Scanning tunneling microscopy (STM) has revolutionized the fields of heterogeneous catalysis and environmental sciences by providing unique insights into the atomic-scale structure of model catalysts. For the first time, STM has revealed the structure of active sites, including steps, kinks, and special atomic geometries in compounds. It has provided images of atomic scale dynamic processes, including diffusion and reactions. STM can operate in environments of gases and liquids, as found in real life and in industrial processes. We illustrate these unique capabilities with examples and how the information obtained can lead to industrially relevant information and help the design of new catalysts.

Thin-film piezoelectric lead zirconate titanate (PZT) is one of the most efficient electromechanical coupling transducer materials currently available for microelectromechanical systems (MEMS). This article reviews piezoelectric MEMS (piezo MEMS) technologies using PZT thin films in radio frequency (RF) devices for communications and radar applications and in the emerging field of millimeter-scale robotics. The electromechanical material properties of thin-film PZT uniquely enable insect-inspired and insect-scale autonomous robots. Recent progress on large force and displacement actuators for robotic leg joints, compact and high torque ultrasonic motors, and bioinspired millimeter-scale flapping wing platforms will be presented. The use of thin-film PZT to achieve high performance and low-voltage RF MEMS switches, ultralow power consumption nanomechanical logic circuits, and high coupling and low loss resonators, filters, and transformers are also reviewed.

In the past 15 years, stretchable electronic circuits have emerged as a new technology in the domain of assembly, interconnections, and sensor circuit technologies. In the meantime, a wide variety of processes using many different materials have been explored in this new field. In the current contribution, we present an approach inspired by conventional rigid and flexible printed circuit board (PCB) technology. Similar to PCBs, standard packaged, rigid components are assembled on copper contact pads using lead-free solder reflow processes. Stretchability is obtained by shaping the copper tracks as horseshoe-shaped meanders. Elastic materials, predominantly polydimethylsiloxanes, are used to embed the conductors and the components, thus serving as a circuit carrier. We describe mechanical modeling, aimed at optimizing the build-up toward maximum mechanical reliability of the structures. Details on the production process, reliability assessment, and a number of functional demonstrators are described.

We review the recently introduced technique of atomic-resolution chemical mapping in scanning transmission electron microscopy (STEM) based on energy-dispersive x-ray spectroscopy. Working at the atomic level is facilitated by ultrasensitive energy-dispersive x-ray detectors in combination with Cs-correction of the STEM probe. Details of the experimental implementation are discussed, and a theoretical framework within which the measured results can be understood is described. Three case studies are presented: the analysis of specimens of GaAs and SrTiO3, as well as examination of an interface between SrTiO3 and PbTiO3. Detailed theoretical simulations of the imaging process show that the projected positions of elements in atomic columns can be directly deduced from the chemical maps. For the core shells used, the effective ionization interaction is local and generally localized in the vicinity of the atoms being ionized. The local nature of the effective ionization potential means that this is an incoherent mode of imaging, akin to Z-contrast imaging but with additional chemical information.

There has been explosive growth in the performance and consequential adoption of atom probe tomography in the past decade, which was fueled by the development of the commercial local-electrode atom probe (LEAP) and technologies for specimen preparation. The LEAP introduced to atom probes orders-of-magnitude increases in data collection rates and field of view while improving mass resolution and greatly improving ease of use. These developments constitute the second revolution in the field since the invention of the atom probe in 1967 and atom probe tomography in 1973: the invention of the three-dimensional atom probe was the first revolution. This article seeks to put this second revolution into historical perspective by recounting the essential developments that led to this point. In particular, the role of Erwin Müller, the inventor of the atom probe and related instruments, is highlighted. From the invention of the field emission electron microscope to the field ion microscope to the atom probe and beyond, he created a field of microscopy that is thriving today. Next, the state of the art in atom probe instrumentation is illustrated with a current application. Finally, a brief look toward future developments is provided, which may include superconducting detectors and integration of atom probes with transmission electron microscopes.

The high sensitivity of electron energy-loss spectroscopy (EELS) for detecting light elements at the nanoscale makes it a valuable technique for application to biological systems. In particular, EELS provides quantitative information about elemental distributions within subcellular compartments, specific atoms bound to individual macromolecular assemblies, and the composition of bionanoparticles. EELS data can be acquired either in the fixed beam energy-filtered transmission electron microscope (EFTEM) or in the scanning transmission electron microscope, and recent progress in the development of both approaches has greatly expanded the range of applications for EELS analysis. Near single atom sensitivity is now achievable for certain elements bound to isolated macromolecules, and it becomes possible to obtain three-dimensional compositional distributions from sectioned cells through EFTEM tomography.

Research in ABO3 perovskite oxides ranges from fundamental scientific studies in superconductivity and magnetism to technologies for advanced low-power electronics, energy storage, and conversion. The breadth in functionalities observed in this versatile materials class originates, in part, from the ability to control the local and extended crystallographic structure of corner-connected octahedral units. While an established paradigm exists to alter the size, shape, and connectivity of the octahedral building blocks in bulk materials, these approaches are often limited to certain subsets of the allowed perovskite archetypes and chemistries. In this article, we describe emerging routes in thin films and multilayer superlattices enabled by epitaxial synthesis aimed at engineering the octahedral connectivity—rotational magnitudes and patterns—to reach unexplored portions of the crystallographic structure–property phase space for rational materials design. We review three promising chemistry-independent strategies that provide a handle to tune the octahedral connectivity: epitaxial strain, interfacial control at perovskite/perovskite heterojunctions, and rotation engineering in short-period superlattices. Finally, we touch upon potential new functionalities that could be attained by extending these approaches to static and dynamic manipulation of the perovskite structure through external fields and highlight unresolved questions for the deterministic control of octahedral rotations in perovskite-structured materials.

This article shows how the scanning transmission electron microscope provides a Z-contrast image (where Z is atomic number) that is often directly interpretable and can show higher resolution than a phase-contrast image. It represents an incoherent mode of imaging, similar to that described by Lord Rayleigh for the optical microscope over a century ago. Today, resolution has reached a half Ångstrom, and spectroscopic analysis of individual atomic columns, even of individual atoms in two-dimensional materials, has become possible.

Extracellular matrix (ECM)-based materials used for neural interfaces allow for prolonged effective interaction between foreign devices and the neural cells in vivo because they mimic the natural environment. This review will highlight studies that have demonstrated how ECM-based materials can benefit neural interfacing applications as neural electrode coatings, scaffolds, and nanoparticle (NP) coatings. The performance of neural electrodes can degrade from inflammatory response as indicated by the signal obstruction between neurons and electrodes from glial scar formation during prolonged implantation. ECM materials can mitigate an inflammatory response because they are naturally biocompatible and biodegradable. Scaffolds composed from ECM-based materials have the characteristic length scale and biochemical cues that promote directional neural cell growth. ECM-based scaffolds can also be utilized as drug delivery vessels to infuse the neural tissue with neural growth factors and anti-inflammatory cytokines. The NPs currently employed for drug delivery and imaging use various ECM-based coating materials that shield them from the neural cells because many types of NPs are cytotoxic. As demonstrated by these three neural interfacing applications, ECM-based materials are very promising candidates for the development of next-generation neural regeneration and therapeutic devices.

Research in functional materials is frequently driven by a desire to make informed choices in the quest for better, more effective materials. A great deal of recent attention has been focused on the modalities of how such informed choices can themselves be made in a better, more effective manner. The examples presented here examine some of these modalities, emphasizing the nexus between new synthesis, computational design and analysis, growth in high purity forms, and finally, end-use in terms of either application or of significant property measurement. The illustrations, many drawn from the recent literature, commence with the role that theory has played, both in property prediction and concomitant materials selection, in the areas of multiferroics and topological insulators. The importance of materials quality is emphasized, using examples from observation of the fractional Quantum Hall Effect, where new science has emerged as a result of improved materials. In the area of organic electronics, prospects for advancing the field are suggested, as are future directions in nanoscience. While the examples chosen here point to developments that require a highly collaborative “systems” approach to materials, the role that serendipity plays is not ignored.

Plasmonics aims at combining features of photonics and electronics by coupling photons with a free-electron gas, whose subwavelength oscillations (surface plasmons) enable manipulation of light at the nanoscale and engender the exciting properties of optical metamaterials. Plasmonics is facing a grand challenge of overcoming metal losses impeding its progress. We reflect on the reasons why subwavelength confinement and loss are intimately intertwined and investigate the physics of loss in conductors beyond the conventional Drude model. We suggest that commonly used noble metals may not be the best materials for plasmonics and describe alternate materials such as transparent conducting oxides and transition metal nitrides. We consider the prospects of compensating the loss with gain materials and conclude that the so-far elusive solution to the loss obstacle lies in finding better materials with lower losses.

Moore’s law of transistor scaling, the exponential increase in the number of complementary metal oxide semiconductor (CMOS) transistors per unit area, continues unabated; however, computer clock speeds have remained frozen since 2003. The development of a new digital switch, the piezoelectronic transistor (PET), is designed to circumvent the speed and power limitations of the CMOS transistor. The PET operates on a novel principle: an electrical input is transduced into an acoustic pulse by a piezoelectric element which, in turn, is used to drive a continuous insulator-to-metal transition in a piezoresistive element, thus switching on the device. Performance is enabled by the use of key high response materials, a relaxor piezoelectric, and a rare-earth chalcogenide piezoresistor. Theory and simulation predict, using bulk material properties, that PETs can operate at one-tenth the present voltage of CMOS technology and consuming 100 times less power while running at multi-GHz clock speeds. A program to fabricate prototype PET devices is under way.

Insects constitute the most diverse and populated subclass of animals, with two million species identified. They also display a vast diversity of morphological and functional adaptations that allow them to thrive in various environments, which enables them to fly, swim, or walk nearly anywhere. Insects can be regarded as highly efficient and robust bio-machines, a precious source of material and information for bioinspired miniature technological devices. Yet, to date, little study of the functionality of insects has been undertaken with modern nanotechnology tools. Atomic force microscopy (AFM) is a technique generally used to study surface properties of materials at the nanoscale. Recently it has been shown that the AFM method can be extended to study complex living organisms, cells, and even entire animals, such as insects. AFM has demonstrated the feasibility of recording surface oscillations with sub-Angstrom spatial and sub-millisecond temporal resolutions while positioning the AFM probe at different parts of an insect with nanometer precision. In effect, it enables the AFM to function as a nanostethoscope. This article describes how such a nanostethoscope can be used to study the material properties, physiological reactions, and sensing mechanisms of insects.

Industry is increasingly aware that sustainability combines environmental, societal, and economic considerations in product development and that this linkage, while driving improved performance, can pose both a business opportunity and a challenge. On one hand, innovations make good business sense by bringing new products to supply a growing market demand for sustainable goods. On the other hand, new regulatory standards demand cleaner, less-toxic products, which can be difficult to develop economically, and require an agreed-upon infrastructure to demonstrate compliance, which can also be difficult and expensive. In this article, we discuss how measurements, standards, and data, being developed and deployed worldwide by national metrology institutes (NMIs) and standards-developing organizations (SDOs), are helping industry enable the sustainable use of materials. Examples include bio-based polymers, lightweight automobiles, fly-ash-based concrete, and lead-free solders. Measurements, standards, and data also support energy efficiency and renewable energy and ease industry compliance with new and emerging regulations, including those that demand less-toxic components.

Graphene is a two-dimensional material with unique properties, such as superb mechanical strength and carrier mobility. Similarly to semiconductors, however, graphene is not very useful for applications in its pristine form; rather, it must be “functionalized” through judicious manipulation of defects, impurities, and adsorbates. In this article, we provide an overview of the intrinsic defects in graphene, such as vacancies, interstitials, and line defects, and their potential role in transport and other properties. We also discuss impurities and adsorbates that can act as dopants to enhance carrier densities, controlling n- and p-type conduction for transistor applications, and can serve as reactive sites for catalytic and sensor applications. Although functionalization holds significant promise, realization of that potential remains an open pursuit.

The cost and performance of materials have traditionally been the primary factors considered by designers of consumer products. Recent attempts to quantify the environmental sustainability of such products have stimulated the development of methods for assessing the reserves of raw materials compared to the demand for their use in manufacturing and impacts on energy resources. To a much more limited extent, these strategies also evaluate how chemical toxicity, arising from material production, use, and disposal, affects human and environmental health. The mechanisms and adverse impacts of toxic effects vary widely at different points within material life cycles, making it difficult to establish internally consistent methods and weighting criteria for quantitative evaluation of the environmental liability of consumer products. This article reviews advances in the methodology and application of health and ecological impact assessments of materials used in consumer products and argues for a stronger integration of toxicity metrics into materials informatics databases.