DARPA’s Defense Sciences Office (DSO) identifies and pursues high-risk, high-payoff research initiatives across a broad spectrum of science and engineering disciplines and transforms them into important, new game-changing technologies for U.S. national security. Current DSO themes include frontiers in math, computation and design, limits of sensing and sensors, complex social systems, and anticipating surprise. DSO relies on the greater scientific research community to help identify and explore ideas that could potentially revolutionize the state-of-the-art.
Within DSO, we are leveraging efforts from our existing portfolio to discover novel COVID-19 therapeutics, develop environmental sampling for detecting the presence of SARS-CoV2 (the virus that causes COVID-19), and mitigate U.S. pharmaceutical supply chain challenges. These efforts will not only help address the current crisis but will also ensure that U.S. military and civilian populations are better protected against future pandemic threats, said Dr. Valerie Browning Director, DSO.
Over the past year, DSO has initiated five new major programs that will help the U.S. win important technology races in hypersonics, space, autonomy, energetics, and stabilization. The RIDE program will leverage recent DARPA investments in automation and artificial intelligence to significantly accelerate and systematize energetics research. Given that many of today’s state-of-the-art energetic materials are assembled from materials discovered nearly 100 years ago, we are excited to see what this new approach to energetics discovery will produce. Our new Habitus program represents a deliberate pivot within DSO to focus on deterrence and stabilization operations in areas that we refer to as Undergoverned Spaces (UGS). UGS are permissive environments that are particularly vulnerable to exploitation and/or influence from actors whose interests do not necessarily align with ours or our allies. Habitus seeks to capture local knowledge and make it available to military operators to provide an insider’s view that informs sound decision-making for stabilization and deterrence operations.
Defense Sciences Office (DSO) is referred to as “the DARPA’s DARPA
DSO, is referred to as “the DARPA’s DARPA,” for its focus on fundamental science breakthroughs, it’s materials science programs build on a heritage of materials research successes in semiconductors, superalloys, carbon fibers, composites, thermoelectric, and ceramics that have enabled advanced capabilities in many of today’s military systems as well as in civilian commercial applications including:
• Gallium Arsenide Integrated Circuits used in the Precise Lightweight GPS Receiver
• Advanced superalloy materials used in the engine for F-15 and F-16 aircraft
• Beryllium Mirrors for NASA’s Infrared (IR) Astronomical satellite Program
• Rare Earth Permanent Magnets for high-performance traveling wave tubes used in electronic warfare systems on F-15 aircraft, the Navy’s EHF Satcom Progam and cryocoolers for IR sensors on Cobra helicopters and F-18 aircraft
• Metal Matrix Composites for space-based antenna mast applications, including the antenna mast for the Hubble Space Telescope
• Precision, High-Performance Ceramic Bearings in gyros for the F-18, AV-8, F-16, several helicopters, and in the bearings for IR seekers for the Navy Missile Homing Improvement Program
• Silicon Carbide Particulate-Reinforced Aluminum for use as F-16 ventral fins and as the fan exit guide vanes for large turbofan engines used on the 777 commercial aircraft.
• Ceramic Composite Armor for protection of flight crews in C-141 transport aircraft flying in Bosnia against small arms fire and for application to light armored vehicles
• In situ Metal Matrix Composites for the compressor inner shroud for the F-22 fighter’s engine.
The DSO’s focus areas are:
- Mathematics, Modeling, and Design: Development and implementation of advanced mathematics and modeling tools for applications of interest to U.S. national security.Example topics include: Novel mathematical advances that accelerate discovery in physics, chemistry, and materials science; new approaches to electromagnetic modeling and simulation and techniques to enhance the capability for humans to understand, construct and optimize complex engineering systems.
- Physical Systems: Leading-edge experimental and/or theoretical research that advances understanding and capabilities for U.S. national security in the physical sciences. Example topics include: Exploring theoretical, experimental and/or technological boundaries of a topic/technical area to better anticipate technological surprise e.g., How far can we push the performance of optical and imaging systems? Are there fundamental principles that govern operation and limitations of machine learning systems? How can emerging gene modification tools affect national security in 5, 10 or 20 years?; emerging areas in quantum science, ranging from quantum information to novel photonic devices; new computational substrates optimized for solving complex problems; and new methods for identifying, synthesizing and utilizing molecules and molecular systems to demonstrate unique function/capability.
- Human-Machine Systems: Research to analyze, understand, and optimize human-machine/human-technology systems and system dynamics across a variety of application areas important for U.S. national security (e.g., materials, part and platform manufacturing, defense systems, human innovation systems and collaborative military systems).Success in this venture could radically magnify the capabilities of people to respond to increasingly complex problems in areas as diverse as military strategy, manufacturing, and human innovation.
- Social Systems: New methods, tools and approaches to explore and better understand human social systems and dynamics in a national security context.
Taken together, Tompkins said, DSO’s materials science portfolio points to a future featuring an exciting array of substances with unprecedented properties and capabilities. “All of these programs reflect a fundamental shift,” she said, “from bulk-process to architected materials—a shift we believe has the potential to introduce a new ‘Designer Age’ of materials development.”
What are we exploring now?
- Materials, structures and scientific capabilities for extreme environments (space, arctic, hypersonic and underwater)
- Ultra-large space structures: design, limits of stability, on-orbit manufacturing, new mission concepts
- New scientific methods for understanding and preventing corrosion
- Enhancing human learning and creativity through neuroscience and complex social system understanding
- Self-decontaminating materials and systems for harsh environments
- Metamaterials for use in high temperature environments
- Robust, reconfigurable, large-area metamaterials for compact dynamic imaging modalities
- Methods for up-conversion and amplification of photons in thin materials from infrared bands to visible wavelengths
- Understanding the fundamental limits in bandwidths of active antennas, such as non-Foster circuits, and how such capabilities could be employed within modest size, weight, and power constraints
- Material platforms for demonstrating robust switching of thermal emission over large areas with minimal power draw
- Quantum information processing with Noisy Intermediate Scale Quantum (NISQ) devices
- High-precision time distribution
- Photonic quantum information processing
- Sensing and metrology, quantum information science with atomic vapors
- Efficient optimization techniques for designing complex material formulations
- Novel synthetic approaches, including new electrochemical and photochemical approaches for addressing synthesis challenges such as rate and scalability
- Intersections of computation and mathematics with chemical systems to accelerate discovery
- New synthetic methodologies or materials systems for and from zero g-force environments
- Computational challenges that are not solvable with today’s classical and quantum computing systems
- Understanding how we can incorporate 2nd and 3rd Wave AI into multi-disciplined teams to increase collaboration and accelerate scientific discovery
- Using SET-based design methodologies to investigate environmental and operational effects on outer mold lines, leveraging rather than mitigating these effects, leading to revolutionary new platforms
- Developing mathematical representations that can be computable by non von Neumann computational architectures
- Exploring the limits of environmental sensing and how one might capture the information that is imprinted and left behind by natural and non-natural transient disturbances
- Developing subtle techniques that would allow us to determine whether or not a system is enhanced with AI
- Determining whether it’s possible to harvest, direct, shape, of transduce energy and momentum from the quantum background
- Improving AI’s ability to understand human and social systems
- Methods for sensing cultural and attitudinal alignment at the source of data collection to overcome mirror imaging and other cognitive biases in collection, analysis, and operations, and for operations in undergoverned spaces
- Tools for anticipating emergent asymmetries, opportunities, and vulnerabilities due to national-cultural influences on AI development
- Cognitive scientific approaches to understanding, certifying, and diagnosing issues to address the opacity of the AI “black box”
- Cognitive Systems Engineering to establish new whole-brain/embodied approaches for human-machine teaming, experiential transfer, and interface design in the age of AI and autonomy
- Discovering unintended physical interactions in complex cyber-physical systems during design
- Discovering analytic models from material structures and manufacturing processes to predict properties and discover fundamental limits
- Exploring new approaches to build multi-physics/multi-scale simulators faster while improving accuracy
- Novel approaches to neutron and gamma-ray generation with precise control of energy and direction
- Unconventional approaches to high efficiency photon detection that preserve photon energy information from infrared through gamma-ray energies
- Approaches to scalable/tailorable effects systems for force and population protection in stabilization operations and undergoverned spaces
- New capabilities for energy generation and storage in austere or disrupted environments
- Identifying the fundamental elements necessary for AI systems to have teaming competency
- Concepts that integrate AI into sensing to overcoming fundamental limits in sensing
- Self-consistent fusion of AI information in dynamic environment across multiple modalities
- AI-enabled real-time forecasting of complex dynamic processes
- Novel concepts exploiting complex dynamical natural or artificial phenomena to perform computation
Atoms to Product (A2P) program
The Defense Advanced Research Projects Agency is trying to change the way materials are structured and created, hoping to usher in the “Designer Age” of material science. Advances in materials have been key to achieving a wide range of critical, defense-related capabilities and DARPA is aiming to develop new materials that could eventually lead to revolutionary capabilities as well as miniaturization and assembly methods that would work at scales 100,000 times smaller than current state-of-the-art technology.
The burgeoning field of nanotechnology promises an indefinite range of capabilities in medicine, optics, communications, and other facets of applied science and engineering. On that front, the U.S. Defense Advanced Research Projects Agency’s (DARPA) Atoms 2 Products program (A2P) is funding 10 companies, universities, and institutions to develop mass-manufacturing techniques and technologies for functional products made up of nanoscale constituents.
One major challenge in developing new materials has been the difficulty of retaining and exploiting the unique characteristics that emerge in materials at the nanoscale (a few 10-billionths of a meter). Many materials demonstrate unique and potentially useful electrical, optical and tensile characteristics at these nearly atomic scales, but lose these traits when engineered into millimeter- or centimeter-scale products and systems. Atoms to Product (A2P) program seeks to develop bottom-up manufacturing technologies and processes to assemble nanometer-scale pieces, and integrate them into systems, components, or materials up to product scale in ways that preserve and exploit distinctive nanoscale properties.
This will allow “atomic-scale” behaviors including quantized current-voltage behavior, glueless adhesion, tunable light absorption, dramatically lower melting points and significantly higher specific heats, to be available in human-scale products and systems, and would offer potentially revolutionary defense and commercial capabilities. The program calls for closing the assembly gap in two steps: the assembly from atoms to microns and from microns to millimeters. Performers are tasked with addressing one or both of these steps and have been assigned to one of three working groups, each with a distinct focus area.
For both areas, DARPA is looking to make sure that nanoscale properties will be retained as products get larger and to develop assembly processes that can work fast enough to be practical and efficient.
“We want to explore new ways of putting incredibly tiny things together, with the goal of developing new miniaturization and assembly methods that would work at scales 100,000 times smaller than current state-of-the-art technology. If successful, A2P could help enable creation of entirely new classes of materials that exhibit nanoscale properties at all scales. It could lead to the ability to miniaturize materials, processes and devices that can’t be miniaturized with current technology, as well as build three-dimensional products and systems at much smaller sizes”, In the words of John Main, DARPA program manager.
DARPA selects 10 performers to develop technologies that bridge the existing manufacturing gap between nano-scale pieces and millimeter-scale components: Zyvex Labs, Richardson, Texas; SRI, Menlo Park, California; Boston University, Boston, Massachusetts; University of Notre Dame, South Bend, Indiana; HRL Laboratories, Malibu, California; PARC, Palo Alto, California; Embody, Norfolk, Virginia; Voxtel, Beaverton, Oregon; Harvard University, Cambridge, Massachusetts; and Draper Laboratory, Cambridge, Massachusetts.
Intelligent Materials Solutions. “Our initial project will be to control infrared light by assembling nanoscale particles into finished components that are one million times larger,” explains Adam Gross, the team leader working closely with Christopher Roper to bring the Atoms-to Products project to fruition. “We have already shown we can assemble two types of nanoparticles for the control of infrared light,” said Gross. “We assemble layer-upon-layer of spherical diffraction gratings. Our first milestone will be to assemble two types of sub-200 nanometer gratings into 210 micron assemblies that maintain their nanoscale properties.”
Achieving this next step will likely require a year out of the three-year program. Following this, the team will look into assembling these micro-scale subassemblies into millimeter scale products that hope to maintain the quantum effects and lower the melting points.
Nanoscale materials could free up frequency spectrum needed to connect for the Internet of Things
Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and Draper are developing a new approach to assembling nanoscale hardware that could overcome this challenge by enabling devices to generate and receive purer signals to reduce interference with other nearby transmissions. This could free up spectrum by reducing the need for space between frequencies that the Federal Communications Commission now assigns to different users, explained Draper’s Amy Duwel, technical director for the NanoLitz project. The Defense Advanced Research Projects Agency (DARPA) and the U.S. Air Force Research Laboratory are funding the NanoLitz work as part of the Atoms to Product (A2P) effort to find new ways to assemble nanoscale materials that cannot be accomplished with current techniques such as those used in the semiconductor and microelectromechanical systems (MEMS) industries or through chemical synthesis.
The results could be applied to tools that enable humans to scale sheer walls; stealth technology; and ultra-small position, navigation and timing devices. The NanoLitz approach braids microscopic wires to reduce heat loss, improve efficiency, and sharpen filter response. To operate at frequencies used in devices like smartphones, Roy Gordon, Thomas Dudley Cabot Professor of Chemistry and Professor of Materials Science at Harvard, is developing techniques for making wires up to 1,000 times smaller than those used today. The wires will be braided with techniques borrowed from MEMS and microfluidics. The team is also developing a DNA self-assembly method as a tool for manufacturing braids. That work is led by Vinothan Manoharan, Wagner Family Professor of Chemical Engineering and Professor of Physics; and Michael Brenner, Glover Professor of Applied Mathematics and Applied Physics and Professor of Physics, both at Harvard SEAS.
In parallel, Draper is developing a microfluidics-inspired approach for mechanically braiding the tiny wires that would be scalable to large numbers of wire at high throughput. Draper is also leading the efforts to model and design the Nanolitz wire to optimize electrical performance. The improved signal performance could also enable devices to transmit up to five times more data per channel, receive much fainter signal levels, and overcome interference that disrupts GPS signals, said Draper’s David Carter, NanoLitz program manager.
Nanometer to Millimeter in a Single System – Embody, Draper and Voxtel
Embody will concentrate on developing collagen nano fibers that can mimic natural ligaments to the medical recovery of soldiers for quicker and 50 percent lower cost that today. Current methods to treat ligament injuries in soldiers—which account for a significant portion of reported injuries—often fail to restore pre-injury performance, due to surgical complexities and an inadequate supply of donor tissue.
And as with all DARPA programs, they hope that their success will seep into the civilian world of sports injuries.
Draper: Radio Frequency (RF) systems (e.g., cell phones, GPS) have performance limits due to alternating current loss. In lower frequency power systems this is addressed by braiding the wires, but this is not currently possibly in cell phones due to an inability to manufacture sufficiently small braided wires.
Draper will concentrate of radio frequency subsystems to boost their range and global positioning accuracy by 20 times by assembling nanoscale braiding subassemblies first at the micron scale then finally at the millimeter scale in phase two. If successful, portable RF systems will be more power efficient and able to send 10 times more information in a given channel. Their technique will be to copy how DNA self-assemblies into an intertwined structure.
Voxtel and Oregon State University will concentrate on imitating nature’s ability to self-assembly multi-material structures using high-rate fluid-based processes by combining the synthesis and delivery of materials to inkjet-like three-dimensional (3-D) mixed organ and inorganic materials which retain the best qualities of both at a price lower than either alone. Historically, challenges relating to the cost of atomic-level control, production speed, and printing capability have been effectively insurmountable.
The goal is to assemble complex, 3-D multimaterial mixed organic and inorganic products quickly and cost-effectively—directly from atoms.
Boston University’s Atomic Calligraphy Technique
Developers at Boston University are using a microelectromechanical system (MEMS) with nanoscale precision to draw patterns on a silicon substrate smaller than 400 microns. The technique deposits atoms onto a surface using an automated stencil that incorporates a quick-response shutter system for precise control during atom deposition. So far, the team has demonstrated the ability to write the BU logo, infinity signs, spirals, and other intricate patterns using their atom-deposition apparatus. Surface patterning of human cells is a foreseeable application with regard to immunology research, as well as nanoscale printable circuit boards.
Fabrication of tunable infrared metamaterials using atomic calligraphy
Metamaterials with dynamically variable spectral response to incident radiation through the use of a deformable substrate have so far been limited to the IR and longer wavelength regimes. Such materials, with unit cells a few to tens of microns across, can readily be fabricated using existing lithography techniques. Extending these metamaterials to shorter wavelengths and into the visible spectrum requires a proportional shrinking of the unit cell to be patterned over a large area. The reduced structure size leads to a strong reduction in the throughput of the chosen fabrication technique.
Reeves, Jeremy; Stark, Thomas and others from Boston University have investigated the prospects for the use of atomic calligraphy to pattern arbitrary infrared metamaterials with high throughput. Atomic calligraphy provides a scalable technique for the manufacture of metamaterials with high precision while allowing for writing on a variety of substrates, including deformable materials. We consider the electromagnetic response of these tunable materials and possibilities to develop metamaterials with resonances in the visible spectrum.
Optical Metamaterial Assembly – Boston University, University of Notre Dame, HRL and PARC.
Nanoscale devices have demonstrated nearly unlimited power and functionality, but there hasn’t been a general- purpose, high-volume, low-cost method for building them.
Boston University will aim to build atomic-scale calligraphy techniques that can “spray-paint” with atomic accuracy for tunable optical metamaterials built on the ‘photonic” battlefield.
The University of Notre Dame will aim for parallel nano manufacturing techniques that enable optical metamaterials to be manufactured on-demand with specific ‘designer’ characteristics. Their technique will use optical tiles that can quickly assembled in different configurations using single-atom electrochemistry.
For the ND project, “Holographic Assembly of Reconfigurable Plasmonic and Photonic Elements” researchers are using 3D halographic assembly of nanoparticles lattices to develop microelement feedstocks with reconfigurable, heterogenous optical properties that can impart new functionality (like optical cloaking) at the macroscale.
Xerox PARC is creating the world’s first digital micro-assembly printer using micrometer-sized ink particles that can assembly centimeter-scale assemblies that maintains nanoscale properties for secure communications, surveillance and electronic warfare.
Flexible, General Purpose Assembly – Zyvex, SRI, and Harvard.
Zyvex is hoping to create microscale devices with nanoscale properties from the top-down and with atomic precision for ultra-sensitive sensors, threat detection, quantum communications and sand-grain sized atomic clocks.
SRI is aiming to create what it called “levitating micro-factories” that combine micro-electro-mechanical systems (MEMS) with pick-and-pace robot “swarms” that connect micro-scale subassemblies with nanoscale properties into millimeter-sized products ready for deployment.
Many high-impact, minimally invasive surgical techniques are currently performed only by elite surgeons due to the lack of tactile feedback at such small scales relative to what is experienced during conventional surgical procedures.
Harvard is creating a new era of millimeter-scale surgical tools 2D layer-by-layer composition processes to create complex meso-scale 3D devices for specific surgical procedures. Their goal is to allow surgeons to retain tactile feedback even when performing micron-scale surgeries.
Materials with Controlled Microstructural Architecture (MCMA) program
As a global force, the U.S. military is called upon to conduct missions that subject its platforms to extreme operational environments and structural loads. The endurance and performance of future Department of Defense platforms may call for the availability of materials with structural properties that significantly surpass current technology.
DARPA is pursuing other approaches to creating new materials with unique properties through its Materials with Controlled Microstructural Architecture (MCMA) program. This program seeks to control the architecture of material microstructures to improve structural efficiency and realize properties that traditionally aren’t achieved together in a single substance, such as the strength of steel and the weight of plastic.
The work could also help incorporate other important properties, such as high rates of heat diffusion for thermal management applications and tailorability of thermal expansion to enable joining of normally incompatible materials.
“What if the principles of construction used for large structures could be applied to material microstructures, allowing designers to engineer a material the way civil engineers design skyscrapers and suspension bridges?” asked DARPA program manager Judah Goldwasser. “That would allow us to achieve high-efficiency materials and could lead, for example, to vehicles that are one-tenth their current weight and able to travel ten times farther on a tank of gas.”
One potential benefit of applying control over the internal, nano-architecture of materials is that the materials may then be able to catalyze reactions or perform energy conversions, effectively becoming devices in and of themselves.
Materials for Transduction (MATRIX) program
Materials for Transduction (MATRIX) program is seeking new materials for energy transduction ( conversion of energy from one form into another), such as communications antennas (radio waves to electrical signals), thermoelectric generators (heat to electricity) and electric motors (electromagnetic to kinetic energy) that would result in new capabilities or significant size, weight, and power (SWAP) reduction for military devices and systems.
MATRIX will take a systems approach that integrates state-of-the-art materials science, predictive modeling methods, and domain-specific expertise to rapidly validate and optimize new functional architectures that offer transformative defense-related capabilities.
“The goal is not just to design materials for use in devices; we envision developing materials that, because of their energy-transforming properties, are effectively devices themselves” according to Jim Gimlett, DARPA program manager.
Some of the potential applications include
- Thermoelectrics (thermal/electric domains) used for Energy transfer, energy harvesting, thermal management, and refrigeration;
- Multiferroics (magnetic/electric domains) for enhanced sensors, antennas, actuators, micromotors, tunable RF and microwave components;
- Phase Change Materials (various domains) used in transducers, switches, sensors, and control devices.
Anticipated deliverables from the MATRIX program include materials, devices, and modeling tools that can enable new transduction capabilities with significantly higher performance; lower noise; and smaller size, weight and power than current state-of-the-art technologies.
DSO’s Extended Solids (XSolids) program
Materials with superior strength, density and resiliency properties are important for the harsh environments in which Department of Defense platforms, weapons and their components operate. Recent scientific advances have opened up new possibilities for material design in the ultrahigh pressure regime (up to three million times higher than atmospheric pressure).
Xsolids program takes aim at a different class of materials—those that currently can be made and exist only at ultrahigh pressures up to millions of times atmospheric pressure. Materials formed under ultrahigh pressure, known as extended solids, exhibit dramatic changes in physical, mechanical and functional properties and may offer significant improvements to armor, electronics, propulsion and munitions systems in any aerospace, ground or naval platform.
These new “polymorphs” may provide significant performance enhancements in areas as diverse as semiconductor electronics and propulsion, and in structural applications ranging from aerospace to ground vehicles. “The discovery and fabrication of new materials has long been based on the application of heat,” said Goldwasser. “The development of high-pressure chemistry—or barochemistry—could open up a new era in materials discovery and development featuring an entirely new palette of materials for exploitation.”
Early work already hints at unique materials and properties that may emerge when everyday gasses such as carbon dioxide as well as silicon- and carbon-based solids are compressed under extreme conditions, Goldwasser noted. But because their synthesis and stabilization is so demanding, production of these materials for practical use has proven difficult. So in addition to materials discovery, XSolids is researching processing techniques to make their fabrication practical.
The Defense Advanced Research Projects Agency (DARPA) Defense Sciences Office (DSO) is requesting information on scalable techniques for the synthesis of extended solid materials characterized by extensive covalent bond networks. Extended solid materials include polymorphs and/or phases of metals, intermetallics, oxides, nitrides, and carbides.
The DARPA Extended Solids (XSolids) program has identified a number of materials with exceptional properties that are stable at ambient temperatures after the synthesis pressure has been released. For example, tough B 4 C ( J. Mater. Chem. C, 2015, 3, 11705; Chem. Mater., 2015, 27, 2855; J. Phys. Chem. Lett., 2014, 5, 4169) and a direct-bandgap silicon polymorph Si 24 ( Nature Materials, 2015, 14, 169) were recently reported. These materials currently require high pressures (>1 GPa) for fabrication. Such high-pressure conditions can only be achieved in diamond anvil presses that, even at large scale, produce only extremely small quantities (<1 mg) of material over the course of several hours.
The XSolids program has pioneered the use of metastable synthetic intermediates, but even these approaches ultimately require extreme temperatures and pressures that are intrinsically not scalable to continuous or large-scale batch production. Broadly, scalable production is only possible if the extended covalent bond networks characteristic of extended solids can be obtained using processes that are accessible at near or below atmospheric pressure and at temperatures below 1000° C. Scalable production technologies for the synthesis of extended solids are needed to make practical applications possible.
If the program is successful, it will create breakthrough improvements in properties such as strength, stiffness, energy content, thermal conductivity, electromagnetic and optical properties, with associated performance improvements in a wide range of defense applications.
While A2P, MATRIX and XSolids all address in various ways the challenge of scaling innovations from smaller to larger dimensions, another DSO materials program is addressing the challenge of how to add precision to the production of extremely thin films of substances.
Local Control of Materials Synthesis (LoCo) program
DSO’s Local Control of Materials Synthesis (LoCo) program seeks to advance thin-film materials and surface coatings, which are used in military applications ranging from optics to advanced electronics.
Despite decades of work, methods to enable atomic through millimeter-scale control over structure and properties of materials deposited on surfaces are still underdeveloped. For example, structural organization of high-value thin films is typically controlled by high-temperature deposition or annealing, but the high temperatures used during thin-film synthesis and deposition exceed the limits of many DoD-relevant substrates, restricting application opportunities. LoCo program researchers are developing new strategies and tools as a first step toward ordered materials deposition at or near room temperature.
Performers in DARPA’s Local Control of Materials Synthesis (LoCo) program are developing new strategies and tools as a first step toward ordered materials deposition at or near room temperature. Recent innovations include : (1) development of new high-flux/low-temperature plasmas for use in large-scale manufacturing processes and (2) a new atomic layer deposition strategy that facilitates film deposition via a write/edit approach.
“A growing array of technologies, including flexible electronics and even some biological systems such as brain-machine interfaces, depend on thin films with very precise behaviors, including surface mobility, optical clarity and reaction energy. But conventional thin films lose their value if they can be applied only with traditional, high-temperature deposition techniques,” said DARPA program manager Tyler McQuade. “Because so much of chemistry happens at the surfaces where two materials meet, we’re confident that the development of alternative methods for depositing films on substrates could open up a new world of material possibilities.”
Z-Man Program Demonstrates Human Climbing Like Geckos
DARPA’s Z-Man program has demonstrated the first known human climbing of a glass wall using climbing devices inspired by geckos. The historic ascent involved a 218-pound climber ascending and descending 25 feet of glass, while also carrying an additional 50-pound load in one trial, with no climbing equipment other than a pair of hand-held, gecko-inspired paddles.
The project was inspired by the biological properties of geckos, whose toes allow the animal to hang by a single toe from nearly any surface. In the future, U.S. warfighters will be able to scale any wall while carrying a full combat load.
Geckos can climb on a wide variety of surfaces, including smooth surfaces like glass, with adhesive pressures of 15-30 pounds per square inch for each limb, meaning that a gecko can hang its entire body by one toe. The anatomy of a gecko toe consists of a microscopic hierarchical structure composed of stalk-like setae (100 microns in length, 2 microns in radius). From individual setae, a bundle of hundreds of terminal tips called spatulae (approximately 200 nanometers in diameter at their widest) branch out and contact the climbing surface.
A gecko is able to climb on glass by using physical bond interactions—specifically van der Waals intermolecular forces—between the spatulae and a surface to adhere reversibly, resulting in easy attachment and removal of the gecko’s toes from the surface. The van der Waals mechanism implied that it is the size and shape of the spatulae tips that affect adhesive performance, not specific surface chemistry. This suggested that there were design principles and physical models derived from nature that might enable scientists to fabricate an adhesive inspired by gecko toes.
The novel polymer microstructure technology used in those paddles was developed for DARPA by Draper Laboratory of Cambridge, Mass.