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- Front Matter: Volume 6528
- Keynote Lecture
- Nanowire and Nanotube
- Micro/Nano Devices and MEMS
- Applications I
- Nanostructures
- Biosensors and BioMEMS I
- Biosensors and BioMEMS II
- Biosensors and BioMEMS III
- Applications II
- Packaging
- Integrated Nano- and Micro-structures
- Fabrication and Characterization
- Poster Session
Front Matter: Volume 6528
Front Matter: Volume 6528
Show abstract
This PDF file contains the front matter associated with SPIE Proceedings Volume 6528, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.
Keynote Lecture
MEMS-based phased arrays for Army applications
Show abstract
The Army Aviation and Missile Research, Development, and Engineering Center (AMRDEC) initiated a
research and development project several years ago to develop Micro Electro-Mechanical Systems
(MEMS)-based phased arrays to provide rapid beam steering for sensors, optical and Radio Frequency (RF)
missile seekers, and RF communication links. In particular, the joint AMRDEC/Army Research
Laboratory (ARL) project, which leverages low-cost phased array components developed under the
Defense Advanced Research Projects Agency (DARPA) Low Cost Cruise Missile Defense (LCCMD)
project, is developing RF switches, phase shifters, and passive phased sub-arrays to provide a fast scanning
capability for pointing, acquisition, tracking, and data communication; and rugged, optical MEMS-based
phased arrays to be employed in small volume, low-cost Laser Detection and Ranging (LADAR) seekers.
The current status of the project is disclosed in this paper. Critical technical challenges, which include
design and fabrication of the RF switches and phase shifters, design and fabrication of micro lens arrays,
control of beam steering, scanning angular resolution and array losses, are discussed. Our approach to
overcoming the technical barriers and achieving required performance is also discussed. Finally, the
validity of a MEMS technology approach against competing low cost technologies is presented.
Nanowire and Nanotube
Elastic and magneto-elastic modeling of Galfenol nanowires
Show abstract
This paper presents a magneto-elastic model developed by coupling a finite element elastic and magnetic
formulations with an energy based probabilistic magnetostrictive model. Unidirectional coupled model is
presented first for both sensor and actuator applications and then a fully coupled bidirectional model is developed.
The unidirectional sensor model was validated against experimental results for a 1.58 mm diameter and 32.74 mm
long Galfenol cantilever beam. The model was further used to investigate the response of Galfenol nanowire array
that will be used in a nanowire acoustic sensor. Model predictions suggest that differences in the phase of bending
motion of nanowires in an array will not produce a significant effect on the magnetic response of the array. It also
predicts that the response of a single nanowire can be measured by a magnetic sensor with active measurement
area much larger than the nanowire dimensions.
Bio-inspired electric cilia development for biomedical applications: use of ionic electro-active polymer, nanowire arrays, and micro-stereo-lithography
Show abstract
This presentation demonstrates the fabrication of bio-inspired electric cilia structures using
bottom-up hetero-nanowires and ionic electro active polymer on flexible polyimide substrates. In
order to obtain sensing function of fluid velocity in meso-scale vessels and minimally disturb original
flow condition, parallel arrays of "electronic cilium" with the size of few micrometers in length and
few hundreds nanometers in diameter are vertically fabricated on a thin flexible film. For active layers,
ionic electro active polymer has been applied on hetero-structured nanowires, which provide low
Young's modulus and sensitive to bending moment by lateral force in fluid. This research works
include the characterization of electro active polymer fabrication processes on nanowires and their
mechanical properties by atomic force microscopy and electrochemical analysis tools. In addition, a
three-dimensional microfluidic channel fabrication method using micro-stereo-lithography (MSL) is
introduced in this presentation, which is an efficient method to simulate fluid conditions in blood vessels.
Packaging of an iron-gallium (Galfenol) nanowire acoustic sensor
Show abstract
Packaging is a key issue for the effective working of an iron-gallium (Galfenol) nanowire acoustic sensor for underwater
applications. The nanowire acoustic sensor incorporates cilia-like nanowires made of galfenol, a magnetostrictive
material, which responds by changing magnetic flux flowing through it due to bending stress induced by the incoming
acoustic waves. This stress induced change in the magnetic flux density is detected by a GMR sensor. An effective
package should provide a suitably protective environment to these nanowires, while allowing sound waves to reach the
nanowires with a minimum level of attenuation. A bio-inspired MEMS package has been designed, analogous to a
human-ear cochlea for the nanowire acoustic sensor. In this paper, the process sequence for fabrication of the package is
presented. Unlike other microphones, the nanoacoustic sensor has been enclosed in a cavity to allow free movement of
the nanowires in a fluid medium. The package also ensures resisting ingression of sea water and salt ions to prevent the
corrosion of sensor components. The effect of package material on sensor performance was investigated by conducting
experiments on acoustic impedance and attenuation characteristics, and salt water absorption properties. The package
filled with silicone oil and molded with polydimethylsiloxane (PDMS) is observed to outperform other packages at all
frequencies by minimizing attenuation of the acoustic waves.
Autonomous multifunctional nanobrushes-autonomous materials
Show abstract
In this work, taking advantage of carbon nanotubes' small size, and exceptional mechanical, chemical and
electrical properties, we report on a series of nano-synthesis procedures that combine conventional chemical
vapor deposition and selective substrate area growth followed by chemical functionalizations to fabricate
functionalized nano-brushes from aligned carbon nanotube arrays and chemically selective functional
groups. The high aspect ratio and small dimension, mechanical stability and flexibility, surface chemical and
adhesive characteristics of carbon nanotubes provide opportunities to create nano-brushes with selected
chemical functionalities. The nano-brushes are made from aligned multi-walled carbon nanotube bristles
grafted onto long SiC fiber handles in various configurations and functionalized with various chemical
functional groups. These nano-brushes can easily be manipulated physically, either manually or with the aid
of motors. Here, we explain the autonomous characteristics of the functionalized nano-brushes employing
functional chemical groups such that the nano-brush can potentially collect various metal particles, ions, and
contaminants from liquid solutions and the air environment, autonomously. These functionalized multiwalled
carbon nanotube based nano-brushes can work swiftly in both liquid and air environments. With
surface modification and functionalization, the nanotube nano-brushes can potentially become a versatile
nano-devices in many chemical and biological applications, where they can autonomously pick up the
particles they encounter since they can be chemically programmed to function as Autonomous Chemical
Nano Robots (ACNR).
Modeling of carbon nanotube composites for vibration damping
Show abstract
In recent years, it has been found that the composites of carbon nanotubes (CNTs) and epoxy resin could greatly enhance
damping ability while the stiffness is kept at a very high level. In this research, carbon nanotube enhanced epoxy resin is
fabricated. The dynamic properties of the nanotube composites are experimentally studied. Experimental results show
that CNT additive can provide the composite with significant damping without undergoing large shear strain as
compared to the VEMs, and the dynamic stiffness of the nanotube composite could be even higher than that of the pure
epoxy resin. In order to further study the damping mechanism of the CNT composite, models are developed. Composite
unit cell model containing single CNT segment is built by using finite element method (FEM). Models with different
CNT orientations are solved in order to describe the behaviors of the randomly oriented CNTs inside the epoxy matrix.
Composite loss factor is calculated based on average ratio of the unit cell energy loss to the unit cell energy input.
Calculated loss factors under different strain level are compared with experiment results.
Micro/Nano Devices and MEMS
U.S. Army Corrosion Office's storage and quality requirements for military MEMS program
Show abstract
As the Army transforms into a more lethal, lighter and agile force, the technologies that support these
systems must decrease in size while increasing in intelligence. Micro-electromechanical systems (MEMS) are one
such technology that the Army and DOD will rely on heavily to accomplish these objectives. Conditions for
utilization of MEMS by the military are unique. Operational and storage environments for the military are
significantly different than those found in the commercial sector. Issues unique to the military include; high G-forces
during gun launch, extreme temperature and humidity ranges, extended periods of inactivity (20 years plus)
and interaction with explosives and propellants. The military operational environments in which MEMS will be
stored or required to function are extreme and far surpass any commercial operating conditions. Security and
encryption are a must for all MEMS communication, tracking, or data reporting devices employed by the military.
Current and future military applications of MEMS devices include safety and arming devices, fuzing devices,
various guidance systems, sensors/detectors, inertial measurement units, tracking devices, radio frequency devices,
wireless Radio Frequency Identifications (RFIDs) and network systems, GPS's, radar systems, mobile base systems
and information technology. MEMS embedded into these weapons systems will provide the military with new levels
of speed, awareness, lethality, and information dissemination. The system capabilities enhanced by MEMS will
translate directly into tactical and strategic military advantages.
NanoDAC: object deformation measurements for micro and nanotechnology applications
Show abstract
The manufacturing, handling and control of micro and nano scale devices require the quantification of their geometrical
and mechanical properties. While the measurement of geometrical and size data is easily accessible by SFM and SEM
imaging equipment, mechanical characterization is a general problem for these objects. Different kinds of size effects
more often force material property determination directly on micro/nano objects. Therefore, new strategies for material
testing have to be developed. Displacements and their derivatives are two basic properties to be measured during testing
for many mechanical material properties. The authors make use of SFM and high resolution SEM imaging in order to
obtain spatially resolved displacement data over the scan area. Locally applied cross correlation algorithms are utilized
to compute displacement fields and the corresponding first order derivatives. Micrographs are captured subsequently for
different object load states. The established technique and measurement system (nanoDAC) is reviewed briefly. The
authors present different applications of the nanoDAC method establishing the characterization of micro/nano scale
material behaviour. Among the application fields are approaches to measure fracture mechanics criteria from crack
opening displacement (COD) fields, a method of measuring residual stresses in thin membranes and testing techniques
to measure Young's modulus and Poisson's ratios of thin foils and micro wires. The measurement of fracture mechanics
bases on linear elastic fracture mechanics. Measured by AFM, COD fields in the very vicinity of crack tips are used to
extract fracture toughness values. Stress determination on membranes utilizes the unique capability of focused ion beam
(FIB) equipment, which allows concurrent material milling and micrograph capture with high resolution. A Zeiss XBeam
system has been used to mill trenches and holes into membranes of semiconductor structures. Treated that way
stress release fields are determined from SEM micrographs. Taking into consideration reasonable stress hypotheses,
membrane stresses are calculated from the obtained deformation fields. With the presented methods the basis is
provided for an experimental reliability analysis of MEMS/NEMS and nanodevices.
Micro-mold fabrication using cellulose acetate
K. Y. Cho,
H. K. Lim,
Y. Chen,
et al.
Show abstract
Polymer materials offer numerous advantages including flexible, low cost large area displays, lightweight, easy
processing, good compatibility with a variety of substrates, and easy for structural modifications. Recently electro-active
polymers (EAP) have been attractive due to their potential advantages including ease of processing and control,
mechanical flexibility, and economical advantage. Recently electro-active paper (EAPap) was discovered as a smart
material and as an actuating material with ionic and piezoelectric effects. Before cellulose acetate (CA) micro-pattern
fabrication, solvent effect of micro or nano-pore formation was investigated. Since the micropore scatter the visible light,
micropores give negative effect to apply optical device. The solvent mixture of acetone/dimethylacetamide (DMAc)
created large amount of micro or nanopores. The resulting films were not transparent. However, volatile single solvent
(acetone) did not form pores and gave transparent film. The various shapes of photoresist, such as circle and honeycomb
patterns, were fabricated onto the silicon wafer to use as the mold. Cellulose acetate (CA) was poured to the mold and
peeled off from the mold. The resulting pattern exhibited uniform size of the circle or honeycomb shape without defect.
Comparison of techniques for measurement of residual stresses in multilayered micro-electro-mechanical devices
Show abstract
A major concern in the development of microelectromechanical systems (MEMS) is the presence of residual stress.
Residual stress, which is produced during the fabrication of multi-layer thin-film structures, can significantly affect the
performance of micro-scale devices. Though experimental measurement techniques are accurate, actual stress
measurements can vary dramatically from run to run and wafer to wafer. For this reason, the modeling of this stress can
be a challenging task. Past work has often focused on experimental, static techniques for determining residual stress
levels in single-layer and bi-layer structures. In addition, these past studies have concentrated on residual stress
measurements in thin films as they are being deposited and prior to the release of a particular device. In this effort, three
techniques are used for determining residual stress levels in four-layer piezoelectrically driven cantilevers and resonator
structures. The first technique is a static technique that is based on wafer bow measurements and Stoney's formula. The
second technique is a dynamic technique that is based on parameter identification from nonlinear frequency-response
data. The third technique is also a static technique based on parameter identification from static device deflection
measurements. The devices studied, which are piezoelectric devices, are fabricated with varying lengths and widths.
The results obtained from these three techniques will be compared and discussed, and it is expected that this work will
enable the characterization of residual stress in micro-structures after they have been released.
Applications I
Concentration effect of the Au-pattern on a cellulose paper using μ-contact printing technique
Show abstract
The electro-active paper (EAPap) has been investigated as a light-weight and low power consuming actuator. The
EAPap cannot be utilized conventional lithography technique for fabrication of metal pattern due to its hydrophilic and
flexible properties. A metal pattern fabrication on the EAPap is a beginning step for the integration of the paper actuators
and micro-electronics. To overcome the drawback of the EAPap, a micro-contact printing (μ-CP) technique was utilized
to fabricate Au-patterns on EAPap. Large number of cracks or nanograins was observed on the transferred Au-pattern.
These defects were closely related with the solvent polarity during the fabrication of adhesion self-assembly monolayer
(SAM). To investigate the cause of defects, three different solvents having different polarity were utilized during the
SAM layer fabrication process. The ethanol having high polarity was utilized to investigate the effect of the 3-
mercaptopropyltrimethoxysilane (MPTMS) concentration on micro or nano-defect formation.
Active coatings technologies for tailorable military coating systems
Show abstract
The main objective of the U.S. Army's Active Coatings Technologies Program is to develop technologies that
can be used in combination to tailor coatings for utilization on Army Materiel. The Active Coatings Technologies
Program, ACT, is divided into several thrusts, including the Smart Coatings Materiel Program, Munitions Coatings
Technologies, Active Sensor packages, Systems Health Monitoring, Novel Technology Development, as well as other
advanced technologies. The goal of the ACT Program is to conduct research leading to the development of multiple
coatings systems for use on various military platforms, incorporating unique properties such as self repair, selective
removal, corrosion resistance, sensing, ability to modify coatings' physical properties, colorizing, and alerting logistics
staff when tanks or weaponry require more extensive repair. A partnership between the U.S. Army Corrosion Office at
Picatinny Arsenal, NJ along with researchers at the New Jersey Institute of Technology, NJ, Clemson University, SC,
University of New Hampshire, NH, and University of Massachusetts (Lowell), MA, are developing the next generation
of Smart Coatings Materiel via novel technologies such as nanotechnology, Micro-electromechanical Systems (MEMS),
meta-materials, flexible electronics, electrochromics, electroluminescence, etc.
This paper will provide the reader with an overview of the Active Coatings Technologies Program, including an
update of the on-going Smart Coatings Materiel Program, its progress thus far, description of the prototype Smart
Coatings Systems and research tasks as well as future nanotechnology concepts, and applications for the Department of
Defense.
Fabrication of nonlinear plastic optical fiber (POF) and application
Show abstract
We have developed a fabrication technique for plastic optical fiber (POF) using nonlinear organic materials. The
fabrication technique is the direct core solution injection into the hole of cladding preform formed by
polymerization of cladding solution. The cladding solution was made of MMA, BBP, and BPO. The preform of
fiber was drawn into fiber following polymerization of core solution in cladding preform. We used DR1 to
control the refractive index of fiber and investigated the sensor characteristics. The sensitivity of fabricated fiber
is about 0.11 W/°C in the temperature range from 20 °C to 100 °C.
Lifetime characterization of powercapacitive RF MEMS switches
Show abstract
RF MEMS switches provide a low-cost, high performance solution for many RF/microwave applications these
switches will be important building blocks for designing phase shifters, switched filters reflector array antennas
for military and commercial markets.
In this paper, progress in characterizing of THALES capacitive MEMS devices under high RF power is
presented. The design, fabrication and testing of capacitive RF MEMS switches for microwave/mm- wave
applications on high-resistivity silicon substrate is presented. The switches tested demonstrated power handling
capabilities of 1W (30 dBm) for continuous RF power. The reliability of these switches was tested at various
power levels indicating that under continuous RF power. In addition a description of the power failures and their
associated operating conditions is presented.
The PC-based test stations to cycle switches and measure lifetime under DC and RF loads have been developed.
Best-case lifetimes of 1010 cycles have been achieved in several switches from different lots under 30 dbm RF
power.
Energy harvesting of dipole rectenna for airship applications
Show abstract
There are several potential candidate energy harvesting technologies for smart actuators and
devices, such as space vehicles, high altitude airships, MAVs (Micro-Aero Vehicles), and
smart robots. Smart material actuators have actively been developed during the last couples of
decades for controlling flow-fields over aircraft wings, shape changes for step-motions, or discrete motion of actuators, but their applications as a practical system are limited due to hardwire circuits and high voltage requirements. The wired power configuration provides lack of maneuverability of the system, especially it is not possible for micro aerial vehicles (MAVs), space vehicles, and airship applications. In addition, the hard wiring may not be a suitable
solution due to the network complexity. Moreover, the weight increase may be attributed to the a wired network, the complex gate switching of power and control networks needed, and the
interdependency of power and control routines needed.
Flexible dipole rectenna devices appeared to be attractive for various applications because of
the adaptability on complex structures; possibility for higher power density features, and ability
of high coupling efficiency. In this paper, design concepts and results for various flexible dipole
rectennas as well as effects of incident angle of microwave energy on rectennas will be discussed including their efficiencies. The discussion will also include the effects of distance
between microwave source and rectennas on airship vehicles. Using the result, some applications of the system will also be addressed.
Nanostructures
Experimental investigation of magnetic nanotubes in PC-12 neuron cells culturing
Show abstract
This report discusses the effects of magnetic nanotubes on the differentiation and growth of neurons. The magnetic
nanotubes used in this study are hematite nanotubes synthesized using template method, and their structural and
magnetic properties have been characterized by scanning electron microscopy (SEM), transmission electron microscopy
(TEM) and vibrating sample magnetometer (VSM). PC-12 cells are differentiated into neurons in the presence of
magnetic nanotubes to confirm the biocompatibility and cytotoxic effects of magnetic nanotubes during the processes of
neuron differentiation and neuronal growth. The morphological changes and synapse formation of neurons are
investigated, and the contact effects of magnetic nanotubes on neurite (axon and dendrites) outgrowth are explored. This
research allows us to understand the interaction between magnetic nanomaterials and neurons, and pave the way towards
developing potential treatments using the magnetic nano tubes for neurodegenerative disorders and injuries to the
nervous system in the future.
Nano-bio quantum technology for device-specific materials
Show abstract
Progress in nanoscale science enabled a radically new perspective on the fundamental properties
of materials affecting a wide range of applications. For example, nanoscale photonic materials
offer size-dependent emission spectra and a high stability over a wide range of temperatures.
Biologically inspired materials used as a building block or a template enable nano-fabrication of
materials for quantum applications, such as quantum-dot lasers, quantum logic gates, and
quantum computing. A combination of bio and nano features breeds new kinds of materials with
potential for energy harvesting and storage. Artificially driven quantum constraints on intrinsic
level transitions within thin-film or quantum-dot structures offer new possibilities for optical
device technology. However, such application-specific nanoscale fabrication of materials
requires advanced measurement and manipulation technologies to characterize the uniqueness of
nanoscale materials in electromagnetic, thermal, photonic, and structural properties and functions
in nanoscale materials.
Several new application-specific nano-bio technologies, such as bionanobattery, bio-template for
size-controlled quantum-dots, quantum aperture, and smart optical devices which were
developed by a group of researchers at NASA Langley Research Center (LaRC) will be
discussed. These applications illustrate the fusion of bio, nano, and quantum technologies.
Biosensors and BioMEMS I
High-speed microfluidic thermal stimulator for temperature-activated ion channel studies
Show abstract
In this paper we have designed and built a microfluidic thermal chip that provides rapid temperature changes in
the solution combined with accurate temperature control. The thermal chip was designed to facilitate the patch-clamp to
study temperature dependent activities of ion channels. The device consists of a fluid channel for perfusing solution
connected to an accessible reservoir for making patch-clamp measurements on individual cells. A thin film platinum
heater was used to generate rapid temperature change and the temperature was monitored using a thin film resistor. The
thermal chip was constructed using SU-8 materials on glass wafer to minimize the heat loss to the substrate and channel
walls. The chip was characterized for various flow rates ranging from 0.0093 mL/min to 0.0507 mL/min with heater
power ranging from 2.7 to 19.4 mW. The heating element is capable of alternating the temperature ranging from bath
temperature (20°C) to 90°C at maximum heating rate of 1°C/10 ms. Using the chip, patch clamp recordings were made
on cultured HEK cells as the temperature was rapidly varied. The results demonstrated that the thermal chip could be
used as a thermal clamp for many thermosensitive ion channel studies.
Nanowire integrated microelectrode arrays for lab-on-a-chip applications
Show abstract
The monitoring of biological signals generated during nerve excitation and cell-to-cell communication are important for
design and development of novel materials and methods for laboratory analysis. In-vitro biological applications such as
drug screening and cell separation also require cell-based biosensors. The sensing technology is based on the optical or
electrical read-out from the lab-on-a-chip. The electrophysiological activity of certain cells such as neurons and cardiac
cells are monitored using planar microelectrode arrays integrated with microfluidic devices. One of the main issues of
the current microelectrode array design is the difficulty in selective integration and the size dependency of its
impedances along with a large amount of noise in the circuit due to this mismatch. It is quite evident that
nanotechnology can solve these problems and an efficient electrical interconnection is possible using nanodevices. This
paper presents the design and development of planar microelectrode arrays integrated with vertically aligned nanowires
for lab-on-a-chip device applications. The higher surface area densities of such nanowire integrated microelectrode
arrays show promising results in impedance control for the integration of lab-on-a-chip devices. We have fabricated
microelectrode arrays on silicon and flexible polymer substrates and vertically aligned nanowires were fabricated onto it
using template method. High degree of specific growth is obtained by controlling the nanowire growth parameters.
A miniature fiber optic pressure sensor for intervertebral disc pressure measurements of rodents
Show abstract
Lower back pain continues to be a leading cause of disability in people of all ages, and has been associated with
degenerative disc disease. It is well accepted that mechanical stress, among other factors, can play a role in the
development of disc degeneration. Pressures generated in the intervertebral disc have been measured both in vivo and in
vitro for humans and animals. However, thus far it has been difficult to measure pressure experimentally in rodent discs
due to their small size. With the prevalent use of rodent tail disc models in mechanobiology, it is important to
characterize the intradiscal pressures generated with externally applied stresses.
In this paper, a miniature fiber optic Fabry-Perot interferometric pressure sensor with an outer diameter of 360 &mgr;m was
developed to measure intradiscal pressures in rat caudal discs. A low coherence interferometer based optical system was
used, which includes a broadband light source, a high-speed spectrometer, and a Fabry-Perot sensor. The sensor employs
a capillary tube, a flexible, polymer diaphragm coated with titanium as a partial mirror, and a fiber tip as another mirror.
The pressure induced deformation of the diaphragm results in a cavity length change of the Fabry-Perot interferometer
which can be calculated from the wavelength shift of interference fringes. The sensor exhibited good linearity with small
applied pressures. Our validation experiments show that owing to the small size, inserting the sensor does not disrupt
the annulus fibrosus and will not alter intradiscal pressures generated. Measurements also demonstrate the feasibility of
using this sensor to quantify external load intradiscal pressure relationships in small animal discs.
Biosensors and BioMEMS II
Immersive training and mentoring for laparoscopic surgery
Show abstract
We describe in this paper a training system for minimally invasive surgery (MIS) that creates an immersive training
simulation by recording the pathways of the instruments from an expert surgeon while performing an actual training task.
Instrument spatial pathway data is stored and later accessed at the training station in order to visualize the ergonomic
experience of the expert surgeon and trainees.
Our system is based on tracking the spatial position and orientation of the instruments on the console for both the
expert surgeon and the trainee. The technology is the result of recent developments in miniaturized position sensors that
can be integrated seamlessly into the MIS instruments without compromising functionality. In order to continuously
monitor the positions of laparoscopic tool tips, DC magnetic tracking sensors are used. A hardware-software interface
transforms the coordinate data points into instrument pathways, while an intuitive graphic user interface displays the
instruments spatial position and orientation for the mentor/trainee, and endoscopic video information. These data are
recorded and saved in a database for subsequent immersive training and training performance analysis. We use two 6
DOF DC magnetic trackers with a sensor diameter of just 1.3 mm - small enough for insertion into 4 French catheters,
embedded in the shaft of a endoscopic grasper and a needle driver. One sensor is located at the distal end of the shaft
while the second sensor is located at the proximal end of the shaft. The placement of these sensors does not impede the
functionally of the instrument. Since the sensors are located inside the shaft there are no sealing issues between the
valve of the trocar and the instrument.
We devised a peg transfer training task in accordance to validated training procedures, and tested our system on its
ability to differentiate between the expert surgeon and the novices, based on a set of performance metrics. These
performance metrics: motion smoothness, total path length, and time to completion, are derived from the kinematics of
the instrument. An affine combination of the above mentioned metrics is provided to give a general score for the
training performance.
Clear differentiation between the expert surgeons and the novice trainees is visible in the test results. Strictly
kinematics based performance metrics can be used to evaluate the training progress of MIS trainees in the context of
UCLA - LTS.
A total patient monitoring system for point-of-care applications
Show abstract
Traditionally, home care for chronically ill patients and the elderly requires periodic visits to the patient's
home by doctors or healthcare personnel. During these visits, the visiting person usually records the
patient's vital signs and takes decisions as to any change in treatment and address any issues that the patient
may have. Patient monitoring systems have since changed this scenario by significantly reducing the
number of home visits while not compromising on continuous monitoring. This paper describes the design
and development of a patient monitoring systems capable of concurrent remote monitoring of 8 patient-worn
sensors: Electroencephalogram (EEG), Electrocardiogram (ECG), temperature, airflow pressure,
movement and chest expansion. These sensors provide vital signs useful for monitoring the health of
chronically ill patients and alerts can be raised if certain specified signal levels fall above or below a preset
threshold value. The data from all eight sensors are digitally transmitted to a PC or to a standalone network
appliance which relays the data through an available internet connection to the remote monitoring client.
Thus it provides a real-time rendering of the patient's health at a remote location.
Electro-fluid-structural interaction simulation of a valveless micropump
Show abstract
In this paper, the pumping performance of a piezoelectric micropump is simulated with the commercial finite element
analysis software COMSOL Multiphysics 3.2a. The micropump, which was developed in our previous work, is
composed of a four-layer lightweight piezocomposite actuator, a polydimethylsiloxane (PDMS) pump chamber, and two
diffusers. The piezoelectric domain, the structural domain and the fluid domain are coupled in the simulation. The water
flow rates are numerically predicted for geometric parameters of the micropump. This study confirms that the micropump is optimally designed to obtain its maximum pumping performance.
On-line carbon nanotube-based biosensors in microfluidic channels
Show abstract
Highly aligned double wall carbon nanotubes (DWCNT) and multi-wall carbon nanotubes (MWCNT) were
synthesized in the shape of towers and embedded into microchannels for use as a biosensor. The towers were
fabricated on a substrate patterned in 1mm x 1mm blocks with 1 mm spacing between the blocks. Chemical vapor
deposition was used for the nanotube synthesis process. Patterned towers up to 8 mm high were grown and easily
peeled off the silicon substrate. A nanotube electrode was then soldered on printed circuit boards and epoxy was cast
into the tower under pressure. After curing, the top of the tower was polished. RF-plasma at 13.56 MHz was used to
enhance the electrocatalytic effect of the nanotube electrode by removing excess epoxy and exposing the ends of the
nanotubes. Au particles were electrodeposited on the plasma treated tower electrode. Cyclic voltammetry (CV) for
the reduction of 6 mM K3Fe(CN)6 (in a 1.0 M KNO3 supporting electrolyte) was performed to examine the redox
behavior of the nanotube tower electrode. Next, a master mold for polydimethylsiloxane (PDMS) was patterned
using SU-8 and then a Pt disk electrode was embedded into the PDMS. The final fluidic channel between the epoxy-nanotube
electrode and PDMS was sealed using a UV-curing adhesive. Impedance between the Pt and nanotube
electrodes was monitored while flowing different solutions and LNCaP prostate cells. The impedance changed in
proportion to the concentration of cells in the solution. A needle-type composite microelectrode was then fabricated
by injecting a carbon nanotube-epoxy solution into a pulled-glass tube. CV and differential pulse voltammetry
(DPV) to detect dopamine were showed a highly linear response with a sensitivity 100 nA/mM. Based on the
impedance results using the flowing cells and the CV and DPV results, carbon nanotube microelectrodes are a
promising candidate for cancer cell detection and neurotransmitter detection.
Biosensors and BioMEMS III
Integrated polymer multimode waveguides for microfluidic sensing applications
Show abstract
The proposed technology platform allows the fabrication of disposable volume-optical measurement devices in combination with microfluidic channels and reservoirs at an affordable price. The sensor can be easily integrated into more complex polymer based Lab-on-Chips to increase their functionality towards integrated volume-optical sensing. Its possible applications can be found not only in biomedical sensing, but also in monitoring of chemical reaction in micro chambers as well as in the fields of food and environmental control.
Piezoelectric 3D nanostructures for developing point-of-care biosensors
Show abstract
Minimal invasive determinations of various physiological parameters are more and more demanding for medical
applications. Many techniques have been evolved in nanotechnology using one dimensional nanostructures to aid the
analytical tools for chemical and biosensing, disease diagnosis and treatment. Nanowire sensing probes have potential
applications not only in electronics and optoelectroncs industry, but have tremendous potential in evaluating minute
changes in cellular level, particularly for designing various sensing and diagnosis tools. A review of the development of
vertically aligned piezoelecronic nanowire arrays and 3-D nanostructures for the design of biomedical sensors for pointof-
care applications are presented in this paper. The deflections of a vertically aligned piezoelectric nanowire arrays can
be used for the generation of voltages and can be used for the measurement of various parameters such as pressure,
temperature, blood flow and glucose detection. Vertically aligned ZnO nanostructure has the advantages of generating
piezoelectric voltages that can be coupled with MEMS sensors for the development of point-of-care biosensors.
MEMS glaucoma monitoring device
Show abstract
Glaucoma is a serious disease, affecting millions of people worldwide requiring continuous monitoring of Intra
Ocular Pressure (IOP) to avoid the risk of blindness. Current laboratory measurements are infrequent, intrusive
and do not indicate the progression of the disease. The paper reports on the development of an implantable
Glaucoma monitoring system that can monitor IOP in the eye to indicate any elevation in risk to the patient. A
mathematical model of the anterior chamber of the eye was used
to analyze the complex fluid flow and pressure balance in the eye. This was done in order to determine the
performance requirements of the actuator, sensor and transmission electronics that could be integrated on a single
microchip using microelectromechanical systems (MEMS) technology, to carry out the testing internally. The
accuracy of the system was theoretically tested against results from external medical tests. The results were found
to be comparable.
Viability study of oscillatory flow pumps using bimorph piezoelectric actuators
Show abstract
Precision flow pumps have been widely studied over the last three decades. They have been applied in the areas of
Biology, Pharmacy and Medicine in applications usually related to the dosage of medicine and chemical reagents.
In addition, thermal management solutions for electronic devices have also been recently developed using these
kinds of pumps offering better performance with low noise and low power consumption. In a previous work, the
working principle of a pump based on the use of a bimorph piezoelectric actuator inserted in a fluid channel to
generate flow was presented. In this work, a novel configuration of this piezoelectric flow pump that consists
of a flow pump using two bimorph piezoelectric actuators in parallel configuration has been studied and it is
presented. This configuration was inspired on fish swimming modes. The complete cycle of pump development
was conducted, consisting in designing, manufacturing, and experimental characterization steps. Load-loss and
flow rate characterization experimental tests were conducted, generating data that allows us to analyze the
influence of geometric parameters in the pump performance. Comparisons among numerical and experimental
results were made to validate the computational results and improve the accuracy of the implemented models.
Applications II
Measurement of stresses in MEMS structures by stress release
Show abstract
The paper presents a recently developed method of measuring frozen elastic stresses in micro components and devices.
The approach bases on stress release at the component surface by focused ion beam (FIB) milling. Stresses are deduced
from the experimentally determined deformation field around the FIB milling pattern, applying reasonable stress
hypotheses and appropriate modeling of the stress release field. Because of the local nature of ion milling and the
limited material volume affected by deformation, the method suites to very local stress measurement. Commonly,
spatial resolution is achieved in a range from submicron to some tens of microns. Residual stresses in membrane type
MEMS structures have been measured and results are reported. A broader group of potential applications is expected for
non-membrane structures in micro-/nanosystems or their packaging. Possible approaches for those cases are discussed,
considering comparison of measured deformation fields with either analytical solutions of the mechanical problem or
with finite element simulations.
Three-dimensional fiber optical trap for cell manipulation and force measurement
Show abstract
Three dimensional cell manipulation using two inclined fibers with lensed tips is demonstrated. For the first time, the
relationship between optical forces and cell positions is experimentally characterized in such an optical fiber trap, which
exhibits a good linearity in the vicinity of the equilibrium. The system is capable of being a force sensor with a
resolution of around 1 pN/&mgr;m. The spring constant is found to be dependent on the cell's shape: a prolate cell entails a
larger spring constant than that of a round cell with a similar size. Numerical analysis is carried out by using a modified
ray optics model with a spheroidal object in the trap. The spring constant obtained from the analysis also depends on the
shape of a cell, which agrees with the experimental results. The fiber optical tweezers have great potential for threedimensional
manipulation and force measurement of cells.
D-Fiber volatile organic compound sensor
Show abstract
A fiber-optic volatile organic compound sensor is described. The sensor consists of a single-mode D-fiber with a
polydimethylsiloxane layer. The polydimethylsiloxane layer is applied to the fiber flat after removal of a section of the
fiber's supercladding in order to increase evanescent interaction of the light with the layer. Absorbance of volatile
organic compounds alters the refractive index of the layer, resulting in a birefringent change. This change is observed as
a shift in polarization of the light carried by the fiber. Sensor response is observed for dichloromethane and acetone in
gas and liquid concentrations respectively.
Hologram-based humidity indicator for domestic and packaging applications
Show abstract
A passive indicator for Relative Humidity based on a photopolymer recorded hologram has been developed. The
indicator works on the principle that the wavelength reconstructed by a reflection hologram is dependent on the spacing
between the fringe planes of the hologram. As the Relative Humidity changes, the hologram swells or shrinks and the
apparent colour of the reconstructed image changes.
The response time, operational range and reversibility of the indicator have been studied in a controlled humidity
environment. Response times from less than a minute to tens of minutes depending on the holograms physical properties
have been measured. Indicators with different operational ranges have been designed. For some indicators the
operational range extends from 10% RH to 80% RH.
The indicator is completely reversible in its present formulation. It could have an extensive market in industrial
monitoring, food packaging and household applications.
Uncertainty analysis of mircoresonator using classical and interval methods
Show abstract
This paper presents an uncertainty analysis of micro electro mechanical systems using analytical methods and interval
analysis. Laterally driven polysilicon resonant micro structure is considered to illustrate the analysis.
Packaging
The role of nanotechnology and nano and micro-electronics in monitoring and control of cardiovascular diseases and neurological disorders
Show abstract
Nanotechnology has been broadly defined as the one for not only the creation of functional
materials and devices as well as systems through control of matter at the scale of 1-100 nm, but
also the exploitation of novel properties and phenomena at the same scale. Growing needs in the
point-of-care (POC) that is an increasing market for improving patient's quality of life, are driving
the development of nanotechnologies for diagnosis and treatment of various life threatening
diseases. This paper addresses the recent development of nanodiagnostic sensors and
nanotherapeutic devices with functionalized carbon nanotube and/or nanowire on a flexible organic
thin film electronics to monitor and control of the three leading diseases namely 1)
neurodegenerative diseases, 2) cardiovascular diseases, and 3) diabetes and metabolic diseases.
The sensors developed include implantable and biocompatible devices, light weight wearable
devices in wrist-watches, hats, shoes and clothes. The nanotherapeutics devices include
nanobased drug delivery system. Many of these sensors are integrated with the wireless systems
for the remote physiological monitoring. The author's research team has also developed a wireless
neural probe using nanowires and nanotubes for monitoring and control of Parkinson's disease.
Light weight and compact EEG, EOG and EMG monitoring system in a hat developed is capable of
monitoring real time epileptic patients and patients with neurological and movement disorders
using the Internet and cellular network. Physicians could be able to monitor these signals in realtime
using portable computers or cell phones and will give early warning signal if these signals
cross a pre-determined threshold level.
In addition the potential impact of nanotechnology for applications in medicine is that, the devices
can be designed to interact with cells and tissues at the molecular level, which allows high degree
of functionality. Devices engineered at nanometer scale imply a controlled manipulation of
individual molecules and atoms that can interact with the human body at sub-cellular level. The
recent progress in microelectronics and nanosensors crates very powerful tools for the early
detection and diagnosis. The nanowire integrated potassium and dopamine sensors are ideal for
the monitoring and control of many cardiovascular diseases and neurological disorders. Selected
movies illustrating the applications of nanodevices to patients will be shown at the talk.
Integrated Nano- and Micro-structures
Development of poly-3-hexylthiophene based ISFET sensors for biomedical applications
Show abstract
Ion-sensitive Field-Effect Transistors (ISFETs) have been applied for in vitro and online detection for clinical purposes
such as concentration of urea, penicillin-G and potassium ion (K+). They have proven to be highly sensitive, shown less
response time, reproducible and smaller than the piecewise assembled conventional biosensors. Materials like p3HT,
Tantalum Oxide and PVA-SbQ have show their merit as components of various FETs fabricated on silicon substrate.
This paper discusses the feasibility of using them together along with design enhancements such as zigzag inter-digitated
electrode. The results hitherto obtained have been analyzed and conclusions are drawn to set future course of
experimentation to develop the ISFET for sensor applications.
Memory-based robust adaptive control of a variable length stepping nanomanipulator
Show abstract
This paper presents the modeling and memory-based robust adaptive control of a variable length stepping
nanomanipulator. A three degree of freedom (3DOF) nanomanipulator with revolute revolute prismatic (RRP) actuator
structure, namely here MM3A, is utilized for a variety of nanomanipulation tasks. Unlike widely used Cartesian-structure
nanomanipulators, the MM3A is equipped with revolute-piezoelectric actuators which result in outstanding
performance for controlling the nanomanipulator's tip alignment during the nanomanipulation process. However, the
RRP structure of the nanomanipulator introduces complicity in kinematic and dynamic equations of the system which
needs to be addressed in order to control the nanomanipulation process. Dissimilar to the ordinary piezoelectric actuators
which provide only a couple of micrometers working range, the piezoelectric actuators utilized in MM3A, namely
Nanomotors, provide wide range of action (120° in revolute actuators and 12mm in prismatic actuator) with sub-nano
scale precision (0.1 μrad in revolute actuators and 0.25 nm in prismatic actuator). This wide range of action combined
with sub-nano scale precision is achieved using a special stick/slip moving principle of the Nanomotors. However,
such stick/slip motion results in stepping movement of the MM3A. Hence, due to the RRP structure and stepping
movement principle of the MM3A nanomanipulator, controller design for the nanomanipulation process is not a trivial
task. In this paper, a novel memory-based robust adaptive controller is proposed to overcome these shortfalls. Following
the development of the memory-based robust adaptive controller, numerical simulations of the proposed controller are
preformed to demonstrate the positioning performance capability of the controller in nanomanipulation tasks.
Studying insect motion with piezoelectric sensors
Show abstract
Piezoelectric materials have been widely used in applications such as transducers, acoustic components, as well as
motion, pressure and airborne sensors. Because of the material's biocompatibility and flexibility, we have been able to
apply small piezoelectric sensors, made of PVDF, to cockroaches. We built a laboratory test system to study the
piezoelectric properties of a bending sensor. The tested motion was compared with that of the sensor attached to a
cockroach. Surface characterization and finite element analysis revealed the effects of microstructure on piezoelectric
response. The sensor attachment enables us to monitor the insects' locomotion and study their behaviors. The
applications of engineering materials to insects opens the door to innovating approaches to integrating biological,
mechanical and electrical systems.
Development of amperometric glucose sensors with heterostructured nanowire arrays for continuous subcutaneous monitoring
Show abstract
This research discusses the development of a novel amperometric sensor to detect glucose concentrations in solution
without the need for an artificial mediator. Since the intended goal of this research is to develop a glucose sensor to
subcutaneously monitor glucose levels in the body, it is important that the sensor does not require a mediator, since such
chemicals would prove harmful to the body. Nanowire arrays were used as the sensing electrode in place of planar
electrodes to utilize the unique properties of nanostructures. Heterostructured Au/Pt nanowires were used so that the
dual roles of covalent immobilization of glucose oxidase and oxidation of hydrogen peroxide could be carried out by the
sensing electrode. Glucose oxidase was immobilized on these nanowires using self- assembled monolayers of
alkanethiols and using a conducting polypyrrole matrix. Results indicate that the unique structure of the sensing
electrode delivers superior performance with regards to sensitivity and response time in the absence of an artificial
mediator. The development of such a sensor would assist the treatment of patients in an effective and timely manner.
Ongoing efforts will help understand the process fabrication and analysis in detail.
Fabrication and Characterization
Coupled flexural-torsional nonlinear vibrations of microcantilever beams
Show abstract
In this paper the problem of coupled flexural-torsional nonlinear vibrations of a piezoelectrically-actuated
microcantilever beam is investigated considering beam's simultaneous flexural, torsional and longitudinal vibrations.
Application of such problem is utilized in several nanotechnological instruments such as atomic force microscopy,
nanomechanical cantilever sensors and friction force microscopy. The actuation and sensing are both facilitated through
bonding a piezoelectric layer (here, ZnO) on the microcantilever surface. The piezoelectric properties combined with
nonlinear geometry of the beam introduce both linear and nonlinear coupling between flexural vibration as well as
longitudinal and torsional vibrations. The governing equations of motion are obtained with piezoelectric nonlinearity
appearing in quadratic form while inertia and stiffness nonlinearities as cubic. An experimental setup consisting of a
commercial piezoelectric microcantilever installed on the stand of an ultramodern laser-based microsystem analyzer is
designed and utilized to verify the theoretical developments. First and second flexural natural frequencies are both
experimentally and numerically obtained and are shown to be in good agreement. Both linear and nonlinear simulation
results are compared with experimental results and it is observed that nonlinear modeling response matches the
experimental findings very closely.
Visualization of buried structures in atomic force acoustic microscopy
Show abstract
Advanced Scanning Probe Microscopy (SPM) modes such as Atomic Force Acoustic Microscopy (AFAM) and
Ultrasonic Force Microscopy (UFM) combine Atomic Force Microscopy (AFM) with an excitation of the sample or
cantilever by ultrasound. These techniques become increasingly powerful tools for the determination of material
properties on nanoscale.
Non-destructive evaluation of subsurface and buried structures is getting more and more important in semiconductor
industries and electronics system integration technology. Existing methods that allow subsurface measurements with
high local resolution are mostly based on destructive concepts as surface ablation by Focused Ion Beam (FIB) devices.
It is widely discussed in literature that AFAM and UFM techniques should have the capability to detect subsurface
features. But direct proofs of this capability are hard to find. The difficulty comes from the point that in UFM and
AFAM images besides elastic contrast also topological contrast is mixed in. So, for a direct proof samples are needed
which (a) show subsurface contrast and (b) having definitely no surface topology correlated with the subsurface feature
in question. These samples are not so easy to obtain. An appropriate sample fabrication technology was developed based
on the focussed ion beam technique. Using the machined samples the buried structure visibility for the AFAM technique
could be proved uniquely. The results are compared with conclusions from modelling.
Study of the transverse shear mode resonator with coupled viscoelastic layer by scanning tunneling microscopy
Chueh-Yu Wu,
Chun-Kuang Chen,
Kuang-Chong Wu,
et al.
Show abstract
Nowadays, the classical modeling of quartz crystal microbalance (QCM) describes the relationship between
frequency and mass; resistance and viscosity are widely accepted and used for many years. It is clear that the mass
loading decreases the resonance frequency, and the viscoelastic damping increases the resistance of quartz resoance.
Due to rapidly advancement of electronics techniques, these effects can be easily read out through an advanced
electronic circuitry precisely. However, the influence of the oscillatory condition by a bio-molecule layer on the top of
quartz is more complex and beyond the scope of classical model due to coupled vicoelastic effect. The dynamics of the
quartz crystal shear mode resonance are difficult observed by traditional metrology techniques because of the very small
vibration amplitude. Scanning tunneling microscope (STM) which can scan the surface in atomic level provides a new
route to study and analyze the interaction between quartz and bio-molecule viscoelastic layers. STM not only can detect
the tiny vibrational changes but also can observes the process of growth of a viscoelastic layer consisting of biological
materials. The measurement of dynamic behaviors of QCM with STM will be presented in this paper.
Poster Session
Microwave power transmission of flexible dipole rectenna for smart sensors and devices
Show abstract
There are several potential candidates for energy transmission technologies suitable for smart actuators and
sensors. Smart materials have actively been developed in previous decades in order to sense environmental changes
or to actuate proper devices, but their applications as a practical system are limited due to the requirements of hardwire
circuits and power supply. These limiting factors have been key challenges to overcome for practical
applications of smart materials. This paper presents the design, fabrication and test of flexible dipole rectenna arrays
for wireless microwave power transmission. Low voltage/high current rectenna array is designed and the maximum
current of 980 mA and the maximum power of 7.2 W are observed. Since this rectenna array is sensitive to the
polarization angle, a polarization-free rectenna array is designed. Output voltage, current, power, efficiency and the
influence of polarization angle as well as incidence angle on the performance of rectenna array are investigate.
Immobilization of ε-polylysine onto the probe surface for molecular adsorption type endotoxin detection system
Show abstract
Patients with renal failure become not able to expel the waste product, and they accumulate the toxic products for
themselves. They therefore must use the hemodialysis to weed out the metabolic decomposition product. Hemodialysis
for chronic renal failure is the most popular treatment method with artificial organs. However, hemodialysis patients
must continue the treatment throughout their life, the results of long term extracorporeal dialysis, those patients develop
the various complications and diseases, for example, dialysis amyloidosis etc. Dialysis amyloidosis is one of the
refractory complications, and the prevention of this complication is important. Recently, endotoxin is thought to be the
most likely cause of the complication.
Endotoxin is one of the major cell wall components of gram-negative bacteria, and it forms the complex with proteins
and lipopolysaccharide (LPS). It has various biological activities, e.g. attack of fever, when it gets mixed into human
blood. In addition, it is known that large amount of endotoxin exists in living environment, and medicine is often
contaminated with endotoxin. When contaminated dialyzing fluids are used to hemodialysis, above-mentioned dialysis
amyloidosis is developed. Therefore, it is important that the detection and removal of endotoxin from dialyzing fluids.
Until now, the measurement methods using Limulus Amebosyte Lysate (LAL) reagent were carried out as the tests for
the presence of endotoxin. However, these methods include several different varieties of measurement techniques. The
following are examples of them, gelatinization method, turbidimetric assay method, colorimetric assay method and
fluoroscopic method. However, these techniques needed 30-60 minutes for the measurement. From these facts, they are
not able to use as a "real-time endotoxin detector". The detection of endotoxin has needed to carry out immediately, for
that reason, a new "real-time" detection method is desired.
We focused attention to adsorption reaction between &egr;-polylysine and endotoxin. &egr;-polylysine has the structure of
straight chain molecule composed by 25-30 residues made by lysine, and it is used as an antimicrobial agent, moreover,
cellulose beads with immobilized &egr;-polylysine is used as the barrier filter for endotoxin removal. Therefore, it is
expected that the endotoxin be adsorbed to the immobilized &egr;-polylysine onto the probe. As the result of this reaction,
the mass of the probe is increased, and endotoxin can be detected by using of Quartz Crystal Microbalance (QCM). In
our previous research, we have already acquired the proteins immobilization technique onto Au and Si surface. In this
report, the proposal of molecular adsorption type endotoxin detection system, and the immobilization of &egr;-polylysine
onto the probe are described. We use X-ray Photoelectron Spectroscopy (XPS) to confirm the &egr;-polylysine
immobilization, and the adsorptive activity of immobilized &egr;-polylysine is measured by XPS and AFM. The purpose of
this study is to bring about the realization of "Real-time endotoxin detection system".
Dynamic simulation of microresonator-based differential pressure sensor
Show abstract
In this paper, a Micro resonating sensor with split mass concept is designed and analyzed for differential quantity
measurement by extending the two mass concepts with one more drive mass. The model of the proposed resonator is
derived and represented in state space form. The performance for differential pressure sensing is analyzed using
MATLAB. The simulation results demonstrates that the first split mode frequency of third mass exhibiting high
resonating magnitude variation with the differential pressure, which is simulated by varying the stiffness of the drive
masses.
Variable structure control of shape memory alloy actuated flexible smart structure
Show abstract
This paper presents the design of reaching law based discrete time sliding mode control for the SMA actuated cantilever
beam to suppress the vibration in the presence of external disturbance. A linear dynamic model of the SMA actuated
cantilever beam structure is experimentally established using online ARX RLS system identification approach. A digital
control system that consists of simulink modeling software and dSPACE 1104 controller board has been used for
identification. The VSC controller is designed starting with the switching surface design. The eigen values of the reduced
order system are located suitably so that it lies inside the unit circle and the system is stable. The performance of the
controller for vibration suppression and disturbance rejection was evaluated through simulation by exciting the structure
at resonance.
Cylindrical nanocavity and nanowire electrodes for redox cycle dopamine sensing: design, fabrication, and characterization
Show abstract
We investigated the use of a three dimensional, cylindrical nanocavity structure with two working electrodes for use in
dopamine sensing using redox cycling. This method of dopamine detection has been an active area of research for many
years, with sensor designs developing to smaller and smaller sizes, as detection limits approach those needed for an in
vivo dopamine detector. Toward that end, the nanocavity structure, based around a field of vertically oriented nanowires,
was conceived, fabricated, and tested for feasibility. Each nanowire serves as one of the working electrodes, while the
second is formed as a semi-enclosing cylindrical shell, with an inter-electrode spacing of .2um.
Glucose sensing based on Pt-MWCNT and MWCNT
Show abstract
It is known that multi walled carbon nanotubes (MWCNTs) is an excellent materials for biosensing applications and
with the introduction of Pt nanoparticles (Pt-MWCNTs) of about 3nm in diameter in MWCNTs greatly increases the
current sensitivity and also the signal to noise ratio. We fabricated the CNT- based glucose sensor by immobilization the
bio enzyme, glucose oxidase (GoX), on the Pt-MWCNT and electrode were prepared. The sensor has been tested
effectively for both the abnormal blood glucose levels- greater than 6.9 mM and less than 3.5 mM which are the
prediabetic and diabetic glucose levels, respectively. The current signal obtained from the Pt-MWCNT was much higher
compared to the MWCNT based sensors.
Synthesis and photonic property study of ZnO nanowires for a real time photodynamic therapy monitoring probe
Show abstract
In this paper, we present how the photonic properties of zinc oxide (ZnO) nanowires can be used to potentially
advance the effectiveness of Photodynamic therapy (PDT), one of the most recent and promising approaches among
cancer therapies. Presently, PDT employs laser light to activate intravenously or topically administered photosensitizers
to give rise to highly reactive singlet oxygen which has a very short lifetime and is capable of biochemical damage to
cell membranes of the tumor. A probe that can monitor in real time the penetration depth of the laser in the tumor and
also the evolution of the singlet oxygen, which is critical for tumor eradication, is capable of improving the efficacy of
PDT quite significantly. Such a probe, by providing real time feedback, can help us determine whether to increase or
decrease the light exposure dose and also if further local administration of photosensitizers is required or not. ZnO
nanowires are known to be photoconductive and recent research also demonstrated the temperature dependence of the
photocurrent in the nanowires. They are also sensitive to blue and other near UV spectra which is same range of
activation wavelengths of most photosensitizers, and hence making them a good candidate for a potential PDT
monitoring probe. ZnO nanowires were fabricated on silicon substrates by vapor phase deposition using e-beam
evaporated gold as a catalyst. Control of the dimensions of the nanowires could be achieved by varying the dimensions
of the catalyst by means of e-beam evaporation process. Photoluminescence properties of ZnO nanowires were
investigated at UV and near UV wavelengths. Further, ZnO is also known for its antimicrobial properties, thereby ruling
out any possibility of bacterial infection because of the implanted probe. This study was done to compliment the
existing expertise of our research group in the design and fabrication of several nanowire based probes and
microsensors specifically for neuroelectronic and nanomedicine applications.
On the size-dependent behavior of the micro-wire in the micro-tensile test
Show abstract
Micro-wires have used widely in microelectronic devices. In order to support the high performance of microsystems, it is
important to measure the mechanical properties of the micro-wires. In this study, we measured the mechanical properties
of micro-wire to investigate the size effect behavior experimentally. Specimens used in this study are platinum micro-wires
that have various diameters such as 15, 25, 40, 50, 125, 200, and 250 &mgr;m. The platinum micro-wires with the
purity of 99.99 % were annealed to remove the residual stress. We carried out the tensile test to measure the mechanical
properties using the nanoUTM and TYTRON 250. Many researches in micro scale structures have shown that the
deformation is dependent on the size of specimen as well as grain size. To evaluate the size effect, we focused on the
relation between the strength and the specimen diameter. Our result shows that the strength of the specimen changes as
its diameter changes. We are trying to investigate micro-structure of the specimen such as grain boundary to explain this
size-dependent behavior.
Wideband microwave absorber design using micro and nanomaterials
Show abstract
In this paper, we present the design and experimental results of wide-band composite microwave absorber fabricated
using thermoplastic polyurethane, carbon fibers, glass microballoons, micro and nano size magnetic materials. Ni-Zn
ferrite and carbonyl iron powders of nano and micrometer size particles were used along with carbon fibers and
microbaloons for the development of the absorber. It is found that both Ni-Zn ferrite and carbonyl iron powders and
their ratio in the composite plays critical role in the absorber performance. Measured results show that a reflectivity
reduction of 15 dB from 5 to 18 GHz is possible using this composite absorber.
Design and fabrication of OTFT based flexible piezoelectric sensor
Show abstract
Design and fabrication of Organic Thin Film Transistor (OTFT) based miniaturized piezoelectric sensor is presented in
this investigation. The device is fabricated on flexible polyethylene naphthalate (PEN) film, using the small-molecule
hydrocarbon pentacene as the semiconductor layer and solution-processed polyvinylphenol as the gate dielectric. Field
effect mobility of the OTFT is greater than 0.01 cm2/Vs, Ion/Ioff current ratio greater than 105. The piezoelectric polymer,
Polyvinylidene Fluoride (PVDF) is used as the sensor layer that is attached over the extended gate metal electrode of the
OTFT. OTFT, which is in close proximity with sensor, serves as the amplifier to amplify the signal generated by
piezoelectric sensor.