC) alert on the device connected to the sensor.
Researchers will be using the sensors, which are able to detect toxic gas as little as 10 parts per million in the air in as fast as five seconds, to create inexpensive and lightweight radio frequency identification, or RFID, badges that can be utilized for personal security and safety from toxic gases.
These RFID badges will have military applications, as they will be able to replace all the extra equipment that soldiers have to carry around to defend themselves against toxic gas, including choking and nerve agents.
Handheld sensors for explosives, deadly gases and illegal drugs
University of Utah engineers have developed a new type of carbon nanotube material for handheld sensors that will be quicker and better at sniffing out explosives, deadly gases and illegal drugs. Zang and his team found a way to break up bundles of the carbon nanotubes with a polymer and then deposit a microscopic amount on electrodes in a prototype handheld scanner that can detect toxic gases such as sarin or chlorine, or explosives such as TNT.
When the sensor detects molecules from an explosive, deadly gas or drugs such as methamphetamine, they alter the electrical current through the nanotube materials, signaling the presence of any of those substances, Zang says. “You can apply voltage between the electrodes and monitor the current through the nanotube,” says Zang, a professor with USTAR, the Utah Science Technology and Research economic development initiative. “If you have explosives or toxic chemicals caught by the nanotube, you will see an increase or decrease in the current.”
By modifying the surface of the nanotubes with a polymer, the material can be tuned to detect any of more than a dozen explosives, including homemade bombs, and about two-dozen different toxic gases, says Zang. The technology also can be applied to existing detectors or airport scanners used to sense explosives or chemical threats.
Future Soldiers Wearables
This can lead to decreasing the number of layers required for a bulletproof vest from 30 to 15, thereby creating a lighter piece of body armor that gives the user more maneuverability without sacrificing safety.
Not surprisingly, CNT fibers have already found their way into soft armor products such as the ones manufactured by AR500, Block Textiles, Amendment II, and NanoRidge (and their customer Riley Solutions, Inc. [RSI]).
Lawrence Livermore National Laboratory scientists and collaborators are developing a new military uniform material that repels chemical and biological agents using a novel carbon nanotube fabric. Sweat and air would be able to easily move through the nanotubes. However, the diameter of the nanotubes is smaller than the diameter of bacteria and viruses. That means they would not be able to pass through the tubes and reach the person wearing the suit.
For handling chemical warfare agents the CNTS are surface modified with a chemical warfare agent-responsive functional layer. Under direct chemical warfare agent attack, the material is designed to undergo a rapid transition from a breathable state to a protected state by closing the CNT pore entrance or by shedding the contaminated surface layer.
Explosive and Chemical Sensors
“Carbon nanotube (CNT) sensors are effective because we can leverage multiple properties (e.g., electrical, thermal, optical, chemical and structural) to determine what or how they will sense their environment. Additionally, CNTs could allow us to create flexible and even transparent sensors, as well as sensors with increasing sensitivity and specificity at a lower cost than traditional sensors, potentially simplifying actual designs and reducing manufacturing costs,” says Travis Earles from Lockheed Martin.
As an example, CNT fabrics are at the core of Lockheed Martin’s chemical sensor platform technology that can be designed to detect a wide range of gases and volatile organic compounds.
Chemical and Biological Weapon Protection
Current-day chemical and biological protective suits are passive solutions that are heavy, bulky, and fully sealed. They are not amenable to the wearer’s comfort, and tend to induce heat stress and fatigue. To address these issues, LLNL’s Dynamic Multifunctional Material for a Second Skin Project is developing the CNT-based fabric, that will have the ability to repel either chemical or biological agents that may by dispersed by enemy combatants.
The lightweight base CNT material provides permeability, as the pores created by the CNTs facilitate gas transport that is several orders of magnitude greater than pores of any other material. The CNTs would be modified by “functional group” materials that will have the capability to quickly and automatically detect and react to various agents, reversibly switching from a highly permeable mode to a protective mode, sealing off chemicals, but allowing for sufficient “breathability.” The layered protective membrane would either close off the CNT pores or shed contaminated layers. It is anticipated that such suits could be deployed as early as 2022
A team led by Lawrence Livermore National Laboratory (LLNL) and funded by the Defense Threat Reduction Agency (DTRA) is pursuing a variation on personal protective equipment for the military.
Energy Efficiency
The Power and Energy Strategy White Paper, prepared by the U.S. Army Capabilities Integration Center in 2010, outlined the increasing importance of energy to the base, the Warfighters, and their vehicles. An example of the concerns included in the paper is that of battery usage. Presently for a 72-hr mission, the average Warfighter carries about 70 batteries of 7 different types, weighing a total of approximately 16 lbs. The paper suggests a number of initiatives that should be pursued to address this and other aspects of power and energy, including a need for:
- Increased Energy Efficiency
- Decreased Weight of Energy Devices
- Innovative, Integrated Electrical Power/Energy Solutions, Ranging from Charging to Energy Harvesting.
CNTs can play a number of important roles toward achieving several of the Army’s goals. CNTs are proposed for use in a range of small primary and secondary batteries. At the anodes of lithium ion batteries, the high surface area afforded by CNTs increases the capacity and deliverable current and promises improved lifetime. These advantages should allow for a decrease in the number and weight of the battery load required per Warfighter. CNTs are also being investigated for use in lead-acid batteries, leading to longer life in standard vehicles, thereby decreasing maintenance. And as the Military Services transition part of their vehicle fleet to electric or hybrid power, high-capacity lithium ion batteries with CNT anodes will serve to increase the operating and service life of CNT battery cells.
Super-capacitors based on CNT technology are also being investigated as a lower-cost, lower-weight alternative to some of the batteries used by the Warfighter. If successful, these would enjoy a much longer cycle life than can presently be attained by rechargeable lithium ion cells. Additionally, solar cells, whether used in the field or in fixed installations, are an important means of generating electrical power and reducing the reliance on fossil fuels. Solar arrays, tents, and battery chargers are presently in use in the field by the military. The use of a CNT coating on solar cells or thermal devices, such as the device pictured in Figure 6, can increase their efficiency by reducing reflected light/heat, thereby capturing and producing energy more efficiently
Fighting metal corrosion
Military equipment like Tanks, gates, doors, wickets, buildings, locks and dams, towers are made from steel and prone to corrosion. Carbon nanotubes assemble into rope-like structures that create super durable protective coatings and are electrically active to quickly and effectively fill voids created by scratches and other abrasive actions that mar metal surfaces.
