This PDF file contains the front matter associated with SPIE Proceedings Volume 7318, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

EO/IR Sensors have been developed for a variety of Military Systems Applications. These include UV, Visible, SWIR, MWIR and LWIR Sensors. The conventional SWIR Sensors using InGaAs Focal Plane Array (FPA) can operate in 0.4 - 1.8 micron region. Similarly, MWIR Sensors use InSb and HgCdTe based FPA's that are sensitive in 3-5 and 8-14 micron region. DOD investments in the last 10 years have provided the necessary building blocks for the IR Sensors that are being deployed in the field. In this paper, we discuss recent developments and work under way to develop Next Generation nanostructure based EO/IR detectors that can potentially cover UV, Visible and IR regions of interest. The critical technologies being developed include ZnO nanostructures with wide band gap for UV detection and Carbon Nanostructures that have shown the feasibility for IR detection. Experimental results on ZnO based nanostructures demonstrate enhanced UV sensitivity and path forward for larger arrays. Similarly, recent works on carbon nanostructures have shown the feasibility of IR detection. Combining the two technologies in a sensor can provide multispectral capability.

We developed a novel method for three-dimensional heterogeneous integration of devices based on any semiconductor material on a pliant surface with arbitrary surface profile. Arrays of optical detectors in the form of vertically oriented micro/nano-pillars with diverse bandgaps and physical properties are fabricated via synthetic bottom-up or transformative top-down approaches on a single crystal surface and then transferred to a different target surface using a polymer assisted shear-fracturing process. The original wafers are used repeatedly for generating more devices and are never consumed. Ohmic contacts with low contact resistance are formed for individual electrical addressing of each layer of sensors using metals and/or conducting polymer such as PAni and PEDOT:PSS. The method offers an opportunity for device fabrication with low fill factor contributing to lower dark current, reduced parasitic capacitance and higher efficiency of light absorption.

The physics of operation of nanotube NEMS devices is reviewed. Special attention is paid to non-classical effects, rarely described in MEMS analysis, such as van derWaals/Casimir interactions, quantum effects in electrostatics, atomistic parameterization of elasticity. As an example of a breakdown of a classical MEMS theory, the NEMS scaling limitation is derived in a lump model taking into account van der Waals/Casimir attraction.

Carbon Nanotubes were synthesized on passive scanning probes and silicon nitride membranes using Chemical Vapor Deposition (CVD) techniques. The catalysts precursors were deposited using a "wet" technique. The synthesized CNT were subsequently characterized using Scanning Electron Microscopy (SEM).

The ability to deposit two different materials with nanoscale precision at user specified locations is a very important attribute of dip pen nanolithography (DPN). However, the potential of DPN goes beyond simple deposition since DPN used in conjunction with lateral force microscopy (LFM) allows site-specific investigations of nanoscale properties. In this work, we use two different inks, 16-Mercaptohexadecanoic acid (MHA) and 1-octadenethiol (ODT) to show sitespecific dual ink DPN enabled exclusively by our proprietary software. A diamond-dot pattern was created by using a layer-to-layer alignment (LLA) algorithm which enables the MHA (diamond) to be written concentric with the ODT (central dot) pattern. This simple demonstration of multi-ink DPN is not specific to alkanethiol ink systems, but is also applicable to other multi-material patterning, interaction and exchange studies.

We have developed manufacturable approaches to form single, vertically aligned carbon nanotubes, where the tubes are centered precisely, and placed within a few hundred nm of 1-1.5 μm deep trenches. These wafer-scale approaches were enabled by chemically amplified resists and inductively coupled Cryo-etchers to form the 3D nanoscale architectures. The tube growth was performed using dc plasmaenhanced chemical vapor deposition (PECVD), and the materials used for the pre-fabricated 3D architectures were chemically and structurally compatible with the high temperature (700 °C) PECVD synthesis of our tubes, in an ammonia and acetylene ambient. The TEM analysis of our tubes revealed graphitic basal planes inclined to the central or fiber axis, with cone angles up to 30° for the particular growth conditions used. In addition, bending tests performed using a custom nanoindentor, suggest that the tubes are well adhered to the Si substrate. Tube characteristics were also engineered to some extent, by adjusting growth parameters, such as Ni catalyst thickness, pressure and plasma power during growth.

InP nanowires were grown by metalorganic chemical vapor deposition (MOCVD) on a quartz substrate that was covered with a layer (100 nm) of non-single crystal hydrogenated silicon (Si:H) demonstrating that single crystalline platforms are not a requirement for single crystal semiconductor nanowire growth. Scanning electron microscopy (SEM), X-ray diffraction (XRD), photoluminescence (PL), Raman spectroscopy and Cathode luminescence (CL) were used to characterize the structural and optical properties of the nanowires. The nanowires grew in random directions with uniform size distribution and with high density. Two different crystallographic habits were found to grow as has been reported previously and the suggestion that the differing crystallographic habits are due to distinct wurtzite and zincblende crystal structures1 is further substantiated by the XRD profile presented in this paper. The XRD profile suggests that nanowires either having hexagonal-close-packed or face-centered cubic lattice are present. The Raman spectrum shows peaks associated with transverse optical (TO) and longitudinal optical (LO) branches of InP. The Raman peaks closely match those of bulk InP. CL of a single InP nanowire was to study the variations in luminescence along the long axis of the tapered nanowire from the base (~250 nm in diameter) to the tip (~10 nm in diameter), however no substantial variation in luminescence was observed along the long axis of the nanowires. Microscopic carrier recombination dynamics of the nanowires will be discussed with the view towards nanowire-based optical sensors.

We report the results of scanning micro-Raman spectroscopy obtained on Au-Ag nanowires for a variety of chemical warfare agent simulants. Rough silver segments embedded in gold nanowires showed enhancement of 10⁵ - 10⁷ and allowed unique identification of 3 of 4 chemical agent simulants tested. These results suggest a promising method for detection of compounds significant for security applications, leading to sensors that are compact and selective.

Point-of-care (POC) diagnostics have tremendous potential to improve human health in remote and resource-poor settings. However, the design criteria for diagnostic tests appropriate in settings with limited infrastructure are unique and challenging. Here we present a custom optical reader which quantifies silver absorbance from heterogeneous immunoassays. The reader is simple and low-cost and suited for POC diagnostics.

Digital microfluidic systems (DMFS) manipulate liquid droplets with volumes in submicroliter range in two dimensional arrays of cells. Among possible droplet actuation mechanisms, Electrowetting-on-dielectric (EWOD) actuation has been found to be most feasible and advantageous because of low power consumption, ease of signal generation and basic device fabrication. In EWOD based DMFS, droplets are actuated by applying an electric field and thus increasing the wettability on one side of the droplet. In this paper, we show that the EWOD actuation of a droplet can be modeled as a closed loop system having unity feedback of position. Electrode, dielectric and droplet are modeled as a capacitor with variable area as the droplet, considered as a conductor, moves over the dielectric layer. The EWOD force depends on the rate of change of droplet area over the actuated electrode, which in turn depends on the direction of motion and the position of the droplet between the actuated and previous electrode. Thus, EWOD actuation intrinsically utilizes the droplet position to generate sufficient force to accelerate the droplet. When the droplet approaches the final position, the magnitude of force reduces automatically so the droplet decelerates. In case the droplet has sufficient momentum to exceed the final position, the EWOD force, according to the model, will act on the opposite side of the droplet in order to bring it back to the desired position. The dynamic response has been characterized using the proposed model for different droplet sizes, actuation voltages, dielectric thicknesses and electrode sizes.

Anthropomorphous robotic hands at microscales have been developed to receive information and perform tasks for biological applications. To emulate a human hand's dexterity, the microhand requires a master-slave interface with a wearable controller, force sensors, and perception displays for tele-manipulation. Recognizing the constraints and complexity imposed in developing feedback interface during miniaturization, this project address the need by creating an integrated cyber environment incorporating sensors with a microhand, haptic/visual display, and object model, to emulates human hands' psychophysical perception at microscale.

In February 2008 the US Army Research Laboratory established the Micro Autonomous Systems and Technology Collaborative Technology Alliance, in which research is performed by an alliance of government, academic and industrial researchers. The research, grounded in microsystem mechanics, microelectronics, algorithms for autonomy, and integration, is focused on addressing four cross-cutting thrusts: mobility and navigation of palm-sized platforms, sensing and perception on palm-sized platforms, sensing, perception, and navigation of a collection of platforms, and the modeling, simulation, experimentation, and validation of such platforms individually and as a collective ensemble. This article reviews the operational and technical objectives of the program, and overviews some of the research conducted to achieve them.

We envision situational awareness developed through warfighters deployment of a system of diverse mobile, communicating platforms that cooperate to provide full coverage of interior and exterior spaces. The goal of the ARL-MAST Center on Microsystem Mechanics is to perform the fundamental research that will enable flying and ambulating platforms to achieve the required mobility for the proposed missions and environments. In this paper the fundamental issues and challenges associated with achieving this goal will be discussed.

The Army Research Laboratory established the Micro Autonomous Systems and Technology (MAST) Collaborative Technology Alliance (CTA) program in 2008 to leapfrog technological barriers toward achieving the autonomous operation of a collaborative ensemble of multifunctional, mobile microsystems. This goal will be realized through fundamental advancements by the MAST alliance, composed of four centers with focused research activities in Microsystems Mechanics, Processing for Autonomous Operation, Microelectronics, and Integration. A team of researchers assembled by the University of Michigan was chosen to lead the microelectronics center. This paper provides an overview of research activities in the MAST Microelectronics Center. Research activities in this center are organized around five major research thrusts: 1) sensing, 2) low power processing, 3) communications, 4) navigation, 5) efficient power generation. Such activities are envisioned to enable micro-autonomous sensor platforms by developing novel electronic sensors and devices having the following attributes: low power and power efficient characteristics, low mass and volume, enhanced functionality/sensitivity, survivability, durability, extended operation capability, low cost, and fault tolerance. Fundamental advances in microelectronics will be accomplished through implementation of bio-mimetic and bio-inspired techniques and technologies, utilization of Nano/micro fabrication processes, and incorporation of novel materials in fabrication of components and subsystems.

The vision for the Micro Autonomous Systems Technologies MAST programis to develop autonomous, multifunctional, collaborative ensembles of agile, mobile microsystems to enhance tactical situational awareness in urban and complex terrain for small unit operations. Central to this vision is the ability to have multiple, heterogeneous autonomous assets to function as a single cohesive unit, that is adaptable, responsive to human commands and resilient to adversarial conditions. This paper represents an effort to develop a simulation environment for studying control, sensing, communication, perception, and planning methodologies and algorithms.

The US Army Research Laboratory has assembled a Collaborative Technology Alliance (CTA) for the development of Micro Autonomous Systems and Technology (MAST). It is envisioned that an ensemble of microsystems with autonomous behavior will improve situational awareness for a wide range of small unit operations, especially in urban environments. Due to the breadth of missions and scale of the systems, the MAST program has a profound need to pursue microsystem designs that simultaneously optimize multifunctionality, robustness, adaptability as well as affordability. Our inspiration comes from animal physiology, which contains many examples of components that support multiple functions and capabilities in a highly integrated, efficient fashion. Here we outline our approach for designing both individual microsystems and a system of microsystems based on inspiration from biology.

Meeting the requirement of endurance and mission duration is one of the major challenges in the design of micro-autonomous vehicles. Various power source options and their properties for micro-autonomous vehicles are reviewed. Strategies to maximize the mission duration within the constraints of mass and volume for micro-autonomous vehicles are discussed. This paper explores the use of hybridization, multifunctional integration concepts, elimination of ancillary components and operational strategies as means of achieving the endurance goals for micro-autonomous vehicles.

This paper considers a landing problem for an MAV that uses only a monocular camera for guidance. Although this sensor cannot measure the absolute distance to the target, by using optical flow algorithms, time-to-collision to the target is obtained. Existing work has applied a simple proportional feedback control to simple dynamics and demonstrated its potential. However, due to the singularity in the time-to-collision measurement around the target, this feedback could require an infinite control action. This paper extends the approach into nonlinear dynamics. In particular, we explicitly consider the saturation of the actuator and include the effect of the aerial drag. It is shown that the convergence to the target is guaranteed from a set of initial conditions, and the boundaries of such initial conditions in the state space are numerically obtained. The paper then introduces parametric uncertainties in the vehicle model and in the time-to-collision measurements. Using an argument similar to the nominal case, the robust convergence to the target is proven, but the region of attraction is shown to shrink due to the existence of uncertainties. The numerical simulation validates these theoretical results.

This paper presents the design, analysis, and fabrication of an array of microflap actuators that can produce a substantial aerodynamic force for course corrections of Micro Air Vehicles (MAVs) and low speed projectiles. In the past, several actuation principles, including microjet, magnetic and bubble actuators, and flapping wings have been proposed, and had varying degrees of success. In this paper, we discuss the benefits and drawbacks of past attempts, and the technology that can be used to address the microflap steering problem. We propose a hybrid microflap actuation scheme that combines two types of actuators including: 1) a MEMS fabricated "active" microactuator connected to a microflap, and 2) a "passive" fluidic channel system that harvests the potential energy in the high pressure field on the leading edge of the MAV or high speed projectile to achieve a desired deflection. An array of microflap actuators was prototyped using silicon MEMS fabrication and microassembly. A Silicon On Insulator (SOI) wafer with 100 micron thick device layer was used to as a substrate material to fabricate microflap structures with springs. Front and back side DRIE process was used to etch and release the microstructures including microflaps. Then, the microactuator was assembled on top of the microflap. The static and dynamic behaviors of a microflap were measured using a laser displacement sensor and were compared to the analytic model. In the near future, a prototyped microflap will be tested inside of a wind tunnel to measure the lift and drag at various air speeds.

An optical communication system suitable for voice communication, data retrieval from remote sensors and identification had been designed, built and tested. The system design allows operation at ranges of several hundred meters. The heart of the system is a modulated MEMS mirror that is electrostatically actuated and changes between a flat reflective state and a corrugated diffractive state. A process for mass producing these mirrors at low cost was developed and implemented. The mirror was incorporated as a facet in a hollow retro-reflector, allowing temporal modulation of an interrogating beam and the return of the modulated beam to the interrogator. This modulator unit thus consists of a low power, small and light communication node with large (about 60°) angular extent. The system's range and pointing are determined by the interrogator /detector / demodulator unit (the transceiver), whereas the communicating node remains small, low power and low cost. This transceiver is comprised of a magnified optical channel to establish line of sight communication, an interrogating laser at 1550nm, an avalanche photo diode to detect the return signal and electronics to drive the laser and demodulate the returned signal and convert it to an audio signal. Voice communication in free space was demonstrated at ranges larger than 200 meters. A new retro-reflector design, incorporating more modulated mirrors had been constructed. This configuration was built and tested. Its performance and advantages as compared to the single mirror retro-reflector are discussed. An alternative system design that allows higher bandwidth data transmission is described

In 1985, HP introduced the ThinkJet - the first low-cost, mass-produced thermal inkjet printer. Providing a reasonable alternative to noisy dot matrix printers, ThinkJet set the stage for subsequent generations of HP thermal inkjet technology (TIJ). With each new generation, HP TIJ products provided new standards for print quality, color, and an unprecedented cost/performance ratio. Regarded as the first and most successful commercial MEMS technology, the development of HP's TIJ printheads required multidisciplinary innovation in fluid dynamics, bulk and surface micromachining, large-scale integration of electronics, packaging, and high volume MEMS manufacturing. HP's current TIJ printhead products combine Pentium-class addressing circuitry, high voltage mixed-signal driver electronics, dense electrical interconnects, and up to 3900 high-precision microfluidic devices - all on a single silicon chip. In this paper, we will provide a brief history of HP's TIJ technology and discuss how the unique capabilities that were required to advance the state-of-the-art of TIJ printheads are now providing a platform for the development of new MEMS devices and systems.

Performance of electrostatic actuators used in MEMS devices is severely limited by the stability considerations that are related to the pull-in parameters. The static and dynamic responses of electrostatic actuators driven by single as well as multiple voltage excitations are studied with an aim of estimating these pull-in voltage and distance parameters. A normalized Hamiltonian formulation is adopted and the resulting equations are solved analytically and also numerically using an iterative scheme. Recently a numerical α-line method has been proposed to extract the pull-in parameters. Scanning along the α-lines by voltage and displacement iteration schemes were studied. Estimating the intersection of the α-lines with the pull-in hypersurface indicates maximal voltage variable. We revisit these two iteration schemes and propose few insights to improve the convergence. Convergence of the parameters to the theoretical values is found to be smooth. This approach helps us to generalize the technique for more complicated geometries.

MEMS micro-mirror technology offers the opportunity to replace larger optical actuators with smaller, faster ones for lidar, network switching, and other beam steering applications. Recent developments in modeling and simulation of MEMS two-axis (tip-tilt) mirrors have resulted in closed-form solutions that are expressed in terms of physical, electrical and environmental parameters related to the MEMS device. The closed-form analytical expressions enable dynamic time-domain simulations without excessive computational overhead and are referred to as the Micro-mirror Pointing Model (MPM). Additionally, these first-principle models have been experimentally validated with in-situ static, dynamic, and stochastic measurements illustrating their reliability. These models have assumed that the mirror has a rectangular shape. Because the corners can limit the dynamic operation of a rectangular mirror, it is desirable to shape the mirror, e.g., mitering the corners. Presented in this paper is the formulation of a generalized electrostatic micromirror (GEM) model with an arbitrary convex piecewise linear shape that is readily implemented in MATLAB and SIMULINK for steady-state and dynamic simulations. Additionally, such a model permits an arbitrary shaped mirror to be approximated as a series of linearly tapered segments. Previously, "effective area" arguments were used to model a non-rectangular shaped mirror with an equivalent rectangular one. The GEM model shows the limitations of this approach and provides a pre-fabrication tool for designing mirror shapes.

The capabilities of future mobile communication devices will extend beyond merely transmitting and receiving voice, data, and video information. For example, first responders such as firefighters and emergency workers will wear environmentally- aware devices that will warn them of combustible and toxic gases as well as communicate that information wirelessly to the Command and Control Center. Similar sensor systems could alert warfighters of the presence of explosives or biological weapons. These systems can function either in the form of an individual stand-alone detector or part of a wireless sensor network. Novel sensors whose functionality is enhanced via nanotechnology will play a key role in realizing such systems. Such sensors are important because of their high sensitivity, low power consumption, and small size. This talk will provide an overview of some of the advances made in sensors through the use of nanotechnology, including those that make use of carbon nanotubes and nanoparticles. Their applicability in mobile sensing and wireless sensor networks for use in national security and public safety will be described. Other technical challenges associated with the development of such systems and networks will also be discussed.

We have fabricated field-effect transistor (FET) structures using arrays of carbon nanotubes (CNTs) as the conducting channel by using chemical vapor deposition to achieve in-plane growth from nanometer-scale Ni dot patterns on the Au/Cr metal electrode pairs as catalyst tips. Detailed studies of the transfer characteristics of the CNT-FETs have been carried out as a function of the number of CNTs bridging the contact gap. Both, ambipolar and unipolar FET behaviors have been observed at room temperature. Devices containing 12 (6) CNTs bridging the gap display CNT-FET on/off ratios of 2 (4), respectively. Best results have been achieved for devices containing 3 semiconducting CNTs displaying pronounced on/off ratios up to 370 at room temperature. In addition, a correlation between source-drain current and optical illumination has been observed, indicating a photoeffect of the CNT arrays. The measured photocurrent depends linearly on the source-drain voltage indicating that the generated electron-hole pairs are effectively separated by the applied bias, making such devices of interest for photovoltaic applications. The demonstrated access to individual CNTs with pronounced semiconducting behavior opens the possibility to form more advanced nanoelectronic structures such as CNT quantum dots with the ultimate goal to realize single electron memory elements operating at room temperature.

There is a need for accurate and instant measurement of pH values in a wide range of applications. The research on miniaturized polymer based pH sensors has recently emerged due to the progress made in polymer materials science. Novel method of manufacturing micro sensors arrays for biomedical applications using BioForce NanoeNabler^TM is reported. This nanopatterning system uses a liquid dispensing process via specially designed surface patterning tool (SPT), which is microfabricated cantilever with an integrated passive microfluidic system. During the deposition process, which typically takes less than 100 msec, SPT end touches the surface and a volume of fluid is instantly transferred. The NanoeNabler^TM can deliver attoliter to picoliter volumes of liquid with a high degree of spatial accuracy, which resulted in sensor heads measuring 1-2.5 μm to 30 μm. These sensors were developed for biomedical applications, in particular pH monitoring. It is envisaged that findings of this work would form the basis for miniaturised point-of-care diagnostic system. The operation of the sensing elements is based on the properties of polymers, which exhibit a change in their electrical characteristics (such as resistance or capacitance) on exposure to solutions with different concentrations of pH value.

Recent nanotechnology revolutions have cast increased challenges to biotechnology including bio-adhesion of cells. Surface topography and chemistry tailored by the nanotechnology exert significant effects on such applications so that it is necessary to understand how cells migrate and adhere on three-dimensional micro- and nanostructures. However, the effects of the surface topography and chemistry on cell adhesions have not been studied systematically and interactively yet mostly due to the inability to create well-controlled nanostructures over a relatively large surface area. In this paper, we report on the bio-adhesions of varying cell types on well-ordered (post and grate patterns), dense-array (230 nm in pattern periodicity), and sharp-tip (less than 10 nm in tip radius) nanostructures with varying three-dimensionalities (50- 500 nm in structural height). Significantly lower cell proliferation and smaller cell size were measured on tall nanostructures. On a grate pattern, significant cell elongation and alignment along the grate pattern were observed. On tall nanostructures, it was shown that cells were levitated by sharp tips and easily peeled off, suggesting that cell adherence to the tall and sharp-tip nanostructures was relatively weak. The control of cell growth and adherence by the nanoscale surface topographies can benefit the micro- and nanotechnogies-based materials, devices, and systems, such as for anti-biofouling and anti-microbial surfaces. The obtained knowledge by this investigation will also be useful to deal with engineering problems associated with the contact with biological substances such as biomaterials and biosensors.

Nanoscale electric field confinement and enhancement is a well known phenomenon for small particles and flat interfaces. Senspex is using E-Beam lithography to develop nanosensors for the detection of biological and chemical hazards. The sensors that are being developed are a square array of metallic cubes; each cube has dimensions of approximately 100nm x 100nm x 30nm and a pitch of 125nm in the x- and y-directions. Senspex's numerical simulations show that the intense electric field in the minute volume between the cubes will lead to a high probability of detection for small concentrations of analyte in real world situations.

We are pursuing several projects aimed at developing carbon-based nanodevices for sensing, actuation, and nanoelectronics applications. In one project, we are seeking to fabricate and characterize carbon nanotube quantum dots (CNT-QDs) with potential application as future electronic memories with high-performance, bandwidth, and throughput. In a second effort, we have used pulsed laser deposition (PLD) to create thermal bimorph nanoactuators based on multi-wall nano tubes (MWNTs) coated on one side with a thin metal film. Lastly, graphene materials are being studied to investigate its field emission properties for vacuum electronics and to exploit its differential conductivity. These devices have potential in a wide range of applications including sensors, detectors, system-on-a-chip, system-in-a-package, programmable logic controls, energy storage systems and all-electronic systems.

We present a flexible active 2-bit 2-element phased-array antenna (PAA) fully fabricated using ink-jet printing technology. High speed carbon nanotube (CNT) based field effect transistors (FETs) function as switch in the true-time delay line of the PAA. The 2-bit 2-element active PAA is printed out at room temperature on 100μm thick Kapton substrate. The FET switch works well for 5GHz RF signals. An ON-OFF ratio of over 100 is obtained at a low Vds bias of 1.8V. The measured azimuth beamsteering angles of PAA agree well with simulation values.

A new nanoscale electric field sensor was developed for studying triboelectric charging in terrestrial and Martian dust devils. The sensor was fabricated using MEMS techniques, integrated at the system level, and deployed during a dust devil field campaign. The two-terminal piezoresistive sensor consists of a micron-scale network of suspended singlewalled carbon nanotubes (SWCNTs) that are mechanically coupled to a free-standing electrically conductor. Electrostatic coupling of the conductor to the electric field is expected to produce a deflection of the conductor and a corresponding change in nanotube device resistance, based on the known piezoresistive properties of SWCNTs. The projected device performance will allow measurement of the large electric fields for large dust devils without saturation. With dimensions on the 100 μm scale and power consumption of only tens of nW, the sensor features dramatically reduced mass, power, and footprint. Recent field testing of the sensor demonstrated the robustness of suspended SWCNT devices to temperature fluctuations, mechanical shock, dust, and other environmental factors.

A carbon nanotube (CNT) field emission electron gun has been fabricated and assembled as an electron impact ionization source for a miniaturized time-of-flight mass spectrometer (TOF-MS). The cathode consists of a patterned array of CNT towers grown by catalyst-assisted thermal chemical vapor deposition. An extraction grid is precisely integrated in close proximity to the emitter tips (20-35 μm spacing), and an anode is located at the output to monitor the ionization beam current. Ultra-clean MEMS integration techniques were employed in an effort to achieve three improvements, relative to previous embodiments: reduced extraction voltage during operation to be resonant with gas ionization energies, enhanced current transmission through the grid, and a greater understanding of the fundamental current fluctuations due to adsorbate-assisted tunneling. Performance of the CNT electron gun will be reported, and implications for in situ mass spectrometry in planetary science will be discussed.

Because of exceptional mechanical, chemical, and tribological properties, diamond has a great potential to be used as a material for the development of high-performance MEMS and NEMS such as resonators and switches compatible with harsh environments, which involve mechanical motion and intermittent contact. Integration of such MEMS/NEMS devices with complementary metal oxide semiconductor (CMOS) microelectronics will provide a unique platform for CMOS-driven commercial MEMS/NEMS. The main hurdle to achieve diamond-CMOS integration is the relatively high substrate temperatures (600-800°C) required for depositing conventional diamond thin films, which are well above the CMOS operating thermal budget (400 °C). Additionally, a materials integration strategy has to be developed to enable diamond-CMOS integration. Ultrananocrystalline diamond (UNCD), a novel material developed in thin film form at Argonne, is currently the only microwave plasma chemical vapor deposition (MPCVD) grown diamond film that can be grown at 400 °C, and still retain exceptional mechanical, chemical, and tribological properties comparable to that of single crystal diamond. We have developed a process based on MPCVD to synthesize UNCD films on up to 200 mm in diameter CMOS wafers, which will open new avenues for the fabrication of monolithically integrated CMOS-driven MEMS/NEMS based on UNCD. UNCD films were grown successfully on individual Si-based CMOS chips and on 200 mm CMOS wafers at 400 °C in a MPCVD system, using Ar-rich/CH4 gas mixture. The CMOS devices on the wafers were characterized before and after UNCD deposition. All devices were performing to specifications with very small degradation after UNCD deposition and processing. A threshold voltage degradation in the range of 0.08-0.44V and transconductance degradation in the range of 1.5-9% were observed.

Ultrananocrystalline diamond (UNCD) films are promising for radio frequency micro electro mechanical systems (RF-MEMS) resonators due to the extraordinary physical properties of diamond, such as high Young's modulus, quality factor, and stable surface chemistry. UNCD films used for this study are grown on 150 mm silicon wafers using hot filament chemical vapor deposition (HFCVD) at 680°C. UNCD fixed free (cantilever) resonator structures designed for the resonant frequencies in the kHz range have been fabricated using conventional microfabrication techniques and are wet released. Resonant excitation and ring down measurements in the temperature range of 138 K to 300 K were conducted under ultra high vacuum (UHV) conditions in a custom built UHV AFM stage to determine the temperature dependence of Young's Modulus and dissipation (quality factor) in these UNCD cantilever structures. We measured a temperature coefficient of frequency (TCF) of 121 and 133 ppm/K for the cantilevers of 350 μm and 400 μm length respectively. Young's modulus of the cantilevers increased by about 3.1% as the temperature was reduced from 300 K to 138 K. This is the first such measurement for UNCD and suggests that the nanostructure plays a significant role in modifying the thermo-mechanical response of the material. The quality factor of these resonators showed a moderate increase as the cantilevers were cooled from 300 K to 138 K. The results suggest that surface and bulk defects significantly contribute to the observed dissipation in UNCD resonators.

Diamond has long held the promise of revolutionary new devices: impervious chemical barriers, smooth and reliable microscopic machines, and tough mechanical tools. Yet it's been an outsider. Laboratories have been effectively growing diamond crystals for at least 25 years, but the jump to market viability has always been blocked by the expense of diamond production and inability to integrate with other materials. Advances in chemical vapor deposition (CVD) processes have given rise to a hierarchy of carbon films ranging from diamond-like carbon (DLC) to vapor-deposited diamond coatings, however. All have pros and cons based on structure and cost, but they all share some of diamond's heralded attributes. The best performer, in theory, is the purest form of diamond film possible, one absent of graphitic phases. Such a material would capture the extreme hardness, high Young's modulus and chemical inertness of natural diamond. Advanced Diamond Technologies Inc., Romeoville, Ill., is the first company to develop a distinct chemical process to create a marketable phase-pure diamond film. The material, called UNCD® (for ultrananocrystalline diamond), features grain sizes from 3 to 300 nm in size, and layers just 1 to 2 microns thick. With significant advantages over other thin films, UNCD is designed to be inexpensive enough for use in atomic force microscopy (AFM) probes, microelectromechanical machines (MEMS), cell phone circuitry, radio frequency devices, and even biosensors.

Most current micro/nanoelectromechanical systems (MEMS/NEMS) are based on silicon. However, silicon exhibits relatively poor mechanical/tribological properties, compromising applications to several projected MEMS/NEMS devices, particularly those that require materials with high Young's modulus for MEMS resonators or low surface adhesion forces for MEMS/NEMS working in conditions with extensive surface contact. Diamond films with superior mechanical/tribological properties provide an excellent alternative platform material. Ultrananocrystalline diamond (UNCD®) in film form with 2-5 nm grains exhibits excellent properties for high-performance MEMS/NEMS devices. Concurrently, piezoelectric Pb(Zr_xTi_1-x)O₃ (PZT) films provide high sensitivity/low electrical noise for sensing/high-force actuation at relatively low voltages. Therefore, integration of PZT and UNCD films provides a high-performance platform for advanced MEMS/NEMS devices. This paper describes the bases of such integration and demonstration of low voltage piezoactuated hybrid PZT/UNCD cantilevers.

A bi-layer digital microfluidic structure is introduced. The integrated design employs a two-dimensional structure with perpendicular linear electrode arrays controlling x- and y- directional actuation. The introduced structure is capable of electrowetting-based fluid control, and it is presented here as an implementation capable of electrical sensing of the state of fluids within the device. The state of conductive fluids within the bi-layer structure is sampled through differential measurements of conductance values between the x- and y-channels. It is shown here that the features of microdroplets within the device can be effectively mapped onto these differential conductance measurements. An electronic acquisition system is ultimately employed to sense these conductance states and extract the position and size of microdroplets within the device. The complete system is demonstrated here for both single microdroplet and multiple microdroplet implementations.

Rapid and efficient cell purification remains challenging. The use of ferromagnetic Ni nanowires for cell purification is considered superior over magnetic beads. In this study, we explored the opportunity to improve cell purification by using antibody-functionalized Ni nanowires. Antibody (anti-CD31) against mouse endothelial cells (MS-1) was conjugated to Ni nanowire surface by self-assembled monolayers (SAMs) and chemical covalent reaction. The antibody functionalized nanowires were used to purify the MS-1 from a mixture of MS-1 and mouse fibroblast cells (3T3). The nanowire-bound cells were magnetically separated to determine the separation yield of target cells. Furthermore, the proliferation of nanowire-bound cells was studied by MTT cell proliferation assay. This work demonstrates that antibody-functionalized Ni nanowires provide an effective mean to separate cells.

Although thermal IR microemitters making use of Honeywell planar technology remain the devices of choice for the last decade, a significant disadvantage of these devices is their two-level structure, which results in low fill-factor and causes mechanical and thermal stresses between the layers. In this paper, the technology for single-level polycrystalline SiGe thermal microemitters, their design, and performance characteristics are presented. The 128-element linear arrays with a fill-factor of 88 % and a 2.5-μm-thick resonant cavity have been grown by low-pressure chemical vapor deposition and fabricated using surface micromachining technology. The 200-nm-thick 60 × 60 μm2 emitting pixels enforced with a U-shape profile pattern demonstrate time response of 2-7 ms and an apparent temperature of 700 K in the 3-5 and 8-12 μm atmospheric transparency windows. The SiGe device application to the infrared dynamic scene simulation and critical factors that aid their competitiveness over conventional planar two-level design are discussed.

When a micromechanical resonator is moving in air, resistance to motion causes damping which is proportional to the velocity of the resonator. This results in a low quality factor and reduces the sensitivity of the resonator and hence any sensor incorporating the resonator, to any environmental changes. In this paper, a method for increasing the quality factor of micromechanical resonant sensors using velocity feedback is reported. To achieve this, the feedthrough signal between drive and sense connections due to parasitic capacitance is first cancelled in order to remove the previously unreported, undesirable effects that occur from the combination of velocity feedback and capacitive feedthrough. Using this technique, the quality factor of a resonator in air is increased by over two orders of magnitude.

This study focuses on the development of current-perpendicular-to plane (CPP) Giant Magnetoresistance (GMR) of CoNiCu/Cu multilayered nanowire based microfluidic sensors for the detection of magnetic nanoparticles and fluids. The visible measurable variations in electrical voltage due to changes in external magnetic field are later to be monitored in microfluidic biosensor for the detection of toxicants in cells. An early prototype device was fabricated and tested using both an aqueous nonmagnetic medium (water) and a commercially available ferrofluid solution. A magnetic field of 0.01T caused a resistance change of 1.37% for ferrofluid, while a 1.1% GMR was recorded for the water baseline.

Digital microfluidic systems (DMFS) are poised to provide fully automated, high-throughput, dynamically reconfigurable sensing devices superior to those available today. Efficient droplet routing algorithms for these systems have not yet been established, though several solutions have been proposed. Such algorithms are ultimately required to generate droplet movement schedules and must be robust enough to handle the inevitable increases in problem complexity that will come as this technology matures. We have proposed a new solution based on a classic VLSI lineprobe algorithm to meet these demands for the detailed routing of droplets within a multi-stage algorithm. The most significant addition includes a sub-algorithm that calculates the routing complexity for any DMFS configuration based on the size, shape, number, type, and distribution of rectilinear obstacles throughout a DMFS biochip surface. By determining the complexity of the routing of each droplet, routing schedules may be prioritized, minimizing the number of fluidic and time constraint violations that affect high priority droplet routes. The complexity characterizations generated by our algorithm may also be used to create consistent, standardized benchmarks for the evaluation of existing droplet routing solutions. The efficiency of the proposed algorithm has been verified using the simulation presented in this paper.

In this work, we present the design parameters and optimization of the nanoscale gap interdigitated electrodes (IDEs) for hydrogen gas sensing. In order to extract important design parameters and understand the sensor performance, numerical analysis has been carried out for calculating the electric potential, electrical field and surface charge distribution on the IDEs. The results show that the strength of the electrical field drops with the increase in distance from IDEs depending on the gap spacing and finger width of the electrodes. Based on the sensing mechanism of our sensor, the current distribution inside the sensing film is calculated showing that the thin sensing film could result in fast response due to the uniform electrical field distribution. Effects of the gap spacing and width on the sensing performance were investigated numerically. The optimized design of IDEs with 50 nm in gap and 1,000 nm in width shows that the change of electrical field in the thickness direction is much reduced for a given 120 nm-thick sensing layer on top of the IDEs. It is expected that this design responds better to hydrogen induced conductivity change on top surface and leads to shorter response time.

We present a new fabrication method to grow vertically aligned nanowire arrays on a silicon substrate using commercially available anodized aluminum oxide (AAO) and polycarbonate (PC) templates. This technique eliminates the preparation procedure of coating one side of the template with a conductive layer, which is required in most template assisted nanowire growth methods. In this study, vertically aligned nanowires with a high aspect ratio of over 10 were fabricated on silicon substrate by electrodeposition, potentially enabling mass production.