This PDF file contains the front matter associated with SPIE Proceedings Volume 8373, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

This paper introduces a label-free, electronic biomolecular sensing platform for the detection and characterization of trace amounts of biological toxins within a complex background matrix. The mechanism for signal transduction is the electrostatic coupling of molecule bond vibrations to charge transport across an insulated electrode-electrolyte interface. The current resulting from the interface charge flow has long been regarded as an experimental artifact of little interest in the development of traditional charge based biosensors like the ISFET, and has been referred to in the literature as a "leakage current". However, we demonstrate by experimental measurements and theoretical modeling that this current has a component that arises from the rate-limiting transition of a quantum mechanical electronic relaxation event, wherein the electronic tunneling process between a hydrated proton in the electrolyte and the metallic electrode is closely coupled to the bond vibrations of molecular species in the electrolyte. Different strategies to minimize the effect of quantum decoherence in the quantized exchange of energy between the molecular vibrations and electron energy will be discussed, as well as the experimental implications of such strategies. Since the mechanism for the transduction of chemical information is purely electronic and does not require labels or tags or optical transduction, the proposed platform is scalable. Furthermore, it can achieve the chemical specificity typically associated with traditional micro-array or mass spectrometry-based platforms that are used currently to analyze complex biological fluids for trace levels of toxins or pathogen markers.

Current switching speeds in CMOS technology have saturated since 2003 due to power constraints arising from the inability of line voltage to be further lowered in CMOS below about 1V. We are developing a novel switching technology based on piezoelectrically transducing the input or gate voltage into an acoustic wave which compresses a piezoresistive (PR) material forming the device channel. Under pressure the PR undergoes an insulator-to-metal transition which makes the channel conducting, turning on the device. A piezoelectric (PE) transducer material with a high piezoelectric coefficient, e.g. a domain-engineered relaxor piezoelectric, is needed to achieve low voltage operation. Suitable channel materials manifesting a pressure-induced metal-insulator transition can be found amongst rare earth chalcogenides, transition metal oxides, etc.. Mechanical requirements include a high PE/PR area ratio to step up pressure, a rigid surround material to constrain the PE and PR external boundaries normal to the strain axis, and a void space to enable free motion of the component side walls. Using static mechanical modeling and dynamic electroacoustic simulations, we optimize device structure and materials and predict performance. The device, termed a PiezoElectronic Transistor (PET) can be used to build complete logic circuits including inverters, flip-flops, and gates. This "Piezotronic" logic is predicted to have a combination of low power and high speed operation.

Micro/nanoscale resonator oscillators offer size, weight, and cost advantages to traditional quartz crystal oscillators. However, they typically cannot produce equivalent performance. Analyses and simulation are used to determine performance thresholds necessary for application of these devices in communication and navigation radios. Micro/nanoscale resonator oscillators have been created which use nonlinearities to improve their phase noise. These devices were used in actual radios to verify analyses and simulation. Measured results have shown radio performance equivalent to a 236 km communication range increase. A microscale oscillator was successfully used as a frequency reference in a navigation radio to acquire and track GPS.

Stable local oscillators with low phase noise are extremely important elements in high performance military communication and navigation systems. We present the development of compact UHF-band frequency sources capable of maintaining low phase noise under high accelerations or vibrations and over a wide temperature range for handheld portable systems. We also explored nonlinearity in MEMS resonators and attempted to use nonlinear dynamics to enhance phase noise performance. Using the quartz MEMS technology, we have thus far demonstrated a 645 MHz Pierce oscillator with -113 dBc/Hz phase noise at 1 kHz offset with acceleration sensitivity of 5x10^-10/g. The controlled oscillation of a nonlinear Duffing resonator in a closed-loop system with improved phase noise is described.

Topological surface states are a new class of electronic states with novel properties. In this talk, I will review the properties of these novel quantum states and highlight some of their key properties that may be harnessed for potential applications. In particular, I will describe efforts in which combination of voltage controlled magnetism and topological surface states may be used to realize a novel low voltage transistor.

The emerging discipline of coherent-feedback quantum control provides core concepts and methods for nanopho- tonic circuit theory, which can be assimilated within modern approaches to computer-aided design. Current research in this area includes the development of software tools to enable a schematic capture workflow for compilation and analysis of quantum stochastic models for nanophotonic circuits, exploration of elementary coherent-feedback circuit motifs, and laboratory demonstrations of quantum nonlinear photonic devices.

Topological insulators are new states of quantum matter with novel electronic properties. Inside two dimensional magnetic topological insulators, electrical currents are confined at the edge of the sample, and counter propagating directions are spatially separated like automobiles on a highway. Local electrical resistivity is completely eliminated in such topological insulators, and only terminal or contact resistances remain. We show that this principle can be used to construct chiral interconnects on computing devices where the total resistance is independent of the length, thus eliminating a major obstacle of the electronics technology.

This work presents the development of high frequency mechanical oscillators based on non-linear laterally vibrating aluminum nitride (AlN) piezoelectric resonators. Our efforts are focused on harnessing non-linear dynamics in resonant mechanical devices to devise frequency sources operating around 1 GHz and capable of outperforming state-of-the-art oscillators in terms of phase noise and size. To this extent, we have identified the thermal and mechanical origin of non-linearities in micro and nanomechanical AlN resonators and developed a theory that describes the optimal operating point for non-linear oscillators. Based on these considerations, we have devised 1 GHz oscillators that exhibit phase noise of < -90 dBc/Hz at 1 kHz offset and < -160 dBc/Hz at 10 MHz offset. In order to attain thermally stable oscillators showing few ppm shifts from - 40 to + 85 °C, we have implemented an embedded ovenization technique that consumes only few mW of power. By means of simple microfabrication techniques, we have included a serpentine heater in the body of the resonator and exploited it to heat it and monitor its temperature without degrading its electromechanical performance. The ovenized devices have resulted in high frequency stability with just few ppm of shift over the temperature range of interest. Finally, few of these oscillators were tested according to military standards for acceleration sensitivity and exhibited a frequency sensitivity lower than 30 ppb/G. These ultra stable oscillators with low jitter and phase noise will ultimately benefit military as well as commercial communication systems.

Topological insulators (TI) have emerged as a new class of quantum materials with many novel and unusual properties. In this article, we will give a brief review of the key electronic properties of topological insulators, including the signatures for the unusual electronic transport properties of their characteristic topological surface states (TSS). We will then discuss how these novel properties and physics may be utilized for TI-based energy efficient devices, such as lowpower- consumption electronics and high performance thermo-electrics. Furthermore, going beyond conventional singleparticle, charge-based transport, to utilize coherent many-body coherent ground states such as excitonic condensates (EC), new and intriguing functionalities previously unexplored in electronic and energy devices may be realized with the potential to dramatically improve the energy efficiency.

We present an information transduction architecture that utilizes coherent interconversion between photons, magnons and electric charge carriers. The materials we use are low loss magneto-optic yttrium iron garnet (YIG). This device platform enables high fidelity communication devices, as well as small size microwave signal processing devices for Radar and defense related applications. Specific examples given here are widely tunable microwave oscillators, variable low loss delay lines, and high Q delay line oscillators.

We review the physics of photon-phonon coupling in guided wave systems, and discuss new opportunities for information transduction aorded by nanoscale connement of light and phonons within a novel class of optome- chanical waveguide systems. We present a fundamental analysis of optical forces generated through nanoscale light-matter interactions, and use these insights to develop new approaches for broadband signal processing via optomechanics. Recent experimental results will also be discussed.

Identification of the presence of radioactive materials is important for both defense and environmental concerns. Nanoscience may enable improved understanding of energy storage or transfer processes that can be exploited for indicators. For example, nanoscale materials that emit spectral signatures in the presence of ionizing radiation or nuclear particles, when incorporated in other widely used materials or objects, would assist in locating and securing radiological or nuclear materials.

We exploit the dependence of the electrical conductivity of graphene on a local electric field, which can be abruptly changed by charge carriers generated by ionizing radiation in an absorber material, to develop novel highperformance radiation sensors for detection of photons and other kinds of ionizing radiation. This new detection concept is implemented by configuring graphene as a field effect transistor (FET) on a radiation-absorbing undoped semiconductor substrate and applying a gate voltage across the sensor to drift charge carriers created by incident photons to the neighborhood of graphene, which gives rise to local electric field perturbations that change graphene resistance. Promising results have been obtained with CVD graphene FETs fabricated on various semiconductor substrates that have different bandgaps and stopping powers to address different application regimes. In particular, graphene FETs made on SiC have exhibited a ~200% increase in graphene resistance at a gate voltage of 50 V when exposed to room light at room temperature. Systematic studies have proven that the observed response is a field effect.

Silicon diodes with large aspect ratio microstructures backfilled with ⁶LiF show a dramatic increase in neutron detection efficiency beyond that of conventional thin-film coated planar devices. Described in this work are advancements in the technology with increased microstructure depths and detector stacking methods that work to increase thermal-neutron detection efficiency. An individual 4-cm² MSND was fabricated. A stacked 4-cm² MSND was fabricated by coupling two detectors back-to-back, along with counting electronics, into a single detector. The individual MSND delivered 16% intrinsic thermal-neutron detection efficiency and the stacked MSND delivered 32% intrinsic thermal-neutron detection efficiency. The intrinsic thermal-neutron detection efficiency depends strongly upon the geometry, size, and depth of the silicon microstructures. This work is part of on-going research to develop solid-state semiconductor neutron detectors with high neutron detection efficiencies.

Current state-of-the-art nanotechnology offers multiple benefits for radiation sensing applications. These include the ability to incorporate nano-sized radiation indicators into widely used materials such as paint, corrosion-resistant coatings, and ceramics to create nano-composite materials that can be widely used in everyday life. Additionally, nanotechnology may lead to the development of ultra-low power, flexible detection systems that can be embedded in clothing or other systems. Graphene, a single layer of graphite, exhibits exceptional electronic and structural properties, and is being investigated for high-frequency devices and sensors. Previous work indicates that graphene-oxide (GO) - a derivative of graphene - exhibits luminescent properties that can be tailored based on chemistry; however, exploration of graphene-oxide's ability to provide a sufficient change in luminescent properties when exposed to gamma or neutron radiation has not been carried out. We investigate the mechanisms of radiation-induced chemical modifications and radiation damage induced shifts in luminescence in graphene-oxide materials to provide a fundamental foundation for further development of radiation sensitive detection architectures. Additionally, we investigate the integration of hexagonal boron nitride (hBN) with graphene-based devices to evaluate radiation induced conductivity in nanoscale devices. Importantly, we demonstrate the sensitivity of graphene transport properties to the presence of alpha particles, and discuss the successful integration of hBN with large area graphene electrodes as a means to provide the foundation for large-area nanoscale radiation sensors.

The use of light emitting nanoparticles in polymer and glass matrices was studied for the detection of radiation. These nanocomposite scintillators were produced by various approaches including quantum dot/polymer, fluoride nanophosphor/epoxy and halide nanophosphor containing glass-ceramic composites. The synthesis and characterization of these nanoparticles as well as their incorporation into composites is discussed. Further, the application of these composites for radiation detection and spectroscopy is described.

Atomic Force Microscopy (AFM) and infrared (IR) spectroscopy have been combined in a single instrument capable of producing sub-micron spatial resolution IR spectra and images. This new capability enables the sprectroscopic characterization of microdomain-forming polymers at levels not previously possible. Films of poly(3-hydroxybutyrate-co-3-hydroxyheanoate) were solution cast on ZnSe prisms. Dramitic differences in the IR spectra are observed in the 1200-1300 cm^-1 range as a funstion of position on a spatial scale of less than one micron. This spectral region is particularly sensitive to the polymer crystallinity, enabling the identification of crystalline and amorphous domains within a single spherulite of this polymer.

The goal of our project is to develop a new therapy for childhood malignancies using nanoformulated siRNA targeting Mxd3, a molecule in the Sonic Hedgehog signaling pathway, which we believe is important for cell survival. We plan to use cancer-specific ligands and superparamagnetic iron oxide nanoparticles (SPIO NPs) to carry siRNA. This delivery system will be tested in mouse xenograft models that we developed with primary cancer tissues. Our current focus is acute lymphoblastic leukemia (ALL), the most common cancer in children. We report our progress to date.

Solid-state nanopore sensors are promising devices for single DNA molecule detection and sequencing. This paper presents a review of our work on solid-state nanopores performed over the last decade. In particular, here we discuss atomic-layer-deposited (ALD)-based, graphene-based, and functionalized solid state nanopores.

Rapid and cost-effective DNA sequencing is a pivotal prerequisite for the genomics era. Many of the recent advances in forensics, medicine, agriculture, taxonomy, and drug discovery have paralleled critical advances in DNA sequencing technology. Nanopore modalities for DNA sequencing have recently surfaced including the electrical interrogation of protein ion channels and/or solid-state nanopores during translocation of DNA. However to date, most of this work has met with mixed success. In this work, we present a unique nanofabrication strategy that realizes an artificial nanopore articulated with carbon electrodes to sense the current modulations during the transport of DNA through the nanopore. This embodiment overcomes most of the technical difficulties inherent in other artificial nanopore embodiments and present a versatile platform for the testing of DNA single nucleotide detection. Characterization of the device using gold nanoparticles, silica nanoparticles, lambda dsDNA and 16-mer ssDNA are presented. Although single molecule DNA sequencing is still not demonstrated, the device shows a path towards this goal.

Adaptive Optics (AO) is an ensemble of techniques that aims at the remedial of the deleterious effects that the Earth's turbulent atmosphere induces on both imagery and signal gathering in real time. It has been over four decades since the first AO system was developed and tested. During this time important technological advances have changed profoundly the way that we think and develop AO systems. The use of Micro-Electro-Mechanical-Systems (MEMS) devices and Liquid Crystal Devices (LCD) has revolutionized these technologies making possible to go from very expensive, very large and power consuming systems to very compact and inexpensive systems. These changes have rendered AO systems useful and applicable in other fields ranging from medical imaging to industry. In this paper we will review the research efforts at the Naval research Laboratory (NRL) to develop AO systems based on both MEMs and LCD in order to produce more compact and light weight AO systems.

The Naval Research Laboratory and Sandia National Laboratories have been actively researching the use of carbon fiber reinforced polymer material as optical elements in many optical systems. Active optical elements can be used to build an optical system capable of changing is optical zoom. We have developed a two-element optical system that uses a large diameter, thin-shelled carbon fiber reinforced polymer mirror, actuated with micro-positioning motors, and a high actuator density micro-electro-mechanical deformable mirror. Combined with a Shack-Hartmann wavefront sensor, we have optimized this actuated carbon fiber reinforced polymer deformable mirror's surface for use with a forthcoming reflective adaptive optical zoom system. In this paper, we present the preliminary results of the carbon fiber reinforced polymer deformable mirror's surface quality and the development of the actuation of it.

Micro-electro-mechanical systems (MEMS) deformable mirrors are known for their ability to correct optical aberrations, particularly when the wavefront is expanded via Zernike polynomials. This capability is combined with adaptive optical zoom to enable diffraction limited performance over broad spectral and zoom ranges. Adaptive optical zoom (AOZ) alters system magnification via variable focal length elements instead of axial translation found in traditional zoom designs. AOZ systems are simulated using an efficient approach to optical design, in which existing theories for telescope objective design and third-order aberration determination are modified to accommodate the additional degrees of freedom found with AOZ. An AOZ system with a 2.7× zoom ratio and 100mm entrance pupil diameter is presented to demonstrate the validity and capability of the theory.

We describe the construction and application of innovative deformable mirrors for adaptive optics (AO) being developed at the University of Arizona's Center for Astronomical Adaptive Optics. The mirrors are up to 1 m in diameter, with high actuator stroke, and are optically powered. Scientific motivations for the work include the detection of earthlike planets around other nearby stars, as well as non-astronomical applications such as directed energy and horizontal imaging for defense and security. We describe how high resolution imaging is delivered over an unusually wide field of view by ground-layer AO. This technique employs multiple laser guide stars to sense the instantaneous three-dimensional distribution of atmospheric turbulence. Imaging with high signal-to-noise ratio in the thermal infrared is enabled by embedding the deformable mirror directly in the telescope. We also describe recent work to develop a new generation of these mirrors with lighter weight and improved robustness by use of replicated composite materials which shows promise for greatly reducing the cost of AO and broadening its appeal, particularly for non-astronomical applications as well as for a new generation of extremely large ground-based telescopes of 30 m diameter now under construction.

Modeling and simulating the atmosphere in a controlled environment has been a study of interest to scientists for decades. The development of new technologies allows scientists to perform this task in a more realistic and controlled environment and provides a powerful tool for the study and better understanding of the propagation of light through the atmosphere. Technologies like Free-space laser communications (FSLC) and/or studies on light propagation through the atmosphere are areas which constantly benefit from breakthroughs in the development of atmospheric turbulence simulators. In this paper we present the results of the implementation of a phase only spatial light modulator (SLM) as an atmospheric turbulence simulator at the Short-Wave Infra-Red (SWIR) regime and its use with a FSLC system.

An electronic nose is a sensing array designed to monitor for targeted chemical species or mixtures. From 1995 to 2008, an electronic nose was developed at the Jet Propulsion Laboratory (JPL) to monitor the environment in human occupied spacecraft for the sudden release, such as leaks or spills, of targeted chemical species. The JPL ENose was taken through three generations of device, from basic exploratory research into polymer-carbon composite chemiresistive sensors to a fully operating instrument which was demonstrated on the International Space Station for several months. The Third Generation JPL ENose ran continuously in the U.S. Lab on the International Space Station to monitor for sudden releases of a targeted group of chemical species. It is capable of detecting, identifying and quantifying targeted species in the parts-per-million range in air, and of operating at a range of temperatures, humidities and pressures.

Electric current output or scintillation light from solid-state inorganic materials under ionizing radiation is very useful for nuclear and radiation detection. Direct electric current measurements in semiconductors or ionic crystals provide high resolution spectroscopy and imaging capability even though there are scalability and cost issues. In contrast, inorganic scintillation materials utilizing photons generated by incident radiation have been developed for many decades and provide better scalability and lower cost. Ceramic materials offer compelling advantages including large size, mechanical strength, and homogeneity. In this work, we review current status of advanced radiation detection materials and introduce our efforts in the development of ceramic scintillator materials, mainly for gamma ray detection.

Combustion produced common air pollutant, NOx associates with greenhouse effects. Its high temperature detection is essential for protection of nature. Component-integration capable high-temperature sensors enable the control of combustion products. The requirements are quantitative detection of total NO_x and high selectivity at temperatures above 500°C. This study reports various approaches to detect NO and NO₂ selectively under lean and humid conditions at temperatures from 300°C to 800°C. All tested electrochemical sensors were fabricated in planar design to enable componentintegration. We suggest first an impedance-metric gas sensor for total NOx-detection consisting of NiO- or NiCr₂O₄-SE and PYSZ-electrolyte. The electrolyte-layer is about 200μm thickness and constructed of quasi-single crystalline columns. The sensing-electrode (SE) is magnetron sputtered thin-layers of NiO or NiCr₂O₄. Sensor sensitivity for detection of total NOx has been measured by applying impedance analysis. The cross-sensitivity to other emission gases such as CO, CO₂, CH₄ and oxygen (5 vol.%) has been determined under 0-1000ppm NO. Sensor maintains its high sensitivity at temperatures up to 550°C and 600°C, depending on the sensing-electrode. NiO-SE yields better selectivity to NO in the presence of oxygen and have shorter response times comparing to NiCr₂O₄-SE. For higher temperature NO₂-sensing capability, a resistive DC-sensor having Al-doped TiO₂-sensing layers has been employed. Sensor-sensitivity towards NO2 and cross-sensitivity to CO has been determined in the presence of H₂O at temperatures 600°C and 800°C. NO₂ concentrations varying from 25 to 100ppm and CO concentrations from 25 to 75ppm can be detected. By nano-tubular structuring of TiO₂, NO₂ sensitivity of the sensor was increased.

Absorption of the light by a solar cell can be improved significantly by light trapping structures formed on the front surface of the device. In particular, thin crystalline and amorphous solar cells are expected to benefit from the improved light absorption in a region closer to the surface of the cell. Recently, we have shown that vertically aligned silicon (Si) nanowires formed on flat (100) Si wafer surface by metal assisted etching can effectively be used for this purpose. In this paper we present demonstration of nanowire application to industrial size solar cell system and a comparison between flat and pyramid textured Si wafers. Standard procedures were followed to fabricate solar cells with and without Si nanowire process on mirror like and pyramid textured Si wafers. The dependence of the solar cell parameters on the process parameters was studied systematically. Reflection spectra showed successful light trapping behavior on the surface of the cells. In all samples, we have obtained excellent current-voltage (I-V) characteristics with high fill factors. However, the efficiency of the cells was found to decrease with the etch duration. This can be attributed to the increased recombination along the nanowires or increased surface area due to the roughening of the surface after etching process.

Recently nanostructure materials have emerged as a building block for constructing next generation of photovoltaic devices. Nanowire based semiconductor solar cells, among other candidates, have shown potential to produce high efficiency. In a radial pn junction light absorption and carrier collection can be decoupled. Also nanowires can increase choice of materials one can use to fabricate high efficiency tandem solar cells by relaxing the lattice-match constraint. Here we report synthesis of vertical III-V semiconducting nanowire arrays using Selective-Area Metal Organic Chemical Vapor Deposition (SA-MOCVD) technique, which can find application in various optoelectronic devices. We also demonstrate nanosphere lithography (NSL) patterning techniques to obtain ordered pattern for SAMOCVD. Reflection spectrum of nanowires array made by this technique shows excellent light absorption performance without additional anti-reflection coating layer. Thus, we show that highly ordered nanowire structure is 'not needed' to maximize the absorption in vertical nanowire array. Our scalable approach for synthesis of vertical semiconducting nanowire can have application in high throughput and low cost optoelectronic devices including photovoltaic devices.

Micro scale and nano scale technology developments have the potential to revolutionize smart and small systems. The application of systems engineering methodologies that integrate standalone, small-scale technologies and interface them with macro technologies to build useful systems is critical to realizing the potential of these technologies. This paper covers the expanding knowledge base on systems engineering principles for micro and nano technology integration starting with a discussion of the drivers for applying a systems approach. Technology development on the micro and nano scale has transition from laboratory curiosity to the realization of products in the health, automotive, aerospace, communication, and numerous other arenas. This paper focuses on the maturity (or lack thereof) of the field of nanosystems which is emerging in a third generation having transitioned from completing active structures to creating systems. The emphasis of applying a systems approach focuses on successful technology development based on the lack of maturity of current nano scale systems. Therefore the discussion includes details relating to enabling roles such as product systems engineering and technology development. Classical roles such as acquisition systems engineering are not covered. The results are also targeted towards small-scale technology developers who need to take into account systems engineering processes such as requirements definition, verification, and validation interface management and risk management in the concept phase of technology development to maximize the likelihood of success, cost effective micro and nano technology to increase the capability of emerging deployed systems and long-term growth and profits.

Current solar power systems using crystalline silicon wafers, thin film semiconductors (i.e., CdTe, amorphous Si, CIGS, etc.), or concentrated photovoltaics have yet to achieve the cost reductions needed to make solar power competitive with current grid power costs. To overcome this cost challenge, we are pursuing a new approach to solar power that utilizes micro-scale solar cells (5 to 20 μm thick and 100 to 500 μm across). These micro-scale PV cells allow beneficial scaling effects that are manifested at the cell, module, and system level. Examples of these benefits include improved cell performance, better thermal management, new module form-factors, improved robustness to partial shading, and many others. To create micro-scale PV cells we are using technologies from the MEMS, IC, LED, and other micro and nanosystem industries. To date, we have demonstrated fully back-contacted crystalline silicon (c-Si), GaAs, and InGaP microscale solar cells. We have demonstrated these cells individually (c-Si, GaAs), in dual junction arrangements (GaAs, InGaP), and in a triple junction cell (c-Si, GaAs, InGaP) using 3D integration techniques. We anticipate two key systems resulting from this work. The first system is a high-efficiency, flexible PV module that can achieve greater than 20% conversion efficiency and bend radii of a few millimeters (both parameters greatly exceeding what currently available flexible PV can achieve). The second system is a utility/commercial scale PV system that cost models indicate should be able to achieve energy costs of less than $0.10/kWh in most locations.

Nanomaterials have provided some of the greatest leaps in technology over the past twenty years, but their relatively early stage of maturity presents challenges for their incorporation into engineered systems. Perhaps even more challenging is the fact that the underlying physics at the nanoscale often run counter to our physical intuition. The current state of nanotechnology today includes nanoscale materials and devices developed to function as components of systems, as well as theoretical visions for "nanosystems," which are systems in which all components are based on nanotechnology. Although examples will be given to show that nanomaterials have indeed matured into applications in medical, space, and military systems, no complete nanosystem has yet been realized. This discussion will therefore focus on systems in which nanotechnology plays a central role. Using self-assembled magnetic artificial cilia as an example, we will discuss how systems engineering concepts apply to nanotechnology.

Operating in dynamic lighting conditions and in greatly varying backgrounds is challenging. Current paints and state-ofthe- art passive adaptive coatings (e.g. photochromics) are not suitable for multi- environment situations. A semi-active, low power, skin is needed that can adapt its reflective properties based on the background environment to minimize contrast through the development and incorporation of suitable pigment materials. Electrofluidic skins are a reflective display technology for electronic ink and paper applications. The technology is similar to that in E Ink but makes use of MEMS based microfluidic structures, instead of simple black and white ink microcapsules dispersed in clear oil. Electrofluidic skin's low power operation and fast switching speeds (~20 ms) are an improvement over current state-ofthe- art contrast management technologies. We report on a microfluidic display which utilizes diffuse pigment dispersion inks to change the contrast of the underlying substrate from 5.8% to 100%. Voltage is applied and an electromechanical pressure is used to pull a pigment dispersion based ink from a hydrophobic coated reservoir into a hydrophobic coated surface channel. When no voltage is applied, the Young-Laplace pressure pushes the pigment dispersion ink back down into the reservoir. This allows the pixel to switch from the on and off state by balancing the two pressures. Taking a systems engineering approach from the beginning of development has enabled the technology to be integrated into larger systems.

The world's dominant IC material, silicon, cannot do everything we want a semiconductor material to do. However, for this discussion, the fact that Si wafers are of high quality, large and cheap is of great interest. This is important for at least two reasons. First, nearly all of the electronic and photonic compound semiconductor devices that comprise the current $20 billion per year market are fabricated on substrates that are either very expensive or non-optimal for the epitaxy required to realize the device or an IC of interest. A second reason is the integration of new functionality to current Si technology. Clearly, if many of the current photonic applications already realized in current compound semiconductor technology could be integrated into Si technology, some of the herculean efforts to continue following Moore's Law (including trying to do it via nanotechnology) could be mitigated. This presentation examines some of the basic materials science issues involved with heterogeneous integration of semiconductor materials. These include those applications in which the active device region requires a high degree of crystal perfection and those that do not. Epitaxy issues at the hetero-interface, heterovalent versus homovalent epigrowth, and dislocation dynamics are presented. Notable historical examples are summarized, followed by examples of current successful approaches including the materials science concepts used to achieve the results. A list is made of some challenges that need to be solved in order to continue making future progress.

Optical nanoantennas are analogs of radio-frequency antennas for light. In this work, we first describe how the optical nanoantennas are similar to their RF counterparts in some ways and differ from them in some other aspects. We also focus on the use of split ring resonator based metamaterials, which are essentially optical antennas with a C-shaped compact geometry. We also discuss how they can be used in sensing applications for the infrared detection of a monolayer of molecules with zeptomoles per resonator sensitivity.

We review our recent progress on computational lensfree on-chip microscopy and tomography techniques for biomedical imaging and telemedicine applications.

Unconventional approaches to exploit established materials in photovoltaics can create novel engineering opportunities, device functionalities, and cost structures, each of which can have significant values in different technological applications. Here, I present an overview of materials and integration strategies that involve a large collection of monocrystalline silicon in micro and nanostructured forms that are derived from wafer-based source materials. Printinglike assembly techniques offered a practical means to manipulate ultrathin, micro/nanoscale building blocks in a massively parallel, cost-effective manner, thereby enabling device- and module-level integration on various classes of foreign substrates with advantages in areal coverages, formats, and costs that have been difficult in conventional crystalline silicon photovoltaics.

This paper discusses the systematic experimental and vehicle design/development studies conducted at the University of Maryland which culminated in the development of the first flying Cyclocopter in the history. Cyclocopter is a novel Vertical Take-Off and Landing (VTOL) aircraft, which utilizes cycloidalrotors (cyclorotors), a revolutionary horizontal axis propulsion concept, that has many advantages such as higher aerodynamic efficiency, maneuverability and high-speed forward flight capability when compared to a conventional helicopter rotor. The experimental studies included a detailed parametric study to understand the effect of rotor geometry and blade kinematics on cyclorotor hover performance. Based on the experimental results, higher blade pitch angles were found to improve thrust and increase the power loading (thrust per unit power) of the cyclorotor. Asymmetric pitching with higher pitch angle at the top than at the bottom produced better power loading. The chordwise optimum pitching axis location was observed to be around 25-35% of the blade chord. Because of the flow curvature effects, the cycloidal rotor performance was a strong function of the chord/radius ratio. The optimum chord/radius ratios were extremely high, around 0.5-0.8, depending on the blade pitching amplitude. A flow field investigation was also conducted using Particle Image Velocimetry (PIV) to unravel the physics behind thrust production of a cyclorotor. PIV studies indicated evidence of a stall delay as well as possible increases in lift on the blades from the presence of a leading edge vortex. The goal of all these studies was to understand and optimize the performance of a micro-scale cyclorotor so that it could be used in a flying vehicle. An optimized cyclorotor was used to develop a 200 gram cyclocopter capable of autonomous stable hover using an onboard feedback controller.

Millimeter-scale robotic systems based on highly integrated microelectronics and micro-electromechanical systems (MEMS) could offer unique benefits and attributes for small-scale autonomous systems. This extreme scale for robotics will naturally constrain the realizable system capabilities significantly. This paper assesses the feasibility of developing such systems by defining the fundamental design trade spaces between component design variables and system level performance parameters. This permits the development of mobility enabling component technologies within a system relevant context. Feasible ranges of system mass, required aerodynamic power, available battery power, load supported power, flight endurance, and required leg load bearing capability are presented for millimeter-scale platforms. The analysis illustrates the feasibility of developing both flight capable and ground mobile millimeter-scale autonomous systems while highlighting the significant challenges that must be overcome to realize their potential.

A 12 gram fly-inspired flapping wing micro air vehicle was stabilized in the yaw degree of freedom using insectbased wing kinematic for lift generation and control actuation. The characteristic parameters of biological insect flapping flight are described. The integration of this parametric understanding of biological flight into the design of the vehicle is also discussed.

Palm sized legged robots show promise for military and civilian applications, including exploration of hazardous or difficult to reach places, search and rescue, espionage, and battlefield reconnaissance. However, they also face many technical obstacles, including- but not limited to- actuator performance, weight constraints, processing power, and power density. This paper presents an overview of several robots from the Biomimetic Millisystems Laboratory at UC Berkeley, including the OctoRoACH, a steerable, running legged robot capable of basic navigation and equipped with a camera and active tail; CLASH, a dynamic climbing robot; and BOLT, a hybrid crawling and flying robot. The paper also discusses, and presents some preliminary solutions to, the technical obstacles listed above plus issues such as robustness to unstructured environments, limited sensing and communication bandwidths, and system integration.

The challenges for successful flight of insect-scale micro air vehicles encompass basic questions of fabrication, design, propulsion, actuation, control, and power - topics that have in general been answered for larger aircraft. When developing a flying robot on the scale of flies and bees, all hardware must be developed from scratch as there are no "off-the-shelf" sensors, actuators, or microcontrollers that can satisfy the extreme mass and power limitations imposed by such vehicles. Similar challenges exist for fabrication and assembly of the structural and aeromechanical components of insect-scale micro air vehicles that neither macro-scale techniques nor MEMS can adequately solve. With these challenges in mind, this paper presents progress in the essential technologies for micro-scale flapping-wing robots.

Small autonomous aerial systems require the ability to detect roll, pitch, and yaw to enable stable flight. Existing inertial measurement units (IMUs) are incapable of accurately measuring roll-pitch-yaw within the size, weight, and power requirements of at-scale insect-inspired aerial autonomous systems. To overcome this, we have designed novel IMUs based on the biological haltere system in a microelectromechanical system (MEMS). MEMS haltere sensors were successfully simulated, designed, and fabricated with a control scheme that enables simple, straightforward decoupling of the signals. Passive mechanical logic was designed to facilitate the decoupling of the forces acting on the sensor. The control scheme was developed that efficiently and accurately decouples the three component parts from the haltere sensors. Individual, coupled, and arrayed halteres were fabricated. A series of static electrical tests and dynamic device tests were conducted, in addition to in-situ bend tests, to validate the simulation results, and these, taken as a whole, indicate that the MEMS haltere sensors will be inherently sensitive to the Coriolis forces caused by changes in angular rate. The successful fabrication of a micro-angular rate sensor represents a substantial breakthrough and is an enabling technology for a number of Army applications, including micro air vehicles (MAVs).

We seek to harness microelectromechanical systems (MEMS) technologies to build biomimetic devices for low-power, high-performance, robust sensors and actuators on micro-autonomous robot platforms. Hair is used abundantly in nature for a variety of functions including balance and inertial sensing, flow sensing and aerodynamic (air foil) control, tactile and touch sensing, insulation and temperature control, particle filtering, and gas/chemical sensing. Biological hairs, which are typically characterized by large surface/volume ratios and mechanical amplification of movement, can be distributed in large numbers over large areas providing unprecedented sensitivity, redundancy, and stability (robustness). Local neural transduction allows for space- and power-efficient signal processing. Moreover by varying the hair structure and transduction mechanism, the basic hair form can be used for a wide diversity of functions. In this paper, by exploiting a novel wafer-level, bubble-free liquid encapsulation technology, we make arrays of micro-hydraulic cells capable of electrostatic actuation and hydraulic amplification, which enables high force/high deflection actuation and extremely sensitive detection (sensing) at low power. By attachment of cilia (hair) to the micro-hydraulic cell, air flow sensors with excellent sensitivity (< few cm/s) and dynamic range (> 10 m/s) have been built. A second-generation design has significantly reduced the sensor response time while maintaining sensitivity of about 2 cm/s and dynamic range of more than 15 m/s. These sensors can be used for dynamic flight control of flying robots or for situational awareness in surveillance applications. The core biomimetic technologies developed are applicable to a broad range of sensors and actuators.

This paper reports on a novel technology for low-noise un-cooled detection of infrared (IR) radiation using a combination of piezoelectric, pyroelectric, electrostrictive, and resonant effects. The architecture consists of a parallel array of high-Q gallium nitride (GaN) micro-mechanical resonators coated with an IR absorbing nanocomposite. The nanocomposite absorber converts the IR energy into heat with high efficiency. The generated heat causes a shift in frequency characteristics of the GaN resonators because of pyroelectric effect. IR detection is achieved by sensing the shift in the resonance frequency and amplitude of the exposed GaN resonator as compared to a reference resonator that is included in the array. This architecture offers improved signal to noise ratio compared with conventional pyroelectric detectors as the resonant effect reduces the background noise and improves sensitivity, enabling IR detection with NEDTs below 5 mK at room temperature. GaN is chosen as the resonant material as it possesses high pyroelectric, electrostrictive, and piezoelectric coefficients and can be grown on silicon substrates for low-cost batch fabrication. Measured results of a GaN IR detector prototype and a thin-film nanocomposite IR absorber are presented in this paper.

Sensors for autonomous small robotic platforms must be low mass, compact size and low power due to the limited space. For such applications, as the dimensions of the structures shrink, standard machining methods are not suitable because of low fabrication tolerances and high cost in assembly. Commonly, the structures show a high degree of fabrication complexity due to error in alignment, air gaps between conductive parts, poor metal contact, inaccuracy in patterning because of non-contact lithography, complex assemblies of various parts, and high number of steps needed for construction. However, micromachining offers high fabrication precision, provides easy fabrication and integration with active devices and hence is suitable for manufacturing high MMW and submillimeter-wave frequency structures. A radar design compatible with micromachining process is developed to fabricate a Y-band high resolution radar structure with a slot-fed patch array antenna. A multi-step silicon DRIE process is developed for the fabrication of the waveguide structure while the slots are suspended on a thin oxide/nitride/oxide membrane to form the top cover of the waveguide trenches and the patch elements are suspended on a thin Parylene membrane. Gold thermocompression bonding and Parylene bonding are used to assemble different parts of the antenna. These processes result in a compact (4.5 cm × 3.5 cm × 1.5 mm) and light-weight (5 g) radar.

Gas analysis systems having small size, low power, and high selectivity are badly needed for defense (detection of explosives and chemical warfare agents), homeland security, health care, and environmental applications. This paper presents a palm-size gas chromatography system having analysis times of 5-50sec, detection limits less than 1ppb, and an average power dissipation less than one watt. It uses no consumables. The three-chip fluidic system consists of a preconcentrator, a 25cm-3m separation column, and a chemi-resistive detector and is supported by a microcomputer and circuitry for programmable temperature control. The entire system, including the mini-pump and battery, occupies less than 200cc and is configured for use on autonomous robotic vehicles.

Over the past two decades, nanotechnology has offered the promise of revolutionary performance improvements over existing armor materials. During that time there was substantial effort and resources put into developing the material technology and supporting theories, with only limited emphasis placed on understanding the ballistic event, mechanisms that drive armor performance, and the dependent nature of the threat. As a result, this large investment in nanotechnology for armor has not produced improved performance on the ballistics testing range, and armor nanotechnologies have never been fielded. No matter what the platform, armor systems have several functions that they have to perform in order to function properly. In order to defeat a threat, armor systems are designed to: deform/deflect the threat; dissipate energy; and prevent residual debris penetration. To date there is no definitive answer as to what material properties drive the system behavior of these functions at high rates in response to a specific threat, making the adaptation of nanotechnology that much harder. However, these functions are now being considered with respect to the material system and armor mechanism being utilized, and nanotechnology is beginning to be shown as an effective means of improving performance. When looking at the materials being used today, there are examples of nanotechnology making inroads into today's latest systems. Nano-particles are being used to manipulate grain boundaries in both metals and ceramics to tailor performance. Composite materials are utilizing nanotechnology to enhance basic material properties and enhance the system level behaviors to high rate events. While the anticipated revolution never occurred, nanotechnology is beginning to be utilized as an enabler in the latest armor performance improvements.

Materials for armor applications are increasingly being required to be strong and light-weight as a consequence of increasing threat levels. We focus on materials response subjected to impact loads, understanding deformation and failure mechanisms, and developing validated mechanism-based models capable of predicting materials response under high rate loading conditions. As a specific example, we will examine the dynamic behavior of nanocrystalline aluminum using atomistic simulations. The dynamic behavior of this material is discussed in terms of competing deformation mechanisms--slip and twinning. Insights from high strain rate atomistic simulations were used in developing a fundamental mechanism-based analytical model to assist in the microstructural design of advanced materials to tailor their macroscopic properties.

Using a combination of electronic structure calculations, molecular dynamics simulations, and finite-element analysis, we examine the physical mechanisms governing the performance of Kevlar®/carbon composite fibers over a variety of length scales. To begin, we use electronic structure calculations to examine the molecular structure of Kevlar polymers, and quantitatively compare the intramolecular interactions to the non-bonded intermolecular interactions. We then quantify the potential energy landscape between polymers, and fit this data to a potential function for use in molecular dynamics simulations. From molecular dynamics simulations, we calculate the stiffness and elastic modulus of pristine Kevlar fibrils and Kevlar/carbon composite fibrils. We then use a finite-element model of Kevlar fabric to examine how changes in the mechanical properties of the fibers affect the ballistic response of the fabric. These findings provide insight into how carbon fragments, which influence the nanostructure of the polymer, can enhance the ballistic performance of Kevlar fabric layers.

Memristors, usually in the form metal/metal-oxide/metal, have attracted much attention due to their potential application for non-volatile memory. Their simple structure and ease of fabrication make them good candidates for dense memory with projections of 22 terabytes per wafer. Excellent switching times of ~10 ns, memory endurance of >10⁹ cycles, and extrapolated retention times of >10 yrs have been reported. Interestingly, memristors use the migration of ions to change their resistance in response to charge flow, and can therefore measure and remember the amount of current that has flowed. This is similar to many MEMS devices in which the motion of mass is an operating principle of the device. Memristors are also similar to MEMS in the sense that they can both be resistant to radiation effects. Memristors are radiation tolerant since information is stored as a structural change and not as electronic charge. Functionally, a MEMS device's sensitivity to radiation is concomitant to the role that the dielectric layers play in the function of the device. This is due to radiation-induced trapped charge in the dielectrics which can alter device performance and in extreme cases cause failure. Although different material systems have been investigated for memristors, SnO₂ has received little attention even though it demonstrates excellent electronic properties and a high resistance to displacement damage from radiation due to a large Frenkel defect energy (7 eV) compared its bandgap (3.6 eV). This talk discusses recent research on SnO₂-based memristors and the potential synergies of integrating memristors with MEMS.

Microelectronics and microsystems have been part of the key technologies that enabled the incredible pace of development we have seen over the last five to six decades. This paper presents a basic view in terms of technology development supporting new approaches to generation and transfer of knowledge for critical activities, one of the key ones being the ability to capture, store and more efficiently use energy.

Gold has been a biomedical material since ancient times. We shall review the historical uses of gold, in different forms as well as the properties of this metal, which make it very attractive for MEMS and NEMS applications. In particular, we will discuss the synthesis and physic-chemical characteristics of nano particles of gold, emphasizing the role of surface modification, which enables the nano gold to act as a true nano reactor or a nano platform to develop various functions at the nanoscale. Finally, we will describe the use of nano gold for drug targeting and disease detection.

We present the methodology and results of a standard assessment protocol to evaluate disparate SERS substrates that were developed for the Defense Advanced Research Programs Agency (DARPA) SERS Science and Technology Fundamentals Program. The results presented are a snapshot of a collaborative effort between the US Army Edgewood Chemical Biological Center, and the US Army Research Laboratory-Aldelphi Laboratory Center to develop a quantitative analytical method with spectroscopic figures of merit to unambiguously compare the sensitivity and reproducibility of various SERS substrates submitted by the program participants. We present the design of a common assessment protocol and the definition of a SERS enhancement value (SEV) in order to effectively compare SERS active surfaces.

Detecting toxic chemical or biological agents in low concentrations requires a highly specific sensing technique, such as surface-enhanced Raman spectroscopy (SERS). The controlled synthesis of metallic nanocrystals has provided a new class of substrates for more reliable and sensitive SERS applications. The nanocrystal shape plays a major role in designing SERS substrates for maximizing the SERS enhancement factor (EF). Assembling nanocrystals into dimers can further amplify the EF, opening the door to the possibility of single-molecule detection. Here, we briefly discuss our recent work on the synthesis of silver (Ag) nanocrystals and their assembly into dimers and other reliable techniques to form hot spots with sufficiently high EF for single-molecule detection by SERS.

US Military forces are dependent on indigenous water supplies, which are considered prime targets to effect a chemical or biological attack. Consequently, there is a clear need for a portable analyzer capable of evaluating water supplies prior to use. To this end we have been investigating the use of a portable Raman analyzer with surface-enhanced Raman spectroscopy (SERS) sampling systems. The superior selectivity and exceptional sensitivity of SERS has been demonstrated by the detection of single molecules. However, the extreme sensitivity provided by SERS is attributed to "hot spot" structures, such as particle junctions that can provide as much as 10 orders of magnitude enhancement. Unfortunately, hotspots are not evenly distributed across substrates, which results in enhancements that cannot be quantitatively reproduced. Here we present analysis of uniformity for a newly developed substrate and commercial sample vials using benzenethiol and bispyridylethylene, two chemicals often used to characterize SERS substrates, and methyl phosphonic acid, a major hydrolysis product of the nerve agents.

Hand-held instruments capable of spectroscopic identification of chemical warfare agents (CWA) would find extensive use in the field. Because CWA can be toxic at very low concentrations compared to typical background levels of commonly-used compounds (flame retardants, pesticides) that are chemically similar, spectroscopic measurements have the potential to reduce false alarms by distinguishing between dangerous and benign compounds. Unfortunately, most true spectroscopic instruments (infrared spectrometers, mass spectrometers, and gas chromatograph-mass spectrometers) are bench-top instruments. Surface-acoustic wave (SAW) sensors are commercially available in hand-held form, but rely on a handful of functionalized surfaces to achieve specificity. Here, we consider the potential for a hand-held device based on surface enhanced Raman scattering (SERS) using templated nanowires as enhancing substrates. We examine the magnitude of enhancement generated by the nanowires and the specificity achieved in measurements of a range of CWA simulants. We predict the ultimate sensitivity of a device based on a nanowire-based SERS core to be 1-2 orders of magnitude greater than a comparable SAW system, with a detection limit of approximately 0.01 mg m-3.

Two decades of extensive investment in nanomaterials, nanofabrication and nanometrology have provided the global engineering community a vast array of new technologies. These technologies not only promise radical change to traditional industries, such as transportation, information and aerospace, but may create whole new industries, such as personalized medicine and personalized energy harvesting and storage. The challenge today for the defense aerospace community is determining how to accelerate the conversion of these technical opportunities into concrete benefits with quantifiable impact, in conjunction with identifying the most important outstanding scientific questions that are limiting their utilization. For example, nanomaterial fabrication delivers substantial tailorablity beyond a traditional material data sheet. How can we integrate this tailorability into agile manufacturing and design methods to further optimize the performance, cost and durability of future resilient aerospace systems? The intersection of nano-based metamaterials and nanostructured devices with biotechnology epitomizes the technological promise of autonomous systems and enhanced human-machine interfaces. What then are the key materials and processes challenges that are inhibiting current lab-scale innovation from being integrated into functioning systems to increase effectiveness and productivity of our human resources? Where innovation is global, accelerating the use of breakthroughs, both for commercial and defense, is essential. Exploitation of these opportunities and finding solutions to the associated challenges for defense aerospace will rely on highly effective partnerships between commercial development, scientific innovation, systems engineering, design and manufacturing.

Nanocarbon materials, such as carbon nanotubes and graphene, can potentially overcome the short comes in traditional infrared detector materials because of their excellent electrical and optical properties such as adjustable electrical band gap, low dark current, fast optical response time etc. This paper will present the development of an infrared imaging system that is capable of infrared imaging without cooling. The sensing elements of the system are carbon nanotubes and graphene. When they are illumined by an infrared light, the nano devices generate photocurrents, respectively. As a result, infrared images can be presented based on using compressive sensing after the collection of photocurrent from the nano devices. The development of this imaging system overcomes two major difficulties. First, the system uses singlepixel nano photodetector, so the pixel crosstalk phenomena of conventional sensor arrays can be eliminated. Second, the requirement of single-pixel unit reduces the manufacturing difficulties and costs. Under this compressive sensing camera configuration, 50 × 50 pixel infrared images can be reconstructed efficiently. The results demonstrated a possible solution to overcome the limitation of current infrared imaging.

There is a continued interest in the terahertz (THz) spectral range due to potential applications in spectroscopy and imaging. Real-time imaging in this spectral range has been demonstrated using microbolometer technology with external illumination provided by quantum cascade laser based THz sources. To achieve high sensitivity, it is necessary to develop microbolometer pixels using enhanced THz absorbing materials. Metal films with thicknesses less than the skin depth for THz frequencies can efficiently absorb THz radiation. However, both theoretical analysis and numerical simulation show that the maximum THz absorption of the metal films is limited to 50%. Recent experiments carried out using a series of Cr and Ni films with different thicknesses showed that absorption up to the maximum value of 50% can be obtained in a broad range of THz frequencies. A further increase in absorption requires the use of resonant structures. These metamaterial structures consist of an Al ground plane, a SiO₂ dielectric layer, and a patterned Al layer. Nearly 100% absorption at a specific THz frequency is observed, which strongly depends on the structural parameters. In this paper, the progress in the use of thin metal films and metamaterial structures as THz absorbers will be described.

Plasmon excitation in the two dimensional electron gas (2DEG) of grating-gated high electron mobility transistors (HEMTs) gives rise to terahertz absorption lines, which may be observed via transmission spectroscopy. Such absorption resonances may alter the channel conductance, giving a means for tunable terahertz detection. The transmission spectrum may be calculated analytically by making simplifying assumptions regarding the electron distribution. Such assumptions can limit the usefulness of such analytical theories for device optimization. Indeed, significant differences between experimentally observed resonances and theory have been noted and explained qualitatively as due to additional, unanticipated, sheets of charge in the device. Here, we explore finite element method (FEM) simulations, used to obtain realistic carrier profiles. Simulated plasmon spectra do not support previous explanations of red-shifting due to interactions with additional neighboring charge distributions. Simulations do show unexpected plasmon resonances associated with the unanticipated sheet charge, named virtual-gate, as well as the expected resonances associated with the 2DEG. Plasmonic modes determined from these investigations are able to account for the measured absorption lines which were previously thought to be red-shifted 2DEG plasmons. Additionally, the same simulation approach was applied to proposed graphene-based devices to investigate their plasmon resonance spectra.

We report on the effect of population inversion associated with the electron and hole injection in graphene pi- n structures at the temperatures 200K-300K. It is assumed that the recombination and energy relaxation of electrons and holes is associated primarily with the interband and intraband processes assisted by optical phonons. The dependences of the electron-hole and optical phonon effective temperatures on the applied voltage, the current-voltage characteristics, and the frequency-dependent dynamic conductivity are obtained. In particular, at low and moderate voltages the injection can lead to a pronounced cooling of the electron-hole plasma in the device i-section to the temperatures below the lattice temperature. At higher voltages, the current and electronhole and phonon temperature dependences on voltage exhibit the S-shape. At a certain values of the applied voltage the frequency-dependent dynamic conductivity can be negative in the terahertz range of frequencies. The electron-hole plasma cooling substantially reinforces the effect of negative dynamic conductivity and promotes the realization of terahertz lasing. It is demonstrated that the heating of optical phonon system hinders the realization of negative dynamic conductivity and terahertz lasing at the room temperatures.

The ability of millimetre wave and terahertz systems to penetrate clothing is well known. The fact that the transmission of clothing and the reflectivity of the body vary as a function of frequency is less so. Several instruments have now been developed to exploit this capability. The choice of operating frequency, however, has often been associated with the maturity and the cost of the enabling technology rather than a sound systems engineering approach. Top level user and systems requirements have been derived to inform the development of design concepts. Emerging micro and nano technology concepts have been reviewed and we have demonstrated how these can be evaluated against these requirements by simulation using OpenFx. Openfx is an open source suite of 3D tools for modeling, animation and visualization which has been modified for use at millimeter waves.

Conventional guidelines and approximations useful in macro-scale system design can become invalidated when applied to the smaller scales. An illustration of this is when camera pixel size becomes smaller than the diffraction-limited resolution of the incident light. It is sometimes believed that there is no benefit in having a pixel width smaller than the resolving limit defined by the Raleigh criterion, 1.22 λ F/#. Though this rarely occurs in today's imaging technology, terahertz (THz) imaging is one emerging area where the pixel dimensions can be made smaller than the imaging wavelength. With terahertz camera technology, we are able to achieve sub-wavelength pixel sampling pitch, and therefore capable of directly measuring if there are image quality benefits to be derived from sub-wavelength sampling. Interest in terahertz imaging is high due to potential uses in security applications because of the greater penetration depth of terahertz radiation compared to the infrared and the visible. This paper discusses the modification by INO of its infrared MEMS microbolometer detector technology toward a THz imaging platform yielding a sub-wavelength pixel THz camera. Images obtained with this camera are reviewed in this paper. Measurements were also obtained using microscanning to increase sampling resolution. Parameters such as imaging resolution and sampling are addressed. A comparison is also made with results obtained with an 8-12 μm band camera having a pixel pitch close to the diffractionlimit.

We are utilizing control of molecular processes at the quantum level via the best capabilities of recent laser technology and recent discoveries in optimal shaping of laser pulses to significantly enhance the detection of explosives. Optimal dynamic detection of explosives (ODD-Ex) is a methodology whereby laser pulses are optimally shaped to simultaneously enhance the sensitivity and selectivity of any of a wide variety of spectroscopic methods for explosives signatures while reducing the influence of noise and environmental perturbations. We discuss here recent results using the Gerchberg-Saxton algorithm to provide an optimal shaped laser pulse for selective coherent anti-Stokes Raman signal generation of a single component in a mixture.

QCLs represent an important advance in MWIR and LWIR laser technology. With the demonstration of CW/RT QCLs, large number applications for QCLs have opened up, some of which represent replacement of currently used laser sources such as OPOs and OPSELs, and others being new uses which were not possible using earlier MWIR/LWIR laser sources, namely OPOs, OPSELs and CO₂ lasers. Pranalytica has made significant advances in CW/RT power and WPE of QCLs and through its invention of a new QCL structure design, the non-resonant extraction, has demonstrated single emitter power of >4.7 W and WPE of >17% in the 4.4μm-5.0μm region. Pranalytica has also been commercially supplying the highest power MWIR QCLs with high WPEs. The NRE design concept now has been extended to the shorter wavelengths (3.8μm-4.2μm) with multiwatt power outputs and to longer wavelengths (7μm-10μm) with >1 W output powers. The high WPE of the QCLs permits RT operation of QCLs without using TECs in quasi-CW mode where multiwatt average powers are obtained even in ambient T>70°C. The QCW uncooled operation is particularly attractive for handheld, battery-operated applications where electrical power is limited. This paper describes the advances in QCL technology and applications of the high power MWIR and LWIR QCLs for defense applications, including protection of aircraft from MANPADS, standoff detection of IEDs, insitu detection of CWAs and explosives, infrared IFF beacons and target designators. We see that the SWaP advantages of QCLs are game changers.

Standoff identification of explosive residues may offer early warnings to many hazards plaguing present and future military operations. The greatest challenge is posed by the need for molecular recognition of trace explosive compounds on real-world surfaces. Most techniques that offer eye-safe, long-range detection fail when unknown surfaces with no prior knowledge of the surface spectral properties are interrogated. Inhomogeneity in the surface concentration and optical absorption from background molecules can introduce significant reproducibility challenges for reliable detection when surface residue concentrations are below tens of micrograms per square centimeter. Here we present a coupled standoff technique that allows identification of explosive residues concentrations in the sub microgram per square centimeter range on real-world surfaces. Our technique is a variation of standoff photoacoustic spectroscopy merged with ultraviolet chemical photodecomposition for selective identification of explosives. We demonstrate the detection of standard military grade explosives including RDX, PETN, and TNT along with a couple of common compounds such as diesel and sugar. We obtain identification at several hundred nanograms per centimeter square at a distance of four meters.

We demonstrate contactless detection of solid residues of explosives using mid-infrared laser spectroscopy. Our detection scheme relies on active laser illumination, synchronized with the collection of the backscattered radiation by an infrared camera. The key component of the system is an external cavity quantum cascade laser with a tuning range of 300 cm^-1 centered at 1220 cm^-1. Residues of TNT (trinitrotoluene), PETN (pentaerythritol tetranitrate) and RDX (cyclotrimethylenetrinitramine) could be identified and discriminated against non-hazardous materials by scanning the illumination wavelength over several of the characteristic absorption features of the explosives.

We are developing a technique for the stand-off detection of trace analytes and residues (explosives, hazardous chemicals, drugs, etc.) using photo-thermal infrared imaging spectroscopy (PT-IRIS). Herein, we refer to this technique as "RED" for "Remote Explosives Detection" or "Resonance Enhanced Detection". This approach leverages recent developments in critical enabling micro and nano-technology components. The first component, a compact IR quantum cascade laser (QCL), is tuned to fundamental absorption bands in the analytes and directed to illuminate a surface of interest. The second component, an IR focal plane array (FPA), is used to image the surface and detect any small increase in the thermal emission upon laser illumination. We have demonstrated the technique at up to 30 meters of stand-off distance indoors and in field tests, while operating the lasers below the eye-safe intensity limit (100 mW/cm²). In this manuscript we detail several recent improvements to the method and system, as well as some recent results for explosives on complex substrates such as car panels and fabrics. We also introduce a computational framework for modeling and simulating the optical and thermal phenomena associated with the photothermal process.

Daylight Solutions has pioneered the development and commercialization of quantum cascade laser (QCL) technology for commercial and military markets. Multi-Watt, multi-wavelength QCL-based systems have been manufactured and tested against harsh military environmental requirements for military applications. These self-contained, turn-key systems have been designed to comply with modular open system architecture (MOSA) principles, and have been proven in several different system geometries. This paper will highlight the environmental requirements imposed upon, and performance from, QCL-based laser systems for example military applications.

Here we report work done toward standoff characterization of high-molecular components responsible for forming nano-structures in oil disperse system. Complex physical and chemical studies have been conducted specifically on bitumen extracted from rich and poor grade oil sand from Canada. Standoff characterization of oil disperse system highmolecular components is discussed here based on prospective of ultra-fast broadband tunable MWIR laser absorption spectroscopy.

Ultraviolet photodetectors have attracted increasing attention due to its widespread use in civilian and military fields in the past decades. Many kinds of inorganic and organic materials have been used for UV photodetectors so far. ZnO is one of the most prominent semiconductors among them, because it has a wide-band-gap of ~3.35 eV and a large exciton binding energy of 60 meV. As for ZnO nanostructures, they play important roles in developing UV photodetectors. It is fair to state that ZnO nanostructures are probably the most important nanostructures that present excellent performance in photodetectors. In this review, we will describe state-of-the-arts UV photodetectors based on ZnO nanostructures and our recent progress on highly sensitive ZnO hybrid UV photodetector with specific detectivity up to 3.4 ×10¹⁵ Jones.

The dual-axis piezoelectric tilt measurement device presented in this paper is modeled using a proposed methodology that generates a self-calibrating representation of the sensor's output around two axes. Typically, when a piezo-based sensor is developed, its output is modeled as a direct function of its geometric, electro-mechanical and piezoelectric properties. This means that an accurate representation of the sensor's output requires an accurate knowledge of its characteristics. In piezoelectric MEMS applications however, such information is either not available, or is provided in the form of approximate values which are susceptible to external stimuli. The method proposed in this paper models the direct piezoelectric effect as a function of genetic data provided a priori about the operation of a piezo-system. The resulting model is shown to be independent of any system-specific characteristics or any external stimuli. The impact that these parameters exhibit on the output of the sensor is carried implicitly by the genetic data which is generated through calibration. The validity of the proposed model is demonstrated through simulations performed on a new piezoelectric device for dual-axis tilt measurement. These results show a considerable accuracy under variations in the operating conditions, such as temperature.

Reliable SERS-based chemical sensors are attainable with the proper design of nanostructures on the enhancing surface. This proceeding addresses techniques for the immobilization and assembly of metal nanoparticles on substrates and the analysis of the reliability of these techniques with respect to producing effective SERS-based sensors. The fabrication methods that will be addressed are: the "vertical deposition" of nanoparticles on topography-textured substrates using capillary forces; the electrophoretic deposition of nanoparticles in templates prepared by e-beam lithography; and the assembly of nanoparticles through electrostatic interactions between the particles and microphase segregated block-copolymer films. Notably, the use of self-assembly makes these methods economically favorable. Our studies address both large area substrates and localized nanoscale structures. The properly-designed self-assembly approaches do not compromise the accuracy of the calculated enhancement factors, since no assumptions are made regarding the volume of the hot-spots. The reliability of the fabrication techniques is evaluated through the distribution of the enhancement factor values measured in hundreds of sensing sites. Correlations between Raman enhancement, geometry of aggregation and plasmon resonances will be presented. Optimizations of the SERS enhancement and the SERS substrate reliability were achieved through two strategies: (1) by controlling the inter-particle distance between metal nanoparticles in a two-dimensional lattice, and (2) by controlling the number and position of nanoparticles in small isolated clusters.

Stability is an important factor in the study of electrostatic MEMS switches and sensors. Their response is signicantly improved by either applying a large dc bias or by depositing a prescribed value of charge on the oating electrodes. This charge is related to the pull-in voltages. Measurement of charge without causing loading is recommended; so instead of incorporating any eld operated transistor circuitry for this purpose, methods are developed to relate the charge magnitude to the dynamical response of the actuators. Elata et al. developed ecient and reliable ways of charge monitoring without causing loading to the device. These methods rely on energy of the system instead of performing integration in the time domain. Based on their work, this paper examines the alterations in the dynamic response of actuators. The positive and negative pull-in voltages in the voltage displacement plane are symmetrically located with respect to charge on the oating electrode. This fact is exploited to carry out indirect charge measurement from the average of the two pull-in values. A regression scheme is proposed that predicts the charge from the voltage shift based on limited measurements of capacitance of the actuator.

Ultra-short laser pulses may affect bandgap material in a way of changing material optical, electronic, and magnetic properties. Result of ultra-short pulse and band gap material interaction is a combination of multiple well known physical effects that occur when photons at very high rate changing material properties for a short time. Combinations of such effects can be described as Ultrafast Bandgap Photonics phenomena. Key stone of Ultrafast Bandgap Photonics is in time difference between excitation and relaxation processes in bandgap material. Time difference allows to use Ultrafast Bandgap Photonics in applications ranging from low observables to optically induced ambient temperature superconductivity.

This paper presents the fabrication of large-aperture low-pressure chemical-vapour deposited (LPCVD) Bragg reflectors utilizing low-stress polysilicon (PolySi) and silicon-rich silicon nitride (SiN) λ/4-thin film stacks. These structures can function as the upper mirror in a MEMS FPI device. High aspect-ratio mirror membranes were successfully released for 5 - 10 mm diameter range by sacrificial SiO₂ etching in HF vapour. Optical simulations are presented for the Bragg reflector test structures designed for FPIs operating in the NIR range and the properties such as release yield and mechanical stability of the released LPCVD deposited polySi-SiN mirror membranes are compared with similar released atomic layer deposited (ALD) Al₂O₃-TiO₂ λ/4-thin film mirror stacks. The realization of these Bragg reflector structures is the first step in the process integration of large-aperture MEMS FPI for miniature NIR imaging spectrometers, which can be applied to a variety of applications ranging from medical imaging and diagnostics to spaceand environmental monitoring instrumentation.

The threat of terrorism and the need for homeland security calls for advanced technologies to detect the concealed explosives safely and efficiently. We demonstrated highly sensitive and selective detection of traces of nitroaromatic explosive compounds by functionalizing gallium nitride (GaN) nanowires with titanium dioxide (TiO₂) nanoclusters to address this issue. The hybrid sensor devices were developed by fabricating two-terminal devices using individual GaN nanowires (NWs) followed by the deposition of TiO₂ nanoclusters (NCs) using sputtering technique. The photo-modulated GaN/TiO₂ NWNC hybrids showed remarkable selectivity to benzene and related aromatic compounds, with no measureable response for other analytes at room temperature. This paper presents the sensing characteristics of GaN/TiO₂ nanowire-nanocluster hybrids towards the different aromatic and nitroaromatic compounds at room temperature. The GaN/TiO₂ hybrids were able to detect trinitrotoluene (TNT) concentrations as low as 500 pmol/mol (ppt) in air and dinitrobenzene concentrations as low as 10 nmol/mol (ppb) in air in approximately 30 s. The noted sensitivity range of the devices for TNT was from 8 ppm down to as low as 500 ppt. The detection limit of Dinitrotoluene , nitrobenzene , nitrotoluene, toluene and benzene in air is 100 ppb with a response time of ~ 75 s. The devices show very sensitive and selective response to TNT when compared to interfering compounds like toluene. Integration of this nano-scale technology could lead to tiny, highly sensitive, selective, low-power and smart explosive detectors that could be manufactured cheaply in large numbers.

We report the systematic etching profile of GaN nano pillar structures using inductively coupled plasma (ICP) etching techniques. We were able to control the side wall angle, shape and dimension of such nanoscale structures by carefully selecting the etching parameters. We present the effects of variations of the etch parameters, such as ICP power, RF power, chamber pressure, and substrate temperature on the etch characteristics, such as etch rate, sidewall angle, anisotropy, mask erosion, and surface roughness. Utilizing such methods, we demonstrated the fabrication of nanoscale structures with designed shapes and dimensions over large area. Nanocolumns with diameter of 120 nm and height of 1.6 μm with sidewall angle of 86° (90° represent a vertical sidewall) were fabricated. Nanocones with tip diameter of 30 nm and height of 1.6 μm with sidewall angle of 70° were demonstrated. The structures produced by such top-down method could potentially be used in light-emitting diodes, laser diodes, photodetectors, vertical transistors, fieldemitters, and photovoltaic devices.

The novel IonCCD^TM, a charged-particle-sensitive pixelated detector, was used as an anode to directly read out the electrons exiting from the back of a micro-channel plate (MCP). The IonCCD chip is a 51-mm-long linear array of 2126 pixels, each of 21-μm width and 1.5-mm height, resulting in a 24-μm pitch. Both simulations and experiments were performed to assess MCP-IonCCD performance. The assembled MCP-IonCCD test apparatus consisted of a standard, off-the-shelf, 25-mm-diameter circular MCP. The IonCCD was mounted at proximity focus. The IonCCD eliminates the requirement for a phosphorus screen (after glow and electrons-to-photons conversion), as well as the need for a transformer lens or fiber coupling, as commonly used in imaging devices such as electro-optical ion detector systems (EOIDs). Another advantage is the elimination of the rather high voltages (~5-kV) that are typically needed for effective electron-to-photon conversion. Finally, the IonCCD should preclude any photon-scattering-induced spatial resolution degradation. Our early MCP-IonCCD tests showed that the MCP permits an immediate 10³-10⁴ gain, with virtually no additional noise beyond that attributed to the IonCCD alone. The high gain allows the use of lower IonCCD integration times, which will motivate the development of faster IonCCD readout speeds (currently at 2.7 ms) to match the 2-kHz 1D chip. The presented detector system exhibits a clear potential not only as a trace analysis detector in scan-free mass spectrometry, ion mobility and electron spectroscopy but more importantly as a means to achieve simpler, more compact and robust 2D imaging detectors for photon and particle imaging applications.

Traditional optical components have many drawbacks such as bulky size and suffering from the diffraction limits. In order to solve these problems, optical antennas have been proposed recently. It overcomes the constraints imposed by conventional optical devices, allowing unprecedented control of light-matter interactions within sub-wavelength volume. Up until now, almost all of the existing optical antennas can only operate at single fixed frequency. This has highlighted the need for designing optical antennas covering multiple working frequencies or broad frequency band to achieve more design and application flexibility. Motivated by this factor, in this paper, we design and investigate new optical antennas with multi-frequency and broadband operations. Specifically, we investigate several optical antenna topologies to introduce multiple resonant peaks. Potential candidate designs include the stepped-junction optical antenna, and the multi-junction optical antenna. Moreover, based on the concept of multiple-pair nano-dimer structure, broadband optical antennas are investigated, which can further enable us to control light over broad spectrum.