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This PDF file contains the front matter associated with SPIE
Proceedings Volume 7679, including the Title Page, Copyright
information, Table of Contents, and the Conference Committee listing.
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We are exploring nanoelectronic engineering areas based on low dimensional materials, including carbon
nanotubes and graphene. Our primary research focus is investigating carbon nanotube and graphene
architectures for field emission applications, energy harvesting and sensing. In a second effort, we are
developing a high-throughput desktop nanolithography process. Lastly, we are studying nanomechanical
actuators and associated nanoscale measurement techniques for re-configurable arrayed nanostructures with
applications in antennas, remote detectors, and biomedical nanorobots. The devices we fabricate, assemble,
manipulate, and characterize potentially have a wide range of applications including those that emerge as
sensors, detectors, system-on-a-chip, system-in-a-package, programmable logic controls, energy storage
systems, and all-electronic systems.
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At the Space Vehicles Directorate of the Air Force Research Laboratory, we are investigating detector concepts of
use in Space Situational Awareness scenarios. For such applications, the object of interest is usually far away and
often very dim. Our challenge becomes trying to identify such dim/distant space objects. To that end, we are
investigating two optical signal amplification schemes and a wavelength-tunable detector scheme. One of the
amplification schemes involves quantum interference in quantum dots in photonic crystal cavities, and one of the
schemes involves near-field enhancements due to plasmonic interactions on patterned metal surfaces. The tunable
detector scheme involves burying semiconductor quantum dots in one quantum well of a double-quantum-well
structure, and then biasing the structure laterally.
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Nanocrystalline ZnO films prepared by Pulsed Laser Deposition were used to fabricate the first thin film transistors that
operate at microwave frequencies. Unlike more conventional amorphous Si and organic thin film transistors, which are
only suitable for low speed applications, ZnO-based thin film transistors exhibit figure-of-merit device numbers that are
comparable to single crystal transistors. These include on/off ratio of 1012, current density of >400mA/mm and field
effect mobility of 110 cm2/V.s. Parameters, including film growth temperature, gate insulators, and device layout
designs were examined in detail to maximize performance. We have achieved current gain cut-off frequency, fT, and
power gain cut-off frequency, fmax, values of 2.9GHz and 10GHz, respectively with 1.2μm gate length devices
demonstrating that ZnO-based TFTs are suitable for microwave applications.
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Long photocarrier lifetime is a key issue for improving of room-temperature infrared photodetectors. Detectors based on
nanostructures with quantum dot clusters have the strong potential to overcome the limitations in quantum well detectors
due to various possibilities for engineering of specific kinetic and transport properties. Here we review photocarrier
kinetics in traditional QDIPs and present results of our investigations related to the QD structures with vertically
correlated dot clusters (VCDC). Modern technologies allow for fabrication of various VCDC with controllable
parameters, such as the cluster size, a distance between clusters, dot occupation etc. Modeling of photocarrier kinetics in
VCDC structures shows that the photocarrier capture time exponentially increases with increasing of the number of dots
in a cluster. It also exponentially increases as the occupation of a dot increases. At the same time, the capture processes
are weakly sensitive to geometrical parameters, such as the cluster size and the distance between clusters. Compared
with ordinary quantum-dot structures, where the photoelectron lifetime at room temperatures is of the order of 1-10 ps,
the VCDC structures allow for increasing the lifetime up to three orders of magnitude. We also study the nonlinear
effects of the electric field and optimize operating regimes of photodetectors. Complex investigations of these structures
pave the way for optimal design of the room-temperature QDIPs.
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We report a voltage-tunable multispectral quantum dot infrared photodetector with
integrated carbon-nanotube based flexible electronics. Such integrated photodetection
and flexible electronics would not only enhance the detectors functionalities, but also
reduce the time delay by performing image processing locally, making it promising for
adaptive multi-spectral photodetection and sensing.
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The past decade has seen a dramatic development in the infrared imaging systems. New material systems, novel
fabrication schemes and creative read out circuit and system designs have all driven the third generation systems
towards large format focal plane arrays with multicolor capability and high operating temperature. This paper
explores the possibility of development of next generation infrared imagers. Could it be a bio-inspired infrared retina
similar to the human eye? The conjecture is that the next generation systems will have two distinctive features that is
present in the eye. They are (a) the ability to sense multimodal information including spectral, polarization, dynamic
range, phase and (b) the intelligence to only send only small pieces of information to the central processing unit.
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Micro- and Nanotechnology for Health Care Applications
We have developed a number of amphiphilic polymers, comprised of a cluster of cholic acids (4 to 10) linked by a series
of lysines and attached to one end of a linear polyethylene glycol chain (PEG, 2000-5000 Dalton). Under aqueous
condition, such telodendrimers can self-assemble together with hydrophobic payloads to form highly stable micelles
(15-150 nm diameter, size tunable). We used near infrared fluorescence (NIRF) optical imaging technique to study the in
vivo passive accumulation of our nanocarriers (via EPR effect) in different types and stages of tumors. The results
demonstrated that the micelle could preferentially accumulate in many types of tumor xenografts or synografts implanted
in mice. Nanoparticle uptake in solid tumors was found to be much higher than that of lymphoma, which could be
attributed to the relatively low microvascular density in the latter. We have also demonstrated that micelles smaller than
64 nm preferentially targeted xenografts with high efficiency and with low liver and lung uptake, whereas those micelles
at 154 nm targeted the tumor poorly but with very high liver and lung uptake. Telodendrimers decorated with oligolysine
or oligoaspartic acid resulted in high uptake of the nanoparticles into the liver. When decorated with cancer targeting
ligands identified from the one-bead-one-compound (OBOC) combinatorial library methods, the drug-loaded
nanoparticles were rapidly taken up by the target cultured tumor cells causing cell death. In vivo near infra-red optical
imaging studies with hydrophobic fluorescent dye demonstrated that xenograft uptake of the micelles was greatly
enhanced by the cancer targeting peptide.
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The new "EXX" phenomena in macroscopic, microscopic and nanoscopic metal-semiconductor hybrid structures is
described. Here E = extraordinary and XX = magnetoresistance (EMR), piezoconductance (EPC), optoconductance
(EOC), and electroconductance (EEC). This new class of phenomena is based on the control and dominance of the
geometric contributions, e.g. sample shape, lead placement, the presence of inhomogenieties, etc., to the transport
properties of a physical system in contrast to traditional transport phenomena which are dominated by the intrinsic
properties, e.g. mobility, carrier density, band structure, etc. The underlying phyiscs of EXX phenomena is elucidated
with particular emphasis on the use of analytic and finite element analysis methods to quantitatively account for the
observed EXX signal enhancement. The potential application of EXX phenomena to the study of the biologically
relevant properties of cells such as surface charge density will be described.
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There are critical implementation challenges to consider for new digital microfluidic technologies. In dynamic
applications, properties of both the system and the microdroplet are changing in time due to the adsorption of
microdroplet species at the solid-liquid and liquid-vapor interfaces. In this paper, these digital microfluidic dynamic
challenges are overcome through the introduction of real-time sensing submodules. Dynamic sampling has been added
to the actuation mechanisms of the digital microfluidic system, and it is shown that the complete fluid system can be
characterized simultaneously by measurements of the microfluidic system capacitance and the microdroplet contact
angle.
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Stand-off detection of hazardous materials ensures that the responder is located at a safe distance from the suspected
source. Remote detection and identification of hazardous materials can be accomplished using a highly sensitive and
portable device, at significant distances downwind from the source or the threat. Optical sensing methods, in particular
infrared absorption spectroscopy combined with quantum cascade lasers (QCLs), are highly suited for the detection of
chemical substances since they enable rapid detection and are amenable for autonomous operation in a compact and
rugged package. This talk will discuss the sensor systems developed at Pacific Northwest National Laboratory and will
discuss the progress to reduce the size and power while maintaining sensitivity to enable stand-off detection of multiple
chemicals.
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Avoiding or minimizing potential damage from improvised explosive devices (IEDs) such as suicide, roadside, or
vehicle bombs requires that the explosive device be detected and neutralized outside its effective blast radius. Only a few
seconds may be available to both identify the device as hazardous and implement a response. As discussed in a study by
the National Research Council, current technology is still far from capable of meeting these objectives. Conventional
nitrocarbon explosive chemicals have very low vapor pressures, and any vapors are easily dispersed in air. Many pointdetection
approaches rely on collecting trace solid residues from dust particles or surfaces. Practical approaches for
standoff detection are yet to be developed. For the past 5 years, SRI International has been working toward development
of a novel scheme for standoff detection of explosive chemicals that uses infrared (IR) laser evaporation of surfacebound
explosive followed by ultraviolet (UV) laser photofragmentation of the explosive chemical vapor, and then UV
laser-induced fluorescence (LIF) of nitric oxide. This method offers the potential of long standoff range (up to 100 m or
more), high sensitivity (vaporized solid), simplicity (no spectrometer or library of reference spectra), and selectivity
(only nitrocompounds).
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Fielded surface detection systems rely on contact with either the liquid contamination itself or the associated chemical
vapor above the contaminated surface and do not provide a standoff or remote detection capability. Conversely, standoff
chemical vapor sensing techniques have not shown efficacy in detecting those contaminants as liquids or solids on
surfaces. There are a number of optical or spectroscopic techniques that could be applied to this problem of standoff
chemical detection on surfaces. The three techniques that have received the most interest and development are laser
induced breakdown spectroscopy (LIBS), fluorescence, and Raman spectroscopy. Details will be presented on the
development of these techniques and their applicability to detecting CBRNE contamination on surfaces.
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With quality factors (Q) often-exceeding 10,000, vibrating micromechanical resonators have emerged as leading
candidates for on-chip versions of high-Q resonators used in wireless communications systems. However, as in the case
for transistors, extending the frequency of MEMS resonators generally entails scaling of resonator dimensions.
Unfortunately, smaller size often coincides with lower-power handling capability and increased motional impedance. In
this paper we introduce novel transduction techniques which can improve the motional impedance of MEMS resonators
by 1000× over traditional 'air-gap' transduced resonators, present latest results on narrow-bandwidth parametric filters
for frequency-agile radio receivers, and discuss performance scaling of NEMS resonators to X-band frequencies.
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Miniaturization of mass-based resonant sensors is a promising strategy for chemical detection due to the increased
sensitivity afforded by decreased length scales. However, while the increased surface area-to-volume ratios of microand
nano-scale devices provide sensitivity benefits, smaller scales pose additional challenges in fabrication. We
introduce the use of porous silicon resonators to provide increased sensitivity in resonant vapor sensors with minimal
fabrication challenge. Standard top-down processes were used to fabricate micrometer-scale resonators with nanometerscale
pores. The increased surface area of the porous resonating structures improved their detection sensitivity, and the
porous nature of the resonator itself eliminated the need to apply porous coatings separate from the resonator. At present,
porous silicon resonators show up to 100% sensitivity enhancement to isopropyl alcohol (vapor) over non-porous silicon
resonators. Ongoing work involves investigating the limits of porosity and therefore sensitivity, the tradeoff between
porosity and mechanical robustness, and the physics of resonant porous materials.
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Graphene represents an important new material with potential Department of Defense sensor applications. At the Naval
Research Laboratory we have developed three techniques to produce large-area graphene films. We have used this
material to construct chemical and radio-frequency electromagnetic sensors. Here we report the initial results of this
effort.
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RF system front ends need to be mounted on a circuit board and interconnected to other devices such
as antennas and surrounding circuitry functions. Providing suitable RF performing interconnects
between or within devices on multi-layer construction has been done typically with doped
semiconductors, copper, and occasionally other conductors. This paper discusses the use of organic
printed circuit board MEMS switches and varactors, and the use of multi-wall carbon nanotubes as
transmission lines and antennas. Carbon nanotube active transistors use single wall carbon nanotubes
(SWCNT) with efforts to improve percentages of semiconducting structures. Interconnects are
needed not only to connect CNT devices to each other, but to larger structures in order to be able to
use subsystems that integrate CNT devices, large scale multifunction ICs, and RF devices used in RF
front ends, including antennas. This paper addresses the use of organic substrates as the media for
integration of MEMS, interconnects to devices on the substrate, and planar antennas. These methods
will be required until complete assembly of all devices and interconnects can be done with processes
at the nano-scale level, which is assumed to still need efficient radiative antenna structures at a larger
scale for commonly used consumer wireless products.
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We provide an overview of our work where carbon-based nanostructures have been applied to twodimensional
(2D) planar and three-dimensional (3D) vertically-oriented nano-electro-mechanical (NEM)
switches. In the first configuration, laterally oriented single-walled nanotubes (SWNTs) synthesized using
thermal chemical vapor deposition (CVD) were implemented for forming bridge-type 2D NEMS switches,
where switching voltages were on the order of a few volts. In the second configuration, vertically oriented
carbon nanofibers (CNFs) synthesized using plasma-enhanced (PE) CVD have been explored for their
potential application in 3D NEMS. We have performed nanomechanical measurements on such vertically
oriented tubes using nanoindentation to determine the mechanical properties of the CNFs. Electrostatic
switching was demonstrated in the CNFs synthesized on refractory metallic nitride substrates, where a
nanoprobe was used as the actuating electrode inside a scanning-electron-microscope. The switching voltages
were determined to be in the tens of volts range and van der Waals interactions at these length scales appeared
significant, suggesting such structures are promising for nonvolatile memory applications. A finite element
model was also developed to determine a theoretical pull-in voltage which was compared to experimental
results.
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Enzymes are commonly used as the active element in chemical sensors because of their analyte specificity, sensitivity,
and the speed with which they catalyze reactions. Their precision and reliability has them at the core of many FDAapproved
medical diagnostic tests. Unfortunately, nature has evolved most enzymes to operate under a fairly narrow
range of storage and operating conditions (i.e. pH, ionic strength, temperature, organic content, etc). The deployment of
enzyme-based sensors in poorly controlled environments with fluctuating conditions can therefore be difficult.
ICx Technologies has sought to minimize the impact of environmental parameters on enzyme catalysis through enzyme
polymerization. Rather than being simply immobilized onto an existing substrate, enzymes are used as co-monomers
with other conventional monomers in polymerization reactions. Enzymes are incorporated within the polymer through
multiple covalent attachments. By essentially anchoring the enzyme's tertiary structure, the polymerization process
reduces enzyme sensitivity to many environmental factors. ICx has built a number of chemical sensors using enzyme
polymers, some of which continuously monitor air or water in real time. The developed sensors have proven to operate
well in many different environments.
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A promising sensing technology utilizing AlGaN/GaN high electron mobility transistors (HEMTs) has been
developed to analyze a wide variety of environmental and biological gases and liquids. The conducting 2DEG channel
of GaN/AlGaN HEMTs is very close to the surface and extremely sensitive to adsorption of analytes. Examples of
detecting mercury ions, perkinsus, lactic acid, carbon dioxide, and vitellogenin are discussed in this paper.
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This paper presents a robust sensor to detect low concentration (<1 ppm) of CO gas. The
sensor is based on AlGaN/GaN Metal-Oxide-Semiconductor High Electron Mobility
Transistor (MOS-HEMT) with a non-conventional gate structure. The performance of the
device has been simulated based on the charge control physics of AlGaN/GaN heterostructure
transistor. Large sensitivities and widely linear characteristics are obtained for the
AlGaN/GaN device based sensor assuming ideal gas-surface kinetics which can be
approximated by the proposed gate structure. The sensor generates 0.8 μA of current for 0.5
ppm concentration of CO. The sensor shows linear characteristics for concentration of 1000
ppm CO. The effects of varying aspect ratio on total changes in current, sensitivity and
linearity of the device have been simulated.
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Aerospace applications require a range of chemical sensing technologies to monitor conditions related to both space
exploration and aeronautic aircraft operations. These applications include leak detection, engine emissions monitoring,
fire detection, human health monitoring, and environmental monitoring. This paper discusses efforts to produce
microsensor platforms and Smart Sensor Systems that can be tailored to measure a range of chemical species. This
technology development ranges from development of base sensor platforms to the evaluation of more mature systems in
relevant environments. Although microsensor systems can have a significant impact on aerospace applications, extensive
application testing is necessary for their long-term implementation. The introduction of nanomaterials into microsensor
platforms has the potential to significantly enable improved sensor performance, but control of those nanostructures is
necessary in order to achieve maximum benefits. Examples will be given of microsensor platform technology, Smart
Sensor Systems, application testing, and efforts to integrate and control nanostructures into sensor structures.
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Silicon Carbide (SiC) is a wide bandgap semiconductor with outstanding physical properties for manufacturing detectors
of ionizing radiation (alpha, electrons, protons, X and gamma rays). The wide band gap (up to 3.2 eV), high saturation
velocities of the charge carriers (2x107 cm/s), high breakdown field (2 MV/cm), high thermal conductivity (4.9 W/cm2)
and its radiation hardness, allow low-noise and reliable operation in environments which are critical or forbidden to other
semiconductor detectors. In the last ten years, considerable R&D efforts have been devoted worldwide to growth and
process technologies which have made available high purity epitaxial 2'' and 3'' SiC wafers. The state of the art of SiC
micro-detector manufacturing technology will be presented together with prototype detectors with high resolution
spectroscopic capabilities and outstanding low noise performance at room and high temperatures. The experimental
characterization of different detector types (pad, pixel and microstrip) is shown and the radiation hardness of SiC
detectors is discussed. X-ray spectroscopy with SiC will be presented: intrinsic line widths of 232 eV FWHM at +29°C
and 336 eV FWHM at +100°C have been obtained using a SiC microstrip detector with 32 strips, 2 mm long and 25 μm,
the recorded performance being fully limited by the noise of the front-end electronics. The necessity and the limits of
ultimate low-noise front-end for reading out the Fano-limited SiC detectors are discussed.
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We develop novel GaN-based high temperature and radiation-hard electronics to realize data acquisition electronics and
transmitters suitable for operations in harsh planetary environments. In this paper, we discuss our research on
AlGaN/GaN metal-oxide-semiconductor (MOS) transistors that are targeted for 500 °C operation and >2 Mrad radiation
hardness. For the target device performance, we develop Schottky-free AlGaN/GaN MOS transistors, where a gate
electrode is processed in a MOS layout using an Al2O3 gate dielectric layer. The AlGaN/GaN MOS transistors fabricated
with the wide-bandgap gate oxide layer enable Schottky-free gate electrodes, resulting in a much reduced gate leakage
current and an improved sub-threshold current than the current AlGaN/GaN field effect transistors. In this study,
characterization of our AlGaN/GaN MOS transistors is carried out over the temperature range of 25°C to 500°C. The Ids-
Vgs and Ids-Vds curves measured as a function of temperature show an excellent pinch-off behavior up to 450°C. Off-state
degradation is not observed up to 400 °C, but it becomes measurable at 450 °C. The off-state current is increased at 500
°C due to the gate leakage current, and the AlGaN/GaN MOS HEMT does not get pinched-off completely. Radiation
hardness testing of the AlGaN/GaN MOS transistors is performed using a 50 MeV 60Co gamma source to explore effects
of TID (total ion dose). Excellent Ids-Vgs and Ids-Vds characteristics are measured even after exposures to a TID of 2Mrad.
A slight decrease of saturation current (ΔIdss~3 mA/mm) is observed due to the 2Mrad irradiation.
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Brian Morgan, Sarah Bedair, Jeffrey S. Pulskamp, Ronald G. Polcawich, Christopher Meyer, Christopher Dougherty, Xue Lin, David Arnold, Rizwan Bashirullah, et al.
Scaling down autonomous robotic systems introduces numerous challenges in mechanical design, electrical/sensor
subsystems, and autonomous control. One particularly daunting task is the design of the power system, since this will
ultimately limit all microrobot or micro-UAV's operations. Power sources like lithium polymer batteries possess
sufficient power density for basic mobility (walking, fixed wing flight, flapping/hovering), but improved power sources
are needed that offer increased energy density in order to extend mission lifetimes - preferably pushing from minutes to
multiple hours or days. Additionally, the source power must be efficiently converted and distributed to the various
microrobot subsystems. Each system may require a different voltage, current, and duty cycle. This paper will review
some of the power-specific challenges related to developing small, mobile autonomous systems.
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This paper explores the recent advances in circuit structures and design methodologies that have enabled ultra-low power
sensing platforms and opened up a host of new applications. Central to this theme is the development of Near Threshold
Computing (NTC) as a viable design space for low power sensing platforms. In this paradigm, the system's supply
voltage is approximately equal to the threshold voltage of its transistors. Operating in this "near-threshold" region
provides much of the energy savings previously demonstrated for subthreshold operation while offering more favorable
performance and variability characteristics. This makes NTC applicable to a broad range of power-constrained
computing segments including energy constrained sensing platforms. This paper explores the barriers to the adoption of
NTC and describes current work aimed at overcoming these obstacles in the circuit design space.
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This paper presents a discussion on sizing, weight and power of micro autonomous air and ground vehicles. While
the air vehicles include both rotor and flapper based design, here the focus is on rotor based designs. The paper
presents modeling methodologies for initial sizing of these vehicles and a survey of small COTS batteries. Some
results from initial iterations on sizing vehicles and payloads are also presented. For air-vehicles, several factors
have been identified in the sizing process, which can be adjusted in the search for a feasible design. These factors
include the rotor figure of merit, the motor efficiency, and the battery specific energy. For ground vehicles, due
to limited experimental data, three different ways for preliminary estimation of power requirements as a function
of vehicle mass have been explored here. The sizing methodologies marry theoretical foundations with empirical
observations and estimations.
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Insensitivity to edge recombination is observed in GaAs-based InAs/InGaAs quantum dots-in-a-well (DWELL) solar
cells by comparing their current-voltage (IV) plot to GaAs control samples. The edge recombination current component
is extracted by analyzing devices of different areas and then compared to DWELL cells of comparable dimensions. The
results demonstrate that GaAs-based solar cells incorporating a DWELL design are relatively insensitive to edge
recombination by suppressing lateral diffusion of carriers in the intrinsic layer, and thus promising for applications that
require small area devices such as concentration or flexible surfaces. Preliminary studies on the integration of these cells
onto flexible surfaces such as Kapton and nanopaper are discussed including weight considerations for all the integrated
materials.
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The design of robots able to locomote effectively over a diversity of terrain requires detailed ground interaction
models; unfortunately such models are lacking due to the complicated response of real world substrates which can
yield and flow in response to loading. To advance our understanding of the relevant modeling and design issues,
we conduct a comparative study of the performance of DASH and RoACH, two small, biologically inspired,
six legged, lightweight (~10 cm, ~20 g) robots fabricated using the smart composite microstructure (SCM)
process. We systematically examine performance of both robots on rigid and flowing substrates. Varying both
ground properties and limb stride frequency, we investigate average speed, mean mechanical power and cost
of transport, and stability. We find that robot performance and stability is sensitive to the physics of ground
interaction: on hard ground kinetic energy must be managed to prevent yaw, pitch, and roll instability to
maintain high performance, while on sand the fluidizing interaction leads to increased cost of transport and
lower running speeds. We also observe that the characteristic limb morphology and kinematics of each robot
result in distinct differences in their abilities to traverse different terrains. Our systematic studies are the first
step toward developing models of interaction of limbs with complex terrain as well as developing improved limb
morphologies and control strategies.
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Micro Air Vehicles (MAVs) operate with many inter-related constraints, including size, weight, power, processing, and
communications bandwidth. Basic equations can be used to provide initial estimates of subsystem parameters that are
consistent with the targeted size and related parameters. For most current MAVs, the power source of choice is
batteries, and the choice of battery type and size will determine the maximum duration of a flight. In this study, first
order models for both rotary wing MAVs and crawling ground platforms are used to determine the optimum battery size
for maximum endurance, given typical parameter values for a 15-cm scale robotic platform. Results indicate that most
micro robotic platforms use battery sizes significantly different than optimum.
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As part of our research for the ARL MAST CTA (Collaborative Technology Alliance) [1], we present an integrated
architecture that facilitates the design of microautonomous robot platforms and missions, starting from initial design
conception to actual deployment. The framework consists of four major components: design tools, mission-specification
system (MissionLab), case-based reasoning system (CBR Expert), and a simulation environment (USARSim). The
designer begins by using design tools to generate a space of missions, taking broad mission-specific objectives into
account. For example, in a multi-robot reconnaissance task, the parameters varied include the number of robots used,
mobility capabilities (e.g. maximum speeds), and sensor capabilities. The design tools are used to intelligently carve out
the space of all possible parameter combinations to produce a smaller set of mission configurations. Quantitative
assessment of this design space is then performed in simulation to determine which particular configuration would yield
an effective team before actual deployment. MissionLab, a mission-specification platform, is used to incorporate the
input parameters, generate the underlying robot missions, and control the robots in simulation. It also provides logging
mechanisms to measure a range of quantitative performance metrics, such as mission completion rates, resource
utilization, and time to completion, which are then used to determine the best configuration for a particular mission.
These metrics can also provide guidance for the refinement of the entire design process. Finally, a case-based reasoning
system allows users to maximize successful deployment of the robots by retrieving proven configurations and determine
the robot capabilities necessary for success in a particular mission.
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In today's world, consumer driven technology wants more portable electronic gadgets to be developed, and the next big
thing in line is self-powered handheld devices. Therefore to reduce the power consumption as well as to supply sufficient
power to run those devices, several critical technical challenges need to be overcome:
a. Nanofabrication of macro/micro systems which incorporates the direct benefit of light weight (thus portability), low
power consumption, faster response, higher sensitivity and batch production (low cost).
b. Integration of advanced nano-materials to meet the performance/cost benefit trend. Nano-materials may offer new
functionalities that were previously underutilized in the macro/micro dimension.
c. Energy efficiency to reduce power consumption and to supply enough power to meet that low power demand.
We present a pragmatic perspective on a self-powered integrated System on Chip (SoC). We envision the integrated
device will have two objectives: low power consumption/dissipation and on-chip power generation for implementation
into handheld or remote technologies for defense, space, harsh environments and medical applications. This paper
provides insight on materials choices, intelligent circuit design, and CMOS compatible integration.
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We use fiber-paper-supported carbon nanofoams as the basis for "multifunctional electrode nanoarchitectures" in which
the nanofoams serve as conductive, ultraporous scaffoldings for subsequent incorporation of electroactive functionalities
such as metal oxides, metal nanoparticles, and ultrathin polymers. The resulting functionalized carbon nanofoam papers
are designed to serve as "plug-and-play" electrode structures in electrochemical devices ranging from high-rate Li-ion
batteries and electrochemical capacitors to metal-air batteries and fuel cells. Electroless deposition is an attractive
approach to functionalize structurally complex substrates, such as carbon nanofoams, and we have recently demonstrated
that conformal nanoscopic coatings of manganese oxide (MnOx) can be generated on the exterior and interior surfaces of
pre-formed carbon nanofoam papers via redox reaction with aqueous permanganate (MnO4-). The resulting nanoscale
MnOx coatings provide not only faradaic charge-storage functionality to the nanofoam structure, but also enhanced
electrocatalytic activity for molecular oxygen reduction. The electrocatalytic functionality of MnOx can now be
combined with the desirable structural characteristics of carbon nanofoams (through-connected and size-tunable pore
structures, high specific surface areas, and good electrical conductivity) to produce high-performance air-breathing
cathodes for metal-air batteries. Herein, we report preliminary results for a particular series of native and
MnOx-functionalized carbon nanofoams as examined for their O2-reduction activity in a three-electrode testing
configuration.
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Pathways to scaling up the power and voltage output of on-chip micro-solid oxide fuel cells (μSOFC) have been
investigated. μSOFC arrays consisting of one thousand three hundred and thirty-two (1332) membranes have been
lithographically fabricated on 4" wafers. The membranes, with widths of ~150 μm, are comprised of 15-nm-thick
La0.6Sr0.4Co0.8F0.2O3 (LSCF) or 100-nm-thick porous Pt cathodes, 75-nm-thick Y0.15Z0.85O1.93 (YSZ) electrolytes, and
100-nm-thick porous Pt anodes. Yield of fabrication is greater than 99% and only a few membranes failed after
annealing at 500 °C. However, to reduce resistive loss, a current collector or a much thicker LSCF needs to be
implemented if using LSCF as the cathode material on 4" wafers. Prototype components of μSOFC stacks for scaling up
output voltage are also presented. The stacks require only two components - namely, a μSOFC plate and a bipolar
separator - to form a repeating unit for the stacks. Flow channels and through silicon vias are integrated in the
components. Challenges in fabrication and direction for further improvement for these approaches are discussed. The
preliminary results suggest potential for further exploration into wafer-scale processing of fuel cell device structures for
portable energy.
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1D Nanostructure-Based Chemical and Biological Sensors I
One-dimensional nanostructures have attracted considerable interest as potential building blocks and functional
components in next generation nanoscale sensing, nanoelectromechanical systems (NEMS), circuits, and interconnect
applications. The integration and assembly of one-dimensional nanostructures into such device architectures remains a
significant challenge. Techniques for site-specific synthesis and self-assembly of one-dimensional nanostructures have
proved suitable for a range of integrated nanostructure based-sensing applications yielding robust sensing capabilities
realized with a streamlined fabrication process. Specifically, localized heating has emerged as a viable technique for the
site specific synthesis of one-dimensional nanostructures. By localizing the heat source, the extent of chemical vapor
deposition synthesis reactions can be confined to well-defined, microscale regions. Using the localized synthesis and
self-assembly approach, proof-of-concept gas and pressure sensing applications have been demonstrated. The integration
and self-assembly approach and sensing applications are described.
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1D Nanostructure-Based Chemical and Biological Sensors II
Electron tunneling between nanospaced electrodes provides a mechanism for directly transducing the presence of
molecular analytes into electrical signals. Crossbar junctions with vertical separations on the order of a few nanometers
were fabricated using a combination of electron-beam lithography and selective chemical etching. The current-voltage
properties of the nanojunctions are highly sensitive to the chemical environment. The tunneling currents increase over
one order of magnitude in response to water and organic vapors diluted with a background of pure nitrogen. The
resistance of the junctions is also dependent on the concentration of the analyte. These results demonstrate that
tunneling can be used to detect changes in the chemical environment.
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We demonstrate anomalous gaseous field ionization and field desorption on branching intrinsic silicon nanowires
grown by a two-step VLS technique. Field ionization and desorption I-V curves of argon, nitrogen, helium, and
ammonia, were recorded individually within a wide pressure range (10-7 to 10 Torr). Field ionization initiated at sub
volt was followed by field desorption at about 7 - 38 V (applied field of ~ 7×102 to 3.8×103 V/cm). Such voltages
are three orders of magnitude smaller than the applied voltages required to generate field ionization on sharp
metallic tips having the same tip curvature. The measured I-V curves were pressure dependent. Low voltage filed
ionization and desorption phenomena were attributed to the combination effects of geometrical field enhancement
on the apex of nanoscale silicon branches, field penetration, increased tunneling critical distance, band gap widening
due to quantum confinement, and the surface states formed by the catalyst. The results presented herein suggest that
gold terminated branching silicon nanowires could be strong candidates in building low power gas ionization
sensors useful in highly selective detection of gases with low adsorption energies.
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Integrated Nanomaterials, Devices, and Systems for Energy Applications
Thermoelectrics have been investigated for their cooling and energy harvesting uses over the last
six decades. Those devices can be bought from a number of commercial suppliers.
Thermotunneling (TT) devices, on the other hand, have been known only for the last two decades,
and nobody has been able to practically manufacture or demonstrate the performance of those
devices. In this study, we will discuss the high thermodynamic efficiency of these systems and
design bottlenecks to reach the high efficiencies such as thermal back path and electrical losses.
Concepts for possible device designs will be discussed in detail. Efficiency of those devices will
be compared with the conventional power generation as well as solid-state power generation
systems. Thermodynamic limits of TT systems will be compared, and first order economic
analysis will be performed.
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With the miniaturization of portable electronic devices, there is a demand for micro-power source which can be
integrated on the semiconductor chips. Various micro-batteries have been developed in recent years to generate or store
the energy that is needed by microsystems. Micro-supercapacitors are also developed recently to couple with microbatteries
and energy harvesting microsystems and provide the peak power. Increasing the capacity per footprint area of
micro-batteries and micro-supercapacitors is a great challenge. One promising route is the manufacturing of three
dimensional (3D) structures for these micro-devices. In this paper, the recent advances in fabrication of 3D structure for
micro-batteries and micro-supercapacitors are briefly reviewed.
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The development of next-generation energy resources that are reliable and economically/environmentally acceptable is a
key to harnessing and providing the resources essential for the life of mankind. Our research focuses on the development
of novel semiconductor platforms that would significantly benefit energy harvesting, in particular, from light and heat. In
these critical applications, traditional semiconductor solid-state devices, such as photovoltaic (PV) and thermoelectric
(TE) devices based on a stack of single-crystal semiconductor thin films or single-crystal bulk semiconductor have
several drawbacks, for instance; scalability-limits arise when ultra-large-scale implementation is envisioned for PV
devices and performance-limits arise for TE devices in which the interplay of both electronic and phonon systems is
important. In our research, various types of nanometer-scale semiconductor structures (e.g., nanowires and
nanoparticles) coupled to or embedded within a micrometer-scale semiconductor structure (i.e., semiconductor nanomicrometer
hybrid platforms) are explored to build a variety of non-conventional PV and TE devices. Two core projects
are to develop semiconductor nano-micrometer hybrid platforms based on (1) an ensemble of single-crystal
semiconductor nanowires connected to non-single-crystal semiconductor surfaces and (2) semimetallic nanoparticles
embedded within a single-crystal semiconductor. The semiconductor nano-micrometer hybrid platforms are studied
within the context of their basic electronic, optical, and thermal properties, which will be further assessed and validated
by comparison with theoretical approaches to draw comprehensive pictures of physicochemical properties of these
semiconductor platforms.
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Energy is the ultimate currency that drives the world economy. Without energy, the global economy would
cease to function normally. Most of the world's energy comes from the burning of fossil fuels such as coal
and oil. Unfortunately, these fossil fuels are limited and pollute the atmosphere. The rising costs and demand
of energy products and the alarming rate of global warming have focused research efforts into alternative
forms of renewable energy. Thermoelectrics are one class of renewable energy producing devices.
Thermoelectrics operate by converting temperature differences into electrical power and vice versa. They
find limited use due to their low efficiencies and high cost. This article will review the operation of
thermoelectrics and their current state-of-the-art. It will also explore future promising research endeavors that
aim to increase their efficiency.
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This paper reports cantilever-type nano-electro-mechanical systems (NEMS) silicon carbide (SiC) switches capable of
operation from 25°C to 600°C, with threshold voltages ≤5 V. The fabricated SiC switches are actuated electrostatically,
wherein the suspended cantilever electrode is pulled down to contact the bottom stationary electrode. The switches,
fabricated using surface micromachining, have electrode separation gaps determined by the ~75 nm-thick sacrificial
SiO2. Two-terminal switches have been cycled more than 40 billion times at room temperature until failure and more
than 2 million times at 600°C when the package wire bonds fail. The room temperature failure mechanisms of these
switches are mechanical fracture and stiction. Stiction of the switch electrodes is strongly correlated to the roughness of
their contacting surfaces. Measurements indicate that 60% of switches with 8 nm electrode surface roughness could be
operated over billions cycles before fracture. In contrast, 85% of the switches with 1 nm roughness were stuck after
fabrication release.
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Most current capacitive RF-MEMS switch technology is based on conventional dielectric materials such as SiO2 and
Si3N4. However, they suffer not only from charging problems but also stiction problems leading to premature failure of
an RF-MEMS switch. Ultrananocrystalline diamond (UNCD(R) (2-5 nm grains) and nanocrystalline diamond (NCD) (10-
100 nm grains) films exhibit one of the highest Young's modulus (~ 980-1100 GPa) and demonstrated MEMS resonators
with the highest quality factor (Q ≥10,000 in air for NCD) today, they also exhibit the lowest force of adhesion among
MEMS/NEMS materials (~10 mJ/m2-close to van der Waals' attractive force for UNCD) demonstrated today. Finally,
UNCD exhibits dielectric properties (fast discharge) superior to those of Si and SiO2, as shown in this paper. Thus,
UNCD and NCD films provide promising platform materials beyond Si for a new generation of important classes of
high-performance MEMS/NEMS devices.
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A major challenge associated with the demonstration of high frequency and fast NanoElectroMechanical Systems
(NEMS) components is the ability to efficiently transduce the nanomechanical device. This work presents noteworthy
opportunities associated with the scaling of piezoelectric aluminum nitride (AlN) films from the micro to the nano realm
and their application to the making of efficient NEMS resonators and switches that can be directly interfaced with
conventional electronics. Experimental data showing NEMS AlN resonators (250 nm thick with lateral features as small
as 300 nm) vibrating at record-high frequencies approaching 10 GHz with Qs close to 500 are presented. These NEMS
resonators could be employed as sensors to tag analyte concentrations that reach the part per trillion levels or for
frequency synthesis and filtering in ultra-compact microwave transceivers. 100 nm thick AlN films have been used to
fabricate NEMS actuators for mechanical computing applications. Experimental data confirming that bimorph nanopiezo-
actuators have the same piezoelectric properties of microscale counterparts and can be adopted for the
implementation of mechanical logic elements are presented.
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Carbon materials, including carbon nanotubes and nanostructured diamond, have been investigated for over a decade for
application to electron field emission devices. In particular, they have been investigated because of their low power
consumption, potential for miniaturization, and robustness as field emission materials, all properties that make
nanocarbon materials strong candidates for applications as long life electron sources for mass spectrometers for space
exploration, where electron sources are exposed to harsh environments, .A miniaturized mass spectrometer under
development for in situ chemical analysis on the moon and other planetary environments requires a robust, long-lived
electron source, to generate ions from gaseous sample using electron impact ionization. To this end, we have explored
the field emission properties and lifetime of nitrogen-incorporated ultrananocrystalline diamond films. We will present
recent results revealing that UNCD films with nitrogen incorporation during growth (N-UNCD) yield stable/high fieldinduced
electron emission in high vacuum for up to 1000 hours.
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Having recently been demonstrated at frequencies over 1GHz with measured Q's>10,0001-6, MEMS/NEMS resonators
in silicon, SiC and CVD diamond structural materials have great potential for enabling resonant mass sensing down to
zeptogram resolution as well as on-chip high-Q passives needed in wireless communication systems for frequency
generation, translation and filtering. However, the acceptance of such devices for RF applications in present-day
transceivers has been hindered so far by several remaining issues, including: (1) a frequency range lower than 5 GHz, (2)
higher motional impedances than normally exhibited by macroscopic high-Q resonators, (3) limited linearity and power
handling ability, and (4) insufficient frequency repeatability and stability. This paper reviews several material-centric
strategies for alleviating the aforementioned issues. Given that resonance frequency is generally proportional to the
acoustic velocity while energy dissipation and Q is also a strong function of the material properties, several deviceoriented
and system-level performance-enhancing technologies will be discussed. Both capacitively-transduced and
piezoelectrically-transduced resonators will be discussed with a particular emphasis on the employment of transducers
with improved electromechanical coupling coefficient as the device-level method for lowering the motional impedance.
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We present the design, fabrication, and characterization of a pixelated, hyperspectral arrayed component for Focal
Plane Array (FPA) integration in the Long-Wave IR. This device contains tens of pixels within a single super-pixel
which is tiled across the extent of the FPA. Each spectral pixel maps to a single FPA pixel with a spectral FWHM
of 200nm. With this arrayed approach, remote sensing data may be accumulated with a non-scanning, "snapshot"
imaging system.
This technology is flexible with respect to individual pixel center wavelength and to pixel position within the array.
Moreover, the entire pixel area has a single wavelength response, not the integrated linear response of a graded
cavity thickness design. These requirements bar tilted, linear array technologies where the cavity length
monotonically increases across the device.
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EO/IR Sensors and imagers using nanostructure based materials are being developed for a variety
of Defense Applications. In this paper, we will discuss recent modeling effort and the
experimental work under way for development of next generation carbon nanostructure based
infrared detectors and arrays. We will discuss detector concepts that will provide next generation
high performance, high frame rate, and uncooled nano-bolometer for MWIR and LWIR bands.
The critical technologies being developed include carbon nanostructure growth, characterization,
optical and electronic properties that show the feasibility for IR detection. Experimental results on
CNT nanostructures will be presented. We will discuss the path forward to demonstrate
enhanced IR sensitivity and larger arrays.
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Optical transport in planar waveguide structures is of great importance for spectroscopic chemical and biological sensing
applications. We have fabricated a TiO2-polymer planar waveguide with an embedded grating coupler. The grating
coupler consists of a low index layer of SiO2 on a Si(100) substrate. The SiO2 layer has a grating pattern reactive ion
etched into the surface. On top of this surface is a high index TiO2 waveguide. The TiO2 film is generated from a spincoated
polymer solution, OptiNDEXTM EXP04054 from Brewer Science. The TiO2 film has low optical absorption, a
high refractive index, and good thermal and UV stability. It is possible to make up to a 420nm film in a single coating
operation. To form the TiO2 film the polymer solution is spin-coated onto a wafer and the wafer is baked at 300 °C for 10
minutes. Scanning electron microscopy and focused ion beam cross-sections verified that the TiO2 conformally fills the
groves of the grating. We made electrodynamic calculations based on the indices of the materials for our waveguiding
structure and the wavelength of the incident light for single-mode wave guiding. These calculations gave a projected
TiO2 thickness for our waveguides. Experimental results show that the waveguide structures that we fabricated were in
close agreement with these predictions.
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We present a system for secure identification applications that is based upon biometric-like MEMS chips. The
MEMS chips have unique frequency signatures resulting from fabrication process variations. The MEMS chips possess
something analogous to a "voiceprint". The chips are vacuum encapsulated, rugged, and suitable for low-cost, highvolume
mass production. Furthermore, the fabrication process is fully integrated with standard CMOS fabrication
methods.
One is able to operate the MEMS-based identification system similarly to a conventional RFID system: the
reader (essentially a custom network analyzer) detects the power reflected across a frequency spectrum from a MEMS
chip in its vicinity. We demonstrate prototype "tags" - MEMS chips placed on a credit card-like substrate - to show how
the system could be used in standard identification or authentication applications. We have integrated power scavenging
to provide DC bias for the MEMS chips through the use of a 915 MHz source in the reader and a RF-DC conversion
circuit on the tag.
The system enables a high level of protection against typical RFID hacking attacks. There is no need for signal
encryption, so back-end infrastructure is minimal. We believe this system would make a viable low-cost, high-security
system for a variety of identification and authentication applications.
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Quantum dots (QDs) are fluorescent semiconductor (e.g. II-VI) nanocrystals, which have a strong characteristic
spectral emission. This emission is tunable to a desired energy by selecting variable particle size, size distribution and
composition of the nanocrystals. QDs have recently attracted enormous interest due to their unique photophysical
properties and range of potential applications in photonics and biochemistry. The main aim of our work is develop new
chiral quantum dots (QDs) and establish fundamental principles influencing their structure, properties and biosensing
behaviour. Here we present the synthesis and characterisation of chiral CdSe semiconductor nanoparticles and their
utilisation as new chiral biosensors. Penicillamine stabilised CdSe nanoparticles have shown both very strong and very
broad luminescence spectra. Circular dichroism (CD) spectroscopy studies have revealed that the D- and Lpenicillamine
stabilised CdSe QDs demonstrate circular dichroism and possess almost identical mirror images of CD
signals. Studies of photoluminescence and CD spectra have shown that there is a clear relationship between defect
emission and CD activity. We have also demonstrated that these new QDs can serve as fluorescent nanosensors for
various chiral biomolecules including nucleic acids. These novel nanosensors can be potentially utilized for detection of
various chiral biological and chemical species with the broad range of potential applications.
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Nano and micro-structure electrode gaps were fabricated by an electroforming method. Thin film materials were
fabricated on an insulator substrate and the microelectrodes with desired shapes were fabricated. Then the electroformation
was carried out to produce the gap structure. Controllability of the size of these gaps was investigated by
modeling and experimental method. It was found that the nanostructure of wide range of metal, metal oxides and
compound semiconductors can be fabricated by this method. In this study, we have attempted formation of Al and Au.
Simulation study was carried out based on finite element analysis (FEA) technique. The simulation results were verified
with the experimental data.
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Nanowire ensembles on non-single crystalline substrates are quickly becoming a popular active
material moving towards commercial device production. In this study, ensembles of InP nanowires
were grown by metal-organic chemical vapor deposition on non-single crystalline substrates. The
samples are complicated by the presence of differing lattice types, geometries, crystal orientations
and physical interaction that occurs in samples with high areal densities. The optical properties of
the nanowires were studied by photoluminescence and Raman spectroscopy at various temperatures.
The spectra are interpreted with particular emphasis on the above-mentioned complications.
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The stability of silver nanoparticles on indium tin oxide coated glass substrates under atmospheric condition was
investigated. These nanoparticles were fabricated using electron beam lithography. Energy dispersive spectroscopy
analysis revealed a high concentration of sulfur in the silver nanoparticles exposed to laboratory air for 12 weeks at room
temperature. Morphological changes in the silver nanoparticles were also observed for nanoparticles stored under the
same conditions. In contrast, silver nanoparticles kept in vacuum did not show chemical or morphological changes after
12 weeks. The present work clearly shows the need to consider ambient exposure when using Ag nanoparticles for
sensors.
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Cantilever based sensors are promising miniaturized sensing tools for bio-chemical applications [1]. These micromechanical
sensors can be employed to sense very small amounts of dangerous substances like explosive molecules,
biological threats and hazardous compounds, both in air or liquid environment. In our project we focus on the
development of a new readout system for employing of this sensing technique for detection of explosives like TNT,
RDX and PETN, under the framework of the Xsense project.
At present available optical equipments for cantilever sensing are typically big and bulky, making the in situ employment
of this technology still very hard.
Here we present a novel approach to measure the absorption of masses on the cantilever surfaces by using a light,
compact, portable and high throughput optical device. Our setup is able to measure real time both the deflection of the
beams and their vibrational frequencies, employing the same laser source and the same photodetector.
The optical readout of cantilever-based sensors was re-designed and developed combining the technology of commercial
DVD-ROM readers [2] with polymer based holding substrates structured with UV-lithography or imprint technology.
Cantilever chips are clamped on a predefined holding substrate structured in SU-8 or in Cyclic Olefin Copolymer (COC),
while the DVD-ROM reader is placed 1 mm below the substrate.
The laser beam is collimated and focused on cantilevers with a 0.75 μm spot diameter and the reflected light is then
recorded using an astigmatism-based 4-quadrant photodetector.
The integration of the DVD-ROM reader with the on-substrate holding approach leads to a high throughput flexible
platform with easy auto-alignment and replacement of the cantilevers chips.
With this new on-substrate approach tens of chips can be placed on the Polymer holder and be read sequentially in a very
light and compact device.
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In this paper we demonstrate the potential for novel nanoporous framework materials (NFM) such as metal-organic
frameworks (MOFs) to provide selectivity and sensitivity to a broad range of analytes including explosives, nerve
agents, and volatile organic compounds (VOCs). NFM are highly ordered, crystalline materials with considerable
synthetic flexibility resulting from the presence of both organic and inorganic components within their structure.
Detection of chemical weapons of mass destruction (CWMD), explosives, toxic industrial chemicals (TICs), and volatile
organic compounds (VOCs) using micro-electro-mechanical-systems (MEMS) devices, such as microcantilevers and
surface acoustic wave sensors, requires the use of recognition layers to impart selectivity. Traditional organic polymers
are dense, impeding analyte uptake and slowing sensor response. The nanoporosity and ultrahigh surface areas of NFM
enhance transport into and out of the NFM layer, improving response times, and their ordered structure enables structural
tuning to impart selectivity. Here we describe experiments and modeling aimed at creating NFM layers tailored to the
detection of water vapor, explosives, CWMD, and VOCs, and their integration with the surfaces of MEMS devices.
Force field models show that a high degree of chemical selectivity is feasible. For example, using a suite of MOFs it
should be possible to select for explosives vs. CWMD, VM vs. GA (nerve agents), and anthracene vs. naphthalene
(VOCs). We will also demonstrate the integration of various NFM with the surfaces of MEMS devices and describe
new synthetic methods developed to improve the quality of VFM coatings. Finally, MOF-coated MEMS devices show
how temperature changes can be tuned to improve response times, selectivity, and sensitivity.
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The research presented in this abstract pertains to nanowire-structured magnetic sensors fabricated by pulsed, template
electrodeposition relying on giant magnetoresistance (GMR). System fabrication involves electrodepositing metals with
a DC-biased square wave from a solution of iron-manganese solution into the porous aluminum oxide surface of an
aluminum sheet. The chemical make-up of the resulting 20nm diameter, 500nm length nanowires was 6 at% manganese
and 45 at% iron, which is desirable because the ferromagnetic layers (Fe) should be large in comparison with the nonmagnetic
layers (Mn). The resulting nanowires exhibited a 73% drop in resistance when exposed to an external magnetic
field.
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A micro differential thermal analysis (DTA) system is used for detection of trace explosive particles. The DTA
system consists of two silicon micro chips with integrated heaters and temperature sensors. One chip is used
for reference and one for the measurement sample. The sensor is constructed as a small silicon nitride bridge
incorporating heater elements and a temperature measurement resistor. In this manuscript the DTA system is
described and tested by measuring calorimetric response of DNT (2,4-Dinitrotoluene). The design of the senor is
described and the temperature uniformity investigated using finite element modelings and Raman temperature
measurements. The functionality is tested using two different kinds of explosive deposition techniques and
calorimetric responses are obtained. Under the framework of the Xsense project at the Technical University of
Denmark (DTU) which combines four independent sensing techniques, these micro DNT sensors will be included
in handheld explosives detectors with applications in homeland security and landmine clearance.
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The simultaneous decrease in electronic device form factors yet increase in functionality has motivated a shift in energy
storage design and manufacture to accommodate novel and unconventional materials, new device geometries, and nontraditional
fabrication methods. We are developing a simple, low-cost, solution-based method for integrating custom
energy storage components directly onto a device. A direct write dispenser printing system is used to pattern solutionsbased
materials into multilayer devices. Along with this fabrication method, we discuss the materials design and device
characterization of two printed energy storage devices: a carbon electrochemical microcapacitor and a zinc-metal oxide
microbattery. The two components will be used as a hybrid energy storage system, capable of providing an energy dense
storage buffer while also being able to address high power pulse loads, all within a limited footprint area.
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Synthesis of carbon nanostructures at low temperature range of 600°C by a filament assisted chemical vapor deposition
method was investigated. This system could be used to synthesis carbon nano-tubes, nano-fibers, and nano-helixes by
changing the catalyst materials. The results indicated that the synthesis of these carbon structures with diameter from 20-
500 nm range is possible with the current method. It has been reported that random deposition of carbon helix structured
in CVD of carbon nanotubes. This paper presents details of these experimental procedures.
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Recently evolved THz technology opens up more possibilities for identification and characterization of different
semiconductor crystal-based compounds. Since the THz waveform is essentially a direct manifestation of the crystal
domain structure, the multicycle THz generation methods allow measuring of geometrical parameters of semiconductor
internal structures as well as of dislocations and other structural defects. The above is useful for both characterization
and identification of semiconductor materials. Further, methods of THz characterization of II-VI, III-V as well as tinary
compounds are discussed. Computational techniques are suggested allowing the noise level reduction for the
measurements.
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Methanol is a hydrogen carrier for fuel cells and its chemical transformations are of great current interest. Methanol
oxidation by vanadium oxides is well studied, hence, serves as a good measure for catalytic activity. Arrays of VO2
nanowires grown on r-cut sapphire prove to be unique for the in situ catalytic activity tests. Here, we present size
and morphology dependent activity of Platinum coated single crystalline VO2 nanowires in methanol oxidation
reactions using Grazing Incidence Small Angle X-ray Scattering (GISAXS). Our findings show an unexpected
sintering behavior of Pt at temperatures as low as 200 °C.
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High Q resonators are a critical component of stable, low-noise communication systems, radar, and
precise timing applications such as atomic clocks. In electronic resonators based on Si integrated circuits,
resistive losses increase as a result of the continued reduction in device dimensions, which decreases their Q
values. On the other hand, due to the mechanical construct of bulk acoustic wave (BAW) and surface
acoustic wave (SAW) resonators, such loss mechanisms are absent, enabling higher Q-values for both BAW
and SAW resonators compared to their electronic counterparts.1 The other advantages of mechanical
resonators are their inherently higher radiation tolerance, a factor which makes them attractive for NASA's
extreme environment planetary missions, for example to the Jovian environments where the radiation doses
are at hostile levels.2 Despite these advantages, both BAW and SAW resonators suffer from low resonant
frequencies and they are also physically large which precludes their integration into miniaturized electronic
systems.
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In this article, an explicit formula is derived for determining appropriate number of simulation
runs to estimate the parametric yield or violation probability of VLSI circuits. The formula involves
no approximation and thus offers a rigorous control of the statistical error of estimation. Moreover,
the formula is substantially less conservative than existing methods and hence can be used to avoid
unnecessary computation. The application of the formula is illustrated by the timing analysis of an
n-input NAND gate with a capacitive load.
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EO/IR Nanosensors are being developed for a variety of Defense and Commercial Systems Applications.
These include UV, Visible, NIR, MWIR and LWIR Nanotechnology based Sensors. The conventional
SWIR Sensors use InGaAs based IR Focal Plane Array (FPA) that operate in 1.0-1.8 micron region.
Similarly, MWIR Sensors use InSb or HgCdTe based FPA that is sensitive in 3-5 micron region. More
recently, there is effort underway to evaluate low cost SiGe visible and near infrared band that covers from
0.4 to 1.6 micron.
One of the critical technologies that will enhance the EO/IR sensor performance is the development of high
quality nanostructure based antireflection coating. Prof. Fred Schubert and his group have used the TiO2
and SiO2 graded-index nanowires / nanorods deposited by oblique-angle deposition, and, for the first time,
demonstrated their potential for antireflection coatings by virtually eliminating Fresnel reflection from an
AlN-air interface over the UV band. This was achieved by controlling the refractive index of the TiO2 and
SiO2 nanorod layers, down to a minimum value of n = 1.05, the lowest value so far reported.
In this paper, we will discuss our modeling approach and experimental results for using oblique angle
nanowires growth technique for extending the application for UV, Visible and NIR sensors and their utility
for longer wavelength application.
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The purpose of this work is to show that it is possible to excite selectively different resonant modes of a
MEMS resonator, by simply changing some parameters in the feedback filter of Pulsed Digital Oscillators
(PDOs). Extensive simulation and experimental results are presented showing the goodness of the proposed
approach. An iterative map, contemplating more than one resonance, is also obtained from the equation
governing the motion of a cantilever.
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Metallic Sn-C composites were prepared by using electrospinning and electrostatic spray deposition (ESD). Morphology
of the material prepared by these methods can be controlled by changing the experimental conditions such as the flow
rate, voltage, composition of precursor solutions. Influence of the morphology on the electrochemical performance for
the same composite was studied. Composite fibers prepared by electrospinning and porous films by ESD were
characterized using X ray Diffraction, Transmission Electron Microscopy and Electrochemical characterization. Both the
fibers and the porous composite films showed good performance compared to the tin nanopowder based anodes.
Capacities of 760mAh/g and 686 mAh/g were obtained for Sn@C-hollow carbon nanofibers and Sn-C porous films,
respectively.
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This work introduces a new control method to dynamically mitigate the effects of the parasitic charge injected in
dielectric layers of electrostatic MEMS switches. This method can be used to increase lifetime and reliability of
electrostatically actuated MEMS devices. The method is based on the opposite behaviors exhibited by the dielectric
charging phenomena when voltage stresses of different polarity are applied to a given device. To this effect, a sigmadelta
sensing and actuation scheme has been implemented: device capacitance is periodically sampled and, according to
the value obtained, positive or negative actuation voltages are applied. Preliminary experimental results with two
different MEMS devices that demonstrate the feasibility of this method are introduced and discussed.
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A metal-insulator-metal (MIM) tunneling diode having response time less than a picosecond (10-12 second) is extremely
important for mixers and detectors operating at terahertz and infrared frequencies. One of the key objectives of this work
is to develop fabrication processes which are well-suited for mass production of nanogap MIM tunneling diodes with
junction area in the range of 10-2 μm2 thus enabling the coveted terahertz frequencies due to the greatly reduced junction
capacitance. A contemporary electron beam stepper of such resolution costs tens of millions and is not viable for mass
production. This work employs standard photolithography and atomic layer deposition (ALD) methods, which allow
formation of a micrometer-wide finger in the second metal layer that is separated from the first layer metal electrode by
an ALD-deposited sidewall dielectric spacer, thus forming a nm-thick vertical tunneling junction. The junction area is
defined by the width of the finger and the thickness of the electrode, while the junction thickness is controlled by the
ALD deposited insulating layer. So far, by using a newly developed process, MIM tunneling diode with micron-scale
self-aligned cross-fingers have been successfully demonstrated. Some preliminary DC characterizations have been
carried out, and device characteristics such as responsivity, I-V, and C-V curves are documented. Ongoing research for
modeling of MIM tunneling diode based on measured data and further reduction of the device junction area enabled by
the new process will lead to MIM diode that could detect the infrared and terahertz spectra with greatly enhanced
responsivity.
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New energy harvesting technologies have drawn interest in recent years for both military
and commercial applications. We present complete analysis of a novel device technology
based on nanowire antennas and very high speed rectifiers (collectively called
nanorectenna) to convert infrared and THz electromagnetic radiation into DC power. A
nanowire antenna can receive electromagnetic waves and an integrated rectifier can
convert them into electrical energy. The induced voltage and current distributions of
nanowire antennas for different geometric parameters at various frequencies are
investigated and analyzed. Also, nanowire antenna arrays with different geometries and
distributions are examined. Moreover, novel nanoantennas are proposed for broadband
operation and power conversion. All numerical computations are conducted using Ansoft
HFSS. An incident plane wave was used to excite each device and simulations were carried out
for frequencies between 0 and 200 THz. A voltage is induced in each device and it is
measured in the thin oxide layer. Finally, optimum geometries of nanowires are proposed
in order to maximize the amount of infrared power that is harvested.
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Detection and quantification of very small amounts of biological species become necessary to allow an early detection of
biothreats. Currently, fluorescence detection and colorimetry are the most frequently used techniques. Although very
sensitive, the necessary labelling step of the biotargets can alter their recognition properties and these methods have a
low potential for integration. This explains the constant effort of research on label-free detection methods. Onedimensional
nanostructures, such as silicon nanowires, have emerged as good candidates for ultra-sensitive electrical
detection of biological species. A silicon nanowire can operate as the channel of a field-effect transistor whose
conductance is modulated by the change of charge of its surface due to the binding of biological species.
A top-down fabrication process of silicon nanowire field effect transistors was developed on SOI and the influence of
several physico-chemical parameters such as environmental electrostatic charges, light, buffer salinity and flow rate was
evaluated. A change of the conductance of the Si nanowire according to the pH of the solution was demonstrated. Si
nanowires were also tested as biosensors and allowed us to a better understanding of the involved phenomena.
Complementary measurements are currently under progress.
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We have investigated the feasibility of significantly improving the performance of currently favored uncooled
infrared (IR) detectors based on Si or VOx microbolometers with a new design employing freestanding suspended
network of single-walled carbon nanotubes (SWCNTs). Such networks have high absorption coefficient, high
temperature coefficient of the resistance (TCR) and extremely low thermal mass. This combination of parameters
translates into an uncooled IR detector with high sensitivity and a very fast temporal response. We show estimates
of key parameters for such a device, demonstrate a method to prepare it using suspended SWCNT networks
achieved by selective removal of a sacrificial oxide layer, thereby forming a cavity under the SWCNT network. We
also present TCR and photothermal bolometric response data of this conceptual structure.
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Non-coding DNA comprises the majority of an organism's DNA and has the potential to store massive amounts of
information. We hypothesize that information can be stored into non-coding DNA using a noisy mechanism comprised
of thermally sensitive liposomes as sensors and measuring transport state variable information through DNA release and
binding in response to stimuli. To test our hypothesis, we performed experiments that demonstrated the in situ, de novo
synthesis of information-encoding DNA using natural biomaterials. Our results were compared to a lumped-parameter
model designed to simulate the experiments. We found promising correlation between the DNA sequences generated by
the simulations and those generated experimentally, suggesting that the in situ, de novo synthesized DNA does store
recoverable information by the mechanism proposed.
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Two non-rotating pumping components, a jet ejector and injector, were designed and tested. Two jet ejectors were
designed and tested to induce a suction draft using a supersonic micronozzle. Three-dimensional axisymmetric nozzles
were microfabricated to produce throat diameters of 187 μm and 733 μm with design expansion ratios near 2.5:1. The
motive nozzles achieved design mass flow efficiencies above 95% compared to isentropic calculations. Ethanol vapor
was used to motivate and entrain ambient air. Experimental data indicate that the ejector can produce a sufficient suction
draft to satisfy both microengine mass flow and power off-take requirements to enable its substitution for high speed
microscale pumping turbomachinery. An ethanol vapor driven injector component was designed and tested to pressurize
feed liquid ethanol. The injector was supplied with 2.70 atmosphere ethanol vapor and pumped liquid ethanol up to a
total pressure of 3.02 atmospheres. Dynamic pressure at the exit of the injector was computed by measuring the
displacement of a cantilevered beam placed over the outlet stream. The injector employed a three-dimensional
axisymmetric nozzle with a throat diameter of 733 μm and a three-dimensional converging axisymmetric nozzle. The
experimental data indicate that the injector can pump feed liquid into a pressurized boiler, enabling small scale liquid
pumping without any moving parts. Microscale injectors could enable microscale engines and rockets to satisfy pumping
and feedheating requirements without high speed microscale turbomachinery.
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