What do carbon nanohorns, photonic band gap materials, electroactive polymers, and electrospun second skin have to do with logistics? They very well may provide the Army with lightweight, reliable systems that revolutionize how logisticians support the warfighter.

Editor’s Note: This is the second article in a three-part series on future technology and its potential impact on logistics. The first article, in the July–August issue, introduced the Revolution in Atoms, Molecules, and Photons (RAMP) and explored the implications of RAMP for energy production and delivery. This article introduces the extraordinary “designer” materials that RAMP research promises and explores the implications of designer materials for improving equipment readiness and reducing demands on the supply chain and distribution processes. The final article, in the November–December issue, will address research and development initiatives that are leading to revolutionary capabilities in “knowledge on demand” that will “Connect the Logistician” globally.

Aerogel is 99.38 percent air (above), but it can hold 4,000 times its own weight (for instance, the brick below) and act as a heat barrier (below the brick, protecting crayons from a torch).

As a nation at war, the United States must sustain its technological superiority if it is to maintain its dominance on the battlefield. Our forces, faced with an extremely adaptive enemy that ignores territorial boundaries, need novel, robust capabilities that are not easily countered. Research being conducted at the atomic, molecular, and photonic levels offers the means to design materials with revolutionary properties. These materials in turn will make possible equipment and capabilities that will assist in the triumph over our enemies.

For example, the way molecules with various shapes and surface features organize into patterns on the nanoscale level determines important material properties, including electrical conductivity, optical qualities, and mechanical strength. By controlling how that nanoscale patterning unfolds, researchers are learning to design new materials with remarkable properties. It is these revolutionary “materials by design” that will provide our forces with materials that are lightweight, reliable, and superconducting and that possess other properties that will enable new and greater capabilities. Researchers who once dreamed of making molecular-scale versions of transistors, wires, and other micro-electronic components on chips are now seeing this done routinely throughout the world.

Materials by Design

The emerging fields of nanoscience and nano-engineering are leading to unprecedented understanding and control over the fundamental building blocks of all physical things. This development is likely to change the way almost everything—from vaccines to computers to vehicles to objects not yet imagined—is designed and built. One group of these “designer” materials is called metamaterials.

Metamaterials are artificially constructed materials with qualities and responses that do not occur in nature. The functions of these new materials derive from extrinsic inhomogeneities (nonuniform structures) that can take many forms, including voids, particles, wires, and layers, and that can create structures whose properties transcend those of natural materials or any of their constituents. High-performance, low-frequency (less than 1 megahertz) magnetic metamaterials are being researched and developed for use in power electronics, electronic propulsion, and power generation. Novel high-frequency (greater than 1 megahertz) metamaterials with superior microwave and optical properties are being researched and developed for communication, radar, and wireless-power-transfer applications.

Electroactive polymers can operate like biological muscles.

Metamaterials possess amazing characteristics. Some of these materials turn our traditional perspective of the world upside down. “Left-handed” metamaterials are a case in point. For example, at an early stage in life, we learn that extension cords, which are made of metal wires, are used to conduct electricity from the wall outlet to an appliance such as a lamp, television, or toaster. We also learned to associate electrical conductivity with metals, normally the copper in extension cords. However, RAMP research has produced designer materials that fly in the face of our long-held understanding that materials such as plastics cannot and do not conduct electricity.

With the advent of materials-by-design research and the discovery of a category of materials known as left-handed metamaterials (which possess negative mirror-image, or “left-handed,” properties compared to naturally existing materials), our understanding of material properties is quickly changing. In other words, it may now be possible to produce plastic metamaterials that are superconductors of electricity. Since plastics generally are significantly lighter than electrical conducting metals, it is now conceivable that the traditional metal electrical wiring in vehicles and equipment could be replaced with plastic wiring. Imagine the weight reduction in a vehicle that uses lightweight plastics instead of the traditional metal wires to conduct electricity.

The benefits of left-handed metamaterial plastics include not only the obvious reduction in overall system weight but also orders-of-magnitude reductions in electrical resistance resulting from their superconducting properties. Large drops in electrical resistance translate directly into reduced thermal (heat) buildup and major increases in the mean time between failures of electrical components. This, of course, is very desirable to both combat forces actively engaged on the battlefield and the personnel who maintain the combat readiness of their equipment.

As we design new combat and combat support systems, it seems prudent that we consider these new plastic metamaterials for several reasons—

• Increased availability of combat-ready vehicles and equipment.
• Reductions in the life-cycle operations and sustainment costs for vehicles and equipment that could save billions of dollars.
• Decreased demand for logistics support, with considerable secondary effects: Fewer parts will need to be procured, stored, shipped, distributed, accounted for, and tracked; throughput demands on supply chain and distribution processes will be reduced, including decreased fuel consumption associated with reduced vehicle weight; and requirements for maintainers on or near the battlespace will decrease.

An optical microchip incorporates microphotonic devices made of PBG materials.

Photonic Band Gap Materials

One type of metamaterial of particular interest to logisticians is photonic band gap (PBG) materials, which could significantly improve reliability in electronic components. PBG materials offer simplification and improved efficiencies in microchips. Recent advances in microstructuring technology have allowed controlled engineering of three-dimensional PBG structures at the near-infrared, as well as the visible, regions of the electromagnetic radiation spectrum. Light in certain engineered dielectric microstructures can flow in a way similar to electrical current in semiconductor chips. [“Dielectric” refers to a material that is an electrical insulator or that can sustain an electrical field with a minimum dissipation of power.] These microstructures provide a foundation for the development of novel microphotonic devices and the integration of such devices into an optical microchip. (See photo above.)

The current state of PBG research suggests that this field is at a stage comparable to the early years of semiconductor technology, shortly before the invention of the solid-state electronic transistor. If this analogy holds, we may find PBG materials at the heart of a 21st century revolution in optical information technology, similar to the revolution in electronics that occurred over the latter half of the 20th century.

PBG materials are being used to revolutionize electronic chips and radio frequency identification (RFID) tags. (The final RAMP article in the November–December issue of Army Logistician will discuss this subject in greater detail.)

Electroactive Polymers

The recent emergence of electroactive polymers (EAP) material with large displacement response changed the understanding of these materials and their potential capability. [“Displacement response” refers to a substance’s response to being moved from a normal position.] The main characteristic of EAP is their operational similarity to biological muscles, particularly their resilience and ability to induce large actuation [bringing into action] strains. (See photo at far left.) Unique robotic components and miniature devices are being explored in which EAP serve as actuators to achieve new capabilities.

The most attractive feature of EAP is their ability to emulate biological muscles with a high degree of toughness, large actuation forces, and inherent vibration damping. This similarity, which gained EAP the name “artificial muscles,” offers the potential of developing biologically inspired robots. Such biomimetic robots come in various sizes and shapes and can be made highly maneuverable, noiseless, and agile. Effective EAP also offer the potential of turning science fiction ideas into reality much faster than would be feasible with any other conventional actuation mechanisms.

Cagey Crystals and Aerogel

Cagey crystals are materials that are characterized by randomly shaking atoms. They could be crucial to developing materials that are able to conduct electricity but not heat. That ability is one key to improving the reliability of electrical components.

This nanotube was formed by joining an “even” rolled graphic sheet (above the joint), which is predicted to be semiconducting, to a “spiral” rolled sheet (below the joint), which is predicted to show metallic behavior. Theory predicts that this would act as a nanodiode.

Aerogel is a transparent material that is 99.38 percent air and can hold 4,000 times its own weight without deformation. (See photos on pages 24 and 25.) It is a heat barrier that could be used as a heat shield in combat vehicles or as a thermal blanket for munitions. Aerogel is commercially available today and could help to solve the weight issues associated with the Army’s Future Combat Systems.

Nanoscale Materials

Nanoscale materials, such as nanotubes, nanopipettes, nanocones, and nanohorns, are finding applications in electronics. These applications offer such desirable benefits as dramatic reductions in electrical resistance and the associated thermal buildup that is a major cause of failure in electronic components. Nanodiodes hold the promise of having a 20,000 times reduction in electrical resistance compared to today’s electrical circuits. (See photo on page 27.) Similar applications of superconducting carbon nanotubes in batteries significantly extend the usable energy in those batteries. This application of carbon nanotubes is being used today as nearly 60 percent of all current cell phone batteries incorporate carbon nanotubes.

Extending the usable energy in batteries will increase battery life, which will reduce the frequency of recharging or replacing batteries on the battlefield and the demand for battery resupply by logisticians.

Carbon nanohorns are used to make a tiny fuel cell with 10 times the energy capacity of a lithium battery. (“Pt” is the chemical symbol for platinum, “C” for carbon, “H” for hydrogen, and “O” for oxygen; “e” stands for energy, and "nm" for nanometer.)

Carbon Nanohorns

Scientists have developed a tiny fuel cell for mobile terminals using the minute and unique structure of the carbon nanohorn. (See diagram above.) This fuel cell has attained significant improvements over conventional activated-carbon terminals. The carbon nanohorn fuel cell has about 10 times the energy capacity of a lithium battery. This fuel cell could power continued use of a personal computer for several days, as opposed to only several hours. Materials such as carbon nanohorns offer the same logistics benefits as other nanoscale materials: greatly reduced requirements for conducting energy resupply missions.

NASA is exploring a possible transition from the bulky 300-pound spacesuit of the Apollo era to a "second skin" suit for Mars exploration.

Electrospun Second Skin

Future space explorers may apply a spray-on “second skin”—an organic, biodegradable layer offering protection in extremely dusty planetary environments. Second-skin spacesuit research is supported by the National Aeronautics and Space Administration (NASA) Institute for Advanced Concepts. (See photo above.)

The microfine fibers produced by electrospinning randomly collect into thin, nonwoven fiber mats that behave like microporous membranes. The objective of the second-skin initiative is to use electrospinning to produce seamless garments that perform multiple functions, such as providing flammable, chemical, and environmental protection. This will be done by blending the fibers into electrospinlaced layers in combination with polymer coatings. The second skin will incorporate electrically actuated artificial muscle fibers to enhance human strength and stamina.

This spray-on coating also could be used to protect cargo shipments or as a second skin to enhance logisticians’ physical strength for handling cargo. It could augment Soldiers’ strength to the point that the need for materials-handling equipment to handle certain configured loads or classes of supply might be eliminated. Electrospun coating also could be used to hermetically seal cargo and thus protect it from the environment, dust, heat, cold, and humidity. Since this material biodegrades, it could eliminate the traditional problem of residual dunnage. NASA’s Institute for Advanced Concepts and the Army’s Natick Soldier Systems Center are actively researching and developing the manufacturing technologies that will provide electrospun polymers.

Nano-technology has given us the tools . . . to play with the ultimate toy box of nature—atoms and molecules. Everything is made from it . . . The possibilities to create new things appear limitless. — Horst L. Störmer, Lucent Technologies and Columbia University, 1998 Nobel Prize in Physics

Other Designer Materials

Materials with an unprecedented combination of strength, toughness, and lightness will make all kinds of land, sea, air, and space vehicles and associated combat equipment lighter and more fuel efficient. Aircraft designed with lighter and stronger nanostructured materials will be able to fly longer missions and carry more payload. Plastics that wear less, because their molecular chains are trapped by ceramic nano-particles, will lead to the development of materials that last a lifetime. Some long-term researchers are working to create self-repairing metallic alloys that automatically fill in and reinforce tiny cracks that otherwise can grow and merge into larger ones. These alloys could help prevent catastrophic equipment and component failures.

Other materials of interest to the Army logistician include—

• Molecular layer-by-layer crystal growth, which can be used to make new generations of more efficient solar cells.
• Selective membranes, which can desalinate seawater inexpensively or provide other means of producing potable water.
• Chameleon-like camouflage, which can change shape and color to blend in anywhere, anytime.
• Blood substitutes.

The pervasive RAMP research and development that has been, and is currently being, conducted will bring about the advent of materials by design. Materials such as photonic band gap, electroactive polymers, cagey crystals, aerogels, and others offer the promise of increased component and material reliability; novel sources of energy; human-like robots capable of performing complex work; electrospun coatings that not only protect cargo but also protect and enhance the strength of Soldiers; and new means to communicate. As Army logisticians, we should be prepared to exploit the potential benefits that designer materials offer.
ALOG

David E. Scharett is a senior research scientist with the Pacific Northwest National Laboratory on assignment from the Department of Energy to the Army Logistics Transformation Agency at Fort Belvoir, Virginia. A command pilot with experience in both fixed- and rotary-wing aircraft, he has over 37 years of Government service. He has a bachelor’s degree in engineering from Virginia Polytechnic Institute and State University and a master’s degree from Golden Gate University and is a graduate of the Air War College.

Robert E. Garrison is a logistics management specialist with the Army Logistics Transformation Agency, Future Logistics Division, Science and Technology Team, at Fort Belvoir, Virginia. A recently retired chief warrant officer (W–5) with over 32 years of active service in the Army, he has an associate’s degree in general studies from the University of Maryland, a bachelor’s degree in vocational education from Southern Illinois University, and a master’s degree in general administration from Central Michigan University.