Protection and aesthetics are the two common dimensions or attributes typically associated with textiles as clothing. However, with the rapidly changing needs of today's consumers, a third dimension is emerging—that of “intelligence”—that is being integrated into fabrics to produce interactive textiles, or i-textiles. This new class of wearable electronic systems is being designed to meet new and innovative applications in the military, public safety, healthcare, space exploration, sports, and consumer fitness fields. In this article, the concept of i-textiles is presented, along with the building blocks for its realization. This is followed by an overview of the design and development of the Smart Shirt, an “intelligent” garment that provides an extremely versatile framework for the incorporation of sensing, monitoring, and information-processing devices. The key applications of the Smart Shirt technology and their impact in transforming healthcare are discussed. Finally, the need to advance this paradigm and identify opportunities to transform passive textiles into the new generation of interactive, or “smart,” textiles is discussed.

Neutrons from collisions of cosmic rays with the nuclei of atoms in the atmosphere are an irremovable external radiation that causes single-event upsets in microelectronic devices. Predicting soft error rates requires knowledge of the flux and energy distribution of the cosmic-ray-induced neutrons. This article reviews cosmic-ray neutrons in the atmosphere and on the ground, the factors that determine their intensity, and recent calculations and state-of-the-art measurements of neutron spectra covering 12 decades of energy, from the thermal energy range up to 10 GeV.

This article reviews the fabrication technologies and optical characteristics of silica-based planar lightwave circuits (PLCs) on Si developed for photonic networks based on wavelength-division multiplexing (WDM). While there have been various planar optical waveguides made with different materials, silica-based PLCs are the most suitable for constructing practical devices because of their excellent design flexibility, stability, and reproducibility. These advantages mainly result from their material characteristics, that is, silica glass is chemically and physically stable. The article also describes the basic characteristics and recent development of arrayed waveguide grating (AWG) multiplexers/demultiplexers as a device application. Since AWGs offer the advantages of low-loss, high-output port counts and mass producibility, they have played a pivotal role in the construction of flexible, large-capacity WDM networks.

Hot-melt adhesives facilitate fast production processes because the adhesives set simply by cooling. Formulations contain polymers to provide strength and hot tack (resistance to separation while adhesive is hot), and tackifiers and/or oils to dilute the polymer entanglement network, adjust the glass-transition temperature, lower the viscosity, and improve wet-out (molecular contact of the adhesive with the substrate over the entire bonding area). Some adhesives also contain waxes to speed setting, lower viscosity, and improve heat resistance. Obtaining adequate strength and heat resistance from nonreactive hot melts requires that some component of the hot melt separate out into a dispersed but interconnected hard-phase network upon cooling. The hard phases are commonly either glassy styrene domains (for adhesives based on styrenic block copolymers) or organic crystallites (for adhesives based on waxes, olefinic copolymers, or ethylene copolymers). This article will describe first the material properties relevant to the processing and performance of hot-melt adhesives, then the chemistry and function of the specific raw materials used in hot melts, and will conclude with illustrative application examples and corresponding formulations.

The following article is an edited transcript of a talk presented in Symposium X—Frontiers of Materials Research at the 2002 Materials Research Society Fall Meeting in Boston on December 2, 2002. From Bessemer steel used on the first motorized bicycle in 1871 to sintered aluminum ceramic composites and TiN thin-film coatings used on standard production machines today, motorcycles have been at the forefront of the use of high-performance materials. Thanks to developments in materials technology, relatively inexpensive mass-produced motorcycles are now capable of achieving speeds of >190 mph.

Oxide-based ceramic materials are rapidly proving to have exciting potential for application as hard coatings. The most commonly known oxide material is silica, with a well-known variety of polytypes. Many other oxides, especially those involving metals, are now also proving to be important for a variety of applications where, because of the chemical role played by metal d electrons, large oxygen coordinations can be sustained. Properties of a variety of oxides—from silica to metal-based oxides—are discussed, and the role of predictive computer modeling is shown to be valuable in guiding the search for potentially new superhard oxides.

Protein biochips have recently gained a lot of attention as bioanalytical tools in the life sciences. The creation of such biochips has been made possible by the integration of scientific approaches and methodologies in microfabrication, organic interface chemistry, protein engineering, detection physics, and—last but not least—advances in microarrays and microfluidic dispensing technologies. This article reviews some of the current drop-on-demand technologies developed for printing biomolecular arrays, with an emphasis on proteins and the technical challenges associated with them.

Cellular ceramics are a class of high-porosity materials that are used or are being considered for a wide range of technological applications. A critical aspect of this development is the materials science approach required to understand the relationships between the properties of these materials and their structure. Of particular interest are the parameters that control mechanical reliability, as ceramic materials are usually brittle. In addition, it is critical to understand the way in which processing methods can influence the cellular structure. This article emphasizes one particular group of cellular ceramics known as ceramic foams. Understanding these materials involves various interdisciplinary scientific challenges in characterizing structure, developing micromechanical models, experimentally measuring properties, developing new processing approaches, and optimizing performance.

High-throughput synthesis and characterization techniques have been effective in discovering new materials and performing rapid mapping of phase diagrams. The application of the combinatorial strategy to explore doped transition-metal oxides has led to the discovery of a transparent room-temperature ferromagnetic oxide in Co-doped anatase TiO2. The discovery has triggered a wave of studies into other metal oxide systems in pursuit of diluted magnetic semiconductors. In this article, we describe recent combinatorial studies of magnetic transition-metal oxides, germanium-based magnetic semiconductors, and Heusler alloys.

Surface engineering is now a key materials technology in the design of future advanced gas-turbine engines. This article focuses on coating systems for hot-gas-path components, which can vary from low-cost aluminide diffusion coatings to the more exotic, and therefore expensive, thermal-barrier coatings. Available coating systems and their relative benefits are reviewed in terms of performance against manufacturing complexity and cost. Future trends in the design of environmental- and thermal-protection coatings are discussed, including the addition of multiple reactive elements, modified aluminide coatings, diffusion-barrier concepts, the design of “smart” corrosion-resistant coatings, and the development of structurally modified, low-thermal-conductivity thermal-barrier coatings.

Vacuum packaging of high-performance surface-micromachined uncooled microbolometer detectors and focal-plane arrays (FPAs) for infrared imaging and nonimaging applications, inertial MEMS (microelectromechanical systems) accelerometers and gyroscopes, and rf MEMS resonators is a key issue in the technology development path to low-cost, high-volume MEMS production. In this article, two approaches to vacuum packaging for MEMS will be discussed. The first is component-level vacuum packaging, a die-level approach that involves packaging individual die in a ceramic package using either a silicon or germanium lid. The second approach is wafer-level vacuum packaging, in which the vacuum-packaging process is carried out at the wafer level prior to dicing the wafer into individual die. We focus the discussion of MEMS vacuum packaging on surface-micromachined uncooled amorphous silicon infrared microbolometer detectors and FPAs for which both component-level and wafer-level vacuum packaging have found widespread application and system insertion. We first discuss the requirement for vacuum packaging of uncooled a-Si microbolometers and FPAs. Second, we discuss the details of the component-level and wafer-level vacuum-packaging approaches. Finally, we discuss the system insertion of wafer-level vacuum packaging into the Raytheon 2000AS uncooled infrared imaging camera product line that employs a wafer-level-packaged 160 × 120 pixel a-Si infrared FPA.

When exposed to radiation, the function of microelectronic devices is not only degraded by single-event phenomena but by cumulative effects. Most of the energy lost by radiation passing through semiconductors is through ionization. Buildup of charge in gate oxide layers and of interface and border traps due to ionization result in semipermanent damage to the device. These effects are known as total ionizing dose effects. A fraction of the energy of the radiation passing through semiconductors is lost to displacement of atoms from their sites in the crystal lattice structure. The buildup of displacement damage with radiation exposure causes gradual but permanent changes in device performance and limits device lifetime in a radiation environment. Displacement damage will be discussed in the context of non-ionizing energy loss.

Devices for tissue engineering comprise scaffolds with the appropriate chemistry and architecture to promote cell infiltration and colonization. The scaffold is designed with biology in mind, and thus the architecture and chemistry differ according to tissue type. In this review, we focus on scaffolds for two tissue types—bone and nervous tissue—and describe different approaches used to create them. The appropriate scaffold for a hard tissue such as bone has a high degree of interconnected macroporosity and allows the rapid invasion of cells while maintaining a rigid structure. Several approaches are described for constructing tissue-engineering scaffolds for bone. The appropriate scaffold for soft tissues like nerve fibers (e.g., axons, which conduct nerve impulses) also has a high degree of interconnected pores; however, the pores may require orientation and may be smaller. Homogeneous, high-water-content hydrogels with mechanical properties that match the soft nerve tissue are commonly used as a scaffold, and the methods used to make these are reviewed.

Semiconductor heterostructures that utilize carrier spin as a new degree of freedom offer entirely new functionality and enhanced performance over conventional devices. We describe the essential requirements for implementing this technology, focusing on the materials and interface issues relevant to electrical spin injection into a semiconductor. These are discussed and illustrated in the context of several prototype semiconductor spintronic devices, including spin-polarized light-emitting diodes and resonant tunneling structures such as the resonant interband tunneling diode.

The drive toward higher density and higher performance in integrated circuits creates a need to keep interconnects short and eliminate layers of packaging. In this article, we propose a novel, ultrahigh-density (exceeding 104 leads per cm2), compliant, wafer-level, input/output interconnection technology called “sea of leads” as a key enabling technology for future high-performance microsystems. The mechanical compliance is addressed through slippery leads (leads released from the surface) and embedded air gaps. The ability to fabricate embedded air gaps has enabled the integration of optical interconnects with high index-of-refraction mismatches between the core and cladding.