Dr. Donald J. Leo Profile

Dr. Donald J. Leo

Dean at Univ of Georgia

SPIE Involvement:

Conference Program Committee | Editor | Author

Publications (95)

Proceedings Article | 17 April 2017 Presentation + Paper

A 3D printing method for droplet-based biomolecular materials

Elio Challita, Joseph Najem, Eric Freeman, Donald Leo

Proc. SPIE. 10167, Nanosensors, Biosensors, Info-Tech Sensors and 3D Systems 2017

KEYWORDS: MATLAB, Proteins, Tissues, Cameras, Electrodes, Glasses, 3D printing, Printing, Head, Excel

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Proceedings Article | 10 March 2014 Paper

Mechanosensitive droplet interface bilayer networks

Eric Freeman, Michael Philen, Donald Leo

Proc. SPIE. 9058, Behavior and Mechanics of Multifunctional Materials and Composites 2014

KEYWORDS: Biosensing, Electrodes, Molecules, Interfaces, Adsorption

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Proceedings Article | 8 April 2013 Paper

Biomolecular hydrogel-based lipid bilayer array system

Joseph Najem, Alex Edgerton, Donald Leo

Proc. SPIE. 8686, Bioinspiration, Biomimetics, and Bioreplication 2013

KEYWORDS: Fabrication, Lithography, Polyurethane, Lenses, Electrodes, Glasses, Ultraviolet radiation, Interfaces, Silver, Photomasks

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Proceedings Article | 8 April 2013 Paper

Using cellular energy conversion and storage mechanics for bio-inspired energy harvesting

Eric Freeman, Michael Philen, Donald Leo

Proc. SPIE. 8686, Bioinspiration, Biomimetics, and Bioreplication 2013

KEYWORDS: Proteins, Mechanics, Electrodes, Molecules, Ions, Transmission electron microscopy, Energy harvesting, Biomimetics, Chlorine, Systems modeling

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Proceedings Article | 3 April 2013 Paper

Network modeling of membrane-based artificial cellular systems

Eric Freeman, Michael Philen, Donald Leo

Proc. SPIE. 8689, Behavior and Mechanics of Multifunctional Materials and Composites 2013

KEYWORDS: Mathematical modeling, Proteins, Capacitors, Mechanics, Interfaces, Ions, Diffusion, Neodymium, Systems modeling, Information operations

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Proceedings Article | 4 April 2012 Paper

Formation, encapsulation, and validation of membrane-based artificial hair cell sensors

Kevin Garrison, Stephen Sarles, Donald Leo

Proc. SPIE. 8339, Bioinspiration, Biomimetics, and Bioreplication 2012

KEYWORDS: Infrared sensors, Sensors, Electrodes, Ions, Data acquisition, Capacitance, Aluminum, Ear, Analytical research, Surface conduction electron emitter displays

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Proceedings Article | 4 April 2012 Paper

Biologically inspired highly efficient buoyancy engine

Barbar Akle, Wassim Habchi, Rita Abdelnour, John Blottman, Donald Leo

Proc. SPIE. 8339, Bioinspiration, Biomimetics, and Bioreplication 2012

KEYWORDS: Modulation, Sensors, Electrodes, Water, Ions, Silver, Organisms, Distributed computing, Bladder, Ion exchange

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Undersea distributed networked sensor systems require a miniaturization of platforms and a means of both spatial and temporal persistence. One aspect of this system is the necessity to modulate sensor depth for optimal positioning and station-keeping. Current approaches involve pneumatic bladders or electrolysis; both require mechanical subsystems and consume significant power. These are not suitable for the miniaturization of sensor platforms. Presented in this study is a novel biologically inspired method that relies on ionic motion and osmotic pressures to displace a volume of water from the ocean into and out of the proposed buoyancy engine. At a constant device volume, the displaced water will alter buoyancy leading to either sinking or floating. The engine is composed of an enclosure sided on the ocean's end by a Nafion ionomer and by a flexible membrane separating the water from a gas enclosure. Two electrodes are placed one inside the enclosure and the other attached to the engine on the outside. The semi-permeable membrane Nafion allows water motion in and out of the enclosure while blocking anions from being transferred. The two electrodes generate local concentration changes of ions upon the application of an electrical field; these changes lead to osmotic pressures and hence the transfer of water through the semi-permeable membrane. Some aquatic organisms such as pelagic crustacean perform this buoyancy control using an exchange of ions through their tissue to modulate its density relative to the ambient sea water. In this paper, the authors provide an experimental proof of concept of this buoyancy engine. The efficiency of changing the engine's buoyancy is calculated and optimized as a function of electrode surface area. For example electrodes made of a 3mm diameter Ag/AgCl proved to transfer approximately 4mm3 of water consuming 4 Joules of electrical energy. The speed of displacement is optimized as a function of the surface area of the Nafion membrane and its thickness. The 4mm3 displaced volume obtained with the Ag/AgCl electrodes required approximately 380 seconds. The thickness of the Nafion membrane is 180μm and it has an area of 133mm3.

Proceedings Article | 4 April 2012 Paper

A bio-inspired bell kinematics design of a jellyfish robot using ionic polymer metal composites actuators

Joseph Najem, Donald Leo

Proc. SPIE. 8340, Electroactive Polymer Actuators and Devices (EAPAD) 2012

KEYWORDS: Actuators, Gold, Electrodes, Polymers, Metals, Composites, Robotics, Kinematics, Biomimetics, Prototyping

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Proceedings Article | 4 April 2012 Paper

Study of the effects of ionic liquids on lipid bilayers

Taylor Young, Stephen Sarles, Tianyu Wu, Matthew Green, Timothy Long, Donald Leo

Proc. SPIE. 8339, Bioinspiration, Biomimetics, and Bioreplication 2012

KEYWORDS: Microscopes, Sensors, Electrodes, Water, Ultraviolet radiation, Interfaces, Ions, Chemistry, Capacitance, Liquids

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Proceedings Article | 4 April 2012 Paper

A bio-inspired aquatic flow sensor using an artificial cell membrane

Preston Pinto, Kevin Garrison, Donald Leo, Stephen Sarles

Proc. SPIE. 8339, Bioinspiration, Biomimetics, and Bioreplication 2012

KEYWORDS: Polyurethane, Sensors, Electrodes, Skin, Interfaces, Organisms, Control systems, Biomimetics, Aluminum, Receptors

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Proceedings Article | 29 March 2011 Paper

Design and development of bio-inspired underwater jellyfish like robot using ionic polymer metal composite (IPMC) actuators

Barbar Akle, Joseph Najem, Donald Leo, John Blottman

Proc. SPIE. 7976, Electroactive Polymer Actuators and Devices (EAPAD) 2011

KEYWORDS: Actuators, Gold, Electrodes, Polymers, Metals, Composites, Ions, Robotics, Transducers, Liquids

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Proceedings Article | 29 March 2011 Paper

Cell-inspired electroactive polymer materials incorporating biomolecular materials

Stephen Sarles, Donald Leo

Proc. SPIE. 7976, Electroactive Polymer Actuators and Devices (EAPAD) 2011

KEYWORDS: Proteins, Polymers, Molecules, Interfaces, Resistance, Capacitance, Solids, Sensing systems, Molecular biology, Electroactive polymers

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Proceedings Article | 23 March 2011 Paper

Modeling and optimization of IPMC actuator for autonomous jellyfish vehicle (AJV)

Keyur Joshi, Barbar Akle, Donald Leo, Shashank Priya

Proc. SPIE. 7975, Bioinspiration, Biomimetics, and Bioreplication

KEYWORDS: Actuators, Electrodes, Polymers, Metals, Finite element methods, Optical simulations, Optimization (mathematics), Thermal modeling, Liquids, Polymeric actuators

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Proceedings Article | 23 March 2011 Paper

Hair cell sensing with encapsulated interface bilayers

Stephen Sarles, Donald Leo

Proc. SPIE. 7975, Bioinspiration, Biomimetics, and Bioreplication

KEYWORDS: Polyurethane, Sensors, Electrodes, Video, Molecules, Interfaces, Resistance, Capacitance, Motion measurement, Liquids

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Proceedings Article | 23 March 2011 Paper

Single channel conductance modeling of the peptide alamethicin in synthetically formed bilayers

M. Austin Creasy, Donald Leo

Proc. SPIE. 7975, Bioinspiration, Biomimetics, and Bioreplication

KEYWORDS: Proteins, Data modeling, Electrodes, Interfaces, Ions, Picosecond phenomena, Intelligence systems, Circuit switching, Statistical modeling, Systems modeling

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Proceedings Article | 12 April 2010 Paper

Physical encapsulation and controlled assembly of lipid bilayers within flexible substrates

Stephen Sarles, Donald Leo

Proc. SPIE. 7643, Active and Passive Smart Structures and Integrated Systems 2010

KEYWORDS: Microfluidics, Proteins, Electrodes, Molecules, Interfaces, Silicon, Capacitance, Semiconducting wafers, Molecular self-assembly, Plasma

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Proceedings Article | 10 April 2010 Paper

Modeling bilayer systems as electrical networks

M. Austin Creasy, Donald Leo

Proc. SPIE. 7643, Active and Passive Smart Structures and Integrated Systems 2010

KEYWORDS: Proteins, Capacitors, Data modeling, Molecules, Interfaces, Ions, Capacitance, Resistors, Circuit switching, Systems modeling

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Proceedings Article | 31 March 2010 Paper

Finite element modeling of the electromechanical coupling in ionic polymer transducers

Barbar Akle, Wassim Habchi, Thomas Wallmersperger, Donald Leo

Proc. SPIE. 7644, Behavior and Mechanics of Multifunctional Materials and Composites 2010

KEYWORDS: Actuators, Calibration, Electrodes, Polymers, Particles, Dielectrics, Ions, Numerical simulations, Transducers, Finite element methods

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Proceedings Article | 7 April 2009 Paper

Incorporation and characterization of biological molecules in droplet-interface bilayer networks for novel active systems

Stephen Sarles, Pegah Ghanbari Bavarsad, Donald Leo

Proc. SPIE. 7288, Active and Passive Smart Structures and Integrated Systems 2009

KEYWORDS: Proteins, Electrodes, Molecules, Interfaces, Ions, Resistance, Molecular biology, Dielectric spectroscopy, Electrical breakdown, Molecular self-assembly

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Proceedings Article | 6 April 2009 Paper

Electromechanical performance and membrane stability of novel ionic polymer transducers constructed in the presence of ionic liquids

Andrew Duncan, Donald Leo, Timothy Long, Barbar Akle, Jong Park, Robert Moore

Proc. SPIE. 7287, Electroactive Polymer Actuators and Devices (EAPAD) 2009

KEYWORDS: Actuators, Scattering, Polymers, Glasses, X-rays, Resistance, Laser scattering, Transducers, Electroactive polymers, Liquids

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Ionic polymer transducers (IPT) are a class of devices that leverage electroactive polymers (EAP), specifically electrolyte-swollen ionomeric membranes, to perform energy conversions. Energy transformation from input to output is referred to as transduction and occurs between the electrical and mechanical domains. The present study expands on IPT investigations with a novel series of sulfonated polysulfones (sBPS), with specific interest in the effect of polymer topology on actuator performance. A hydrophilic ionic liquid was combined with a series of sBPS through a casting method to create hydrated membranes that contained target uptakes (f) of the diluent. The ionic liquid's hydrophilic, yet organic nature raised the issue of its degree of compatibility and miscibility with the microphase separated domains of the host ionomeric membrane. Initial studies of the ionomer - ionic liquid morphology were performed with synchrotron small angle X-ray scattering (SAXS). The effective plasticization of the membranes was identified with dynamic mechanical analysis (DMA) in terms of varied storage modulus and thermal transitions with ionic liquid uptake. Electrical impedance spectroscopy (EIS) was employed to quantify the changes in ionic conductivity for each sBPS ionomer across a range of uptake. Combined results from these techniques implied that the presence of large amounts of ionic liquid swelled the hydrophilic domains of the ionomer and greatly increased the ionic conductivity. Decreases in storage modulus and the glass transition temperature were proportional to one another but of a lesser magnitude than changes in conductivity. The present range of ionic liquid uptake for sBPS was sufficient to identify the critical uptake (f_c) for three of the four ionomers in the series. Future work to construct IPTs with these components will use the critical uptake as a minimum allowable content of ionic liquid to optimize the balance of electrical and mechanical properties for the device components.

Proceedings Article | 6 April 2009 Paper

Forced and free displacement characterization of ionic polymer transducers

Barbar Akle, Andrew Duncan, Etienne Akle, Thomas Wallmersperger, Donald Leo

Proc. SPIE. 7287, Electroactive Polymer Actuators and Devices (EAPAD) 2009

KEYWORDS: Actuators, Lithium, Electrodes, Polymers, Transducers, Aluminum, Cesium, Temperature metrology, Liquids, Polymeric actuators

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Ionic polymer transducers (IPT), sometimes referred to as artificial muscles, are known to generate a large bending strain and a moderate stress at low applied voltages (<5V). Recently Akle and Leo[1] reported extensional actuation in ionic polymer transducers. In this study, extensional IPTs are characterized under forced and free displacement boundary condition as a function of transducer architecture. The electrode thickness is varied from 10 μm up to 40 μm while three extensional actuators with Lithium, Cesium, and tetraethylammonium (TEA) mobile cations are characterized. Three fixtures are built in order to characterize the extensional actuation response. The first fixture measures the free displacement of an IPT sample sandwiched between two aluminum plates glued using the electrically conductive silver paste. In the second fixture a spring is compressed against the test sample with variable amounts to generate different levels of pre-stress and prevents the bending of the IPT. In the third fixture dead weights are placed on top of the sample in order to prevent bending. In the spring loaded fixture a thermocouple is placed in the proximity of the actuator and temperature is measured. The different transducers are characterized using a step voltage input and an alternating current (AC) sine wave input. The step input resulted in a logarithmic rise like displacement curve, while the low frequency (<0.1 Hz) AC excitation generated a sine wave displacement response with a strong first harmonic. The high frequency AC excitation generated a response similar to that of the step input. Comparing the measured temperature for step and AC response demonstrated that the sample is heating up when exited with a high frequency signal; which is leading to the expansion of the sample. Initial experimental results demonstrate a strong correlation between electrode architecture and the peak strain response. Strains on the order of 2% are observed with air stable ionic liquid based transducers. A correlation between the strain and charge buildup in the polymer is also characterized. Cesium (Cs) mobile cation outperformed all other tested mobile charges, while Potassium displaced the least. Keywords: Ionic Polymers, Transducer, Actuator, Electroactive Polymer, Extensional Actuator.

Proceedings Article | 1 April 2009 Paper

Droplet interface bilayer characteristics formed over a synthetic porous substrate

M. Austin Creasy, Donald Leo

Proc. SPIE. 7291, Nanosensors, Biosensors, and Info-Tech Sensors and Systems 2009

KEYWORDS: Proteins, Capacitors, Data modeling, Electrodes, Molecules, Interfaces, Resistance, Capacitance, Resistors, Tolerancing

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Proceedings Article | 18 April 2008 Paper

Characterization of porous substrates for biochemical energy conversion devices

Vishnu Baba Sundaresan, Stephen Andrew Sarles, Donald Leo

Proc. SPIE. 6928, Active and Passive Smart Structures and Integrated Systems 2008

KEYWORDS: Microelectromechanical systems, Proteins, Capacitors, Molecules, Silicon, Coating, Resistance, Capacitance, Dielectric spectroscopy, Prototyping

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Proceedings Article | 10 April 2008 Paper

Optimization of active electrodes for novel ionomer-based ionic polymer transducers

Andrew Duncan, Stephen Sarles, Donald Leo, Timothy Long, Barbar Akle, Matthew Bennett

Proc. SPIE. 6927, Electroactive Polymer Actuators and Devices (EAPAD) 2008

KEYWORDS: Data modeling, Electrodes, Polymers, Particles, Interfaces, Resistance, Transducers, Circuit switching, Electromechanical design, Liquids

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Proceedings Article | 10 April 2008 Paper

Plastic Muscles as lightweight, low voltage actuators and sensors

Matthew Bennett, Donald Leo, Andrew Duncan

Proc. SPIE. 6927, Electroactive Polymer Actuators and Devices (EAPAD) 2008

KEYWORDS: Actuators, Sensors, Electrodes, Polymers, Metals, Platinum, Capacitance, Transducers, Palladium, Liquids

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Proceedings Article | 10 April 2008 Paper

Micro deposition method: a novel fabrication method for ionic polymer metallic composites

David Griffiths, Vishnu Baba Sundaresan, Barbar Akle, Pavlos Vlachos, Don Leo

Proc. SPIE. 6927, Electroactive Polymer Actuators and Devices (EAPAD) 2008

KEYWORDS: Fabrication, Actuators, Microfluidics, Electrodes, Polymers, Composites, Head, Transducers, Deposition processes, Ruthenium

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Proceedings Article | 10 April 2008 Paper

A correlation between extensional displacement and architecture of ionic polymer transducers

Barbar Akle, Andrew Duncan, Donald Leo

Proc. SPIE. 6927, Electroactive Polymer Actuators and Devices (EAPAD) 2008

KEYWORDS: Actuators, Gold, Data modeling, Electrodes, Polymers, Transducers, Aluminum, Electroactive polymers, Liquids, Polymeric actuators

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Ionic polymer transducers (IPT), sometimes referred to as artificial muscles, are known to generate a large bending strain and a moderate stress at low applied voltages (<5V). Bending actuators have limited engineering applications due to the low forcing capabilities and the need for complicated external devices to convert the bending action into rotating or linear motion desired in most devices. Recently Akle and Leo reported extensional actuation in ionic polymer transducers. In this study, extensional IPTs are characterized as a function of transducer architecture. In this study 2 actuators are built and there extensional displacement response is characterized. The transducers have similar electrodes while the middle membrane in the first is a Nafion / ionic liquid and an aluminum oxide - ionic liquid in the second. The first transducer is characterized for constant current input, voltage step input, and sweep voltage input. The model prediction is in agreement in both shape and magnitude for the constant current experiment. The values of α and β used are within the range of values reported in Akle and Leo. Both experiments and model demonstrate that there is a preferred direction of applying the potential so that the transducer will exhibit large deformations. In step response the model well predicted the negative potential and the early part of the step in the positive potential and failed to predict the displacement after approximately 180s has elapsed. The model well predicted the sweep response, and the observed 1st harmonic in the displacement further confirmed the existence of a quadratic in the charge response. Finally the aluminum oxide based transducer is characterized for a step response and compared to the Nafion based transducer. The second actuator demonstrated electromechanical extensional response faster than that in the Nafion based transducer. The Aluminum oxide based transducer is expected to provide larger forces and hence larger energy density.

Proceedings Article | 2 April 2008 Paper

High surface area electrodes in ionic polymer transducers: numerical and experimental investigations of the chemo-electric behavior

Barbar Akle, Thomas Wallmersperger, Etienne Akle, Donald Leo

Proc. SPIE. 6929, Behavior and Mechanics of Multifunctional and Composite Materials 2008

KEYWORDS: Data modeling, Electrodes, Polymers, Metals, Particles, Ions, Scanning electron microscopy, Transducers, Finite element methods, Computer architecture

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Proceedings Article | 2 April 2008 Paper

Self-healing of bilayer lipid membranes formed over silicon substrates with a single pore

M. Austin Creasy, David Hopkinson, Donald Leo

Proc. SPIE. 6929, Behavior and Mechanics of Multifunctional and Composite Materials 2008

KEYWORDS: Data modeling, Electrodes, Composites, Silicon, Resistance, Capacitance, Intelligence systems, Failure analysis, Electrical breakdown, Lead

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Proceedings Article | 11 October 2007 Paper

Study of supported bilayer lipid membranes for use in chemo-electric energy conversion via active proton transport

Stephen Sarles, Vishnu Sundaresan, Donald Leo

Proc. SPIE. 6769, Nanosensing: Materials, Devices, and Systems III

KEYWORDS: Proteins, Sensors, Electrodes, Molecules, Ions, Resistance, Signal processing, Acquisition tracking and pointing, Biological research, Resistors

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Bilayer lipid membranes (BLMs) have been studied extensively due to functional and structural similarities to cell membranes, fostering research to understand ion-channel protein functions, measure bilayer mechanical properties, and identify self-assembly mechanisms. BLMs have traditionally been formed across single pores in substrates such as PTFE (Teflon). The incorporation of ion-channel proteins into the lipid bilayer enables the selective transfer of ions and fluid through the BLM. Processes of this nature have led to the measurement of ion current flowing across the lipid membrane and have been used to develop sensors that signal the presence of a particular reactant (glucose, urea, penicillin), improve drug recognition in cells, and develop materials capable of creating chemical energy from light. Recent research at Virginia Tech has shown that the incorporation of proton transporters in a supported BLM formed across an array of pores can convert chemical energy available in the adenosine triphosphate (ATP) into electricity. Experimental results from this work show that the system-named Biocell-is capable of developing 2µW/cm² of membrane area with 15μl of ATPase. Efforts to increase the power output and conversion efficiency of this process while moving toward a packaged device present a unique engineering problem. The bilayer, as host to the active proton transporters, must therefore be formed evenly across a porous substrate, remain stable and yet fluid-like for protein interaction, and exhibit a large seal resistance. This article presents the ongoing work to characterize the Biocell using impedance analysis. Electrical impedance spectroscopy (EIS) is used to study the effect of adding ATPase proteins to POPS:POPE bilayer lipid membranes and correlate structural changes evident in the impedance data to the energy-conversion capability of various partial and whole Biocell assemblies. The specific membrane resistance of a pure BLM drops from 40-120kΩ•cm² to only a few hundred Ω•cm² upon reconstitution of ATPase proteins. Power characterization indicates that ATP hydrolysis may result in charging of the silver-silver chloride electrodes.

Proceedings Article | 27 April 2007 Paper

Chemoelectrical energy conversion of adenosine triphosphate

Vishnu Baba Sundaresan, Stephen Andrew Sarles, Donald Leo

Proc. SPIE. 6525, Active and Passive Smart Structures and Integrated Systems 2007

KEYWORDS: Potassium, Proteins, Electrodes, Ions, Resistance, Capacitance, Acquisition tracking and pointing, Sodium, Prototyping, Plasma

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Proceedings Article | 27 April 2007 Paper

Adaptive positive position feedback for energy absorption in acoustic cavities

M. Austin Creasy, Donald Leo, Kevin Farinholt

Proc. SPIE. 6525, Active and Passive Smart Structures and Integrated Systems 2007

KEYWORDS: Actuators, Data modeling, Control systems, Linear filtering, Scanning probe lithography, Acoustics, Systems modeling, Device simulation, Temperature metrology, Absorption

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Proceedings Article | 25 April 2007 Paper

Evaluating the mechanical integrity of bilayer lipid membranes using a high-precision pressurization system

David Hopkinson, Donald Leo

Proc. SPIE. 6526, Behavior and Mechanics of Multifunctional and Composite Materials 2007

KEYWORDS: Actuators, Microfluidics, Statistical analysis, Custom fabrication, Data modeling, Manufacturing, Transducers, Failure analysis, Statistical modeling, Lead

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Proceedings Article | 18 April 2007 Paper

Development of ionic polymer transducers as flow shear stress sensors: effects of electrode architecture

David Griffiths, Justin Dominic, Barbar Akle, Pavlos Vlachos, Donald Leo

Proc. SPIE. 6529, Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2007

KEYWORDS: Sensors, Calibration, Electrodes, Polymers, Resistance, Amplifiers, Capacitance, Transducers, Resistors, Polymeric sensors

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Proceedings Article | 18 April 2007 Paper

Monte Carlo simulation of ion transport of the high strain ionomer with conducting powder electrodes

Xingxi He, Donald Leo

Proc. SPIE. 6523, Modeling, Signal Processing, and Control for Smart Structures 2007

KEYWORDS: Optical spheres, Electrodes, Polymers, Ions, 3D modeling, Monte Carlo methods, Transducers, Finite element methods, Polymeric sensors, Polymeric actuators

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The transport of charge due to electric stimulus is the primary mechanism of actuation for a class of polymeric active materials known as ionomeric polymer transducers (IPT). At low frequency, strain response is strongly related to charge accumulation at the electrodes. Experimental results demonstrated using conducting powder, such as single-walled carbon nanotubes (SWNT), polyaniline (PANI) powders, high surface area RuO₂, carbon black electrodes etc. as an electrode increases the mechanical deformation of the IPT by increasing the capacitance of the material. In this paper, Monte Carlo simulation of a two-dimensional ion hopping model has been built to describe ion transport in the IPT. The shape of the conducting powder is assumed to be a sphere. A step voltage is applied between the electrodes of the IPT, causing the thermally-activated hopping between multiwell energy structures. Energy barrier height includes three parts: the energy height due to the external electric potential, intrinsic energy, and the energy height due to ion interactions. Finite element method software-ANSYS is employed to calculate the static electric potential distribution inside the material with the powder sphere in varied locations. The interaction between ions and the electrodes including powder electrodes is determined by using the method of images. At each simulation step, the energy of each cation is updated to compute ion hopping rate which directly relates to the probability of an ion moving to its neighboring site. Simulation ends when the current drops to constant zero. Periodic boundary conditions are applied when ions hop in the direction perpendicular to the external electric field. When an ion is moved out of the simulation region, its corresponding periodic replica enters from the opposite side. In the direction of the external electric field, parallel programming is achieved in C augmented with functions that perform message-passing between processors using Message Passing Interface (MPI) standard. The effects of conducting powder size, locations and amount are discussed by studying the stationary charge density plots and ion distribution plots.

Proceedings Article | 5 April 2007 Paper

Development and modeling of novel extensional ionic polymer transducers

Barbar Akle, Thomas Wallmersperger, Donald Leo

Proc. SPIE. 6524, Electroactive Polymer Actuators and Devices (EAPAD) 2007

KEYWORDS: Actuators, Gold, Data modeling, Electrodes, Polymers, Ions, Transducers, Motion models, Liquids, Polymeric actuators

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Proceedings Article | 4 April 2007 Paper

Chemo-electric characterization and modeling of the high surface area electrodes in ionic polymer transducers

Thomas Wallmersperger, Barbar Akle, Etienne Akle, Donald Leo

Proc. SPIE. 6524, Electroactive Polymer Actuators and Devices (EAPAD) 2007

KEYWORDS: Gold, Data modeling, Electrodes, Polymers, Particles, Dielectrics, Ions, Numerical simulations, Transducers, Spherical lenses

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Proceedings Article | 6 April 2006 Paper

Investigation on micro-patterned gold-plated polymer substrate for a micro hydraulic actuator

Vishnu Baba Sundaresan, Barbar Akle, Donald Leo

Proc. SPIE. 6170, Smart Structures and Materials 2006: Active Materials: Behavior and Mechanics

KEYWORDS: Actuators, Gold, Microfluidics, Proteins, Polymers, Molecules, Ions, Resistance, Head, Polymeric actuators

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Plants have the ability to develop large mechanical force from chemical energy available with bio-fuels. The energy released by the cleavage of a terminal phosphate ion during the hydrolysis of a bio-fuel assists the transport of ions and fluids in cellular homeostasis. Materials that develop pressure and hence strain similar to the response of plants to an external stimuli are classified as nastic materials. This new class of actuators use protein transporters as functional units to move species and result in deformation [Leo et al 2005 (Proceedings of IMECE - 06)]. The ion transporters are hydrocarbons which are formed across the cellular membranes. The membranes that house the ion transporters are aggregates of phospholipids rigidized by cytoskeleton. Reconstituting these nano-machines on a harder matrix is quintessential to build a functional device. Artificial phospholipid membranes or Biliayer lipid membranes (BLM) have poor structural integrity and do not adhere to most surfaces. Patterned arrays of pores made on Poly-propylene glycol-diacrylate (PPG-DA) substrate, a photo curable polymer was made available to us for initial design iterations for an actuator. Hydrophobicity of PPG-DA posed initial problems to support a BLM. We modified the surface of micropatterned PPG-DA membrane by gold plating it. The surface of the porous PPG-DA membranes was plated with gold (Au). A 10nm seeding layer of Au was sputtered on the surface of the membrane. Further gold was reduced onto the sputtered gold surface [Supriya et al(Langmuir 2004, 20, 8870-8876)] by suspending the samples in a solution of hydroxylamine and Hydrogen tetrachloroaurate(III) trihydrate [HAuCl4.3H2O]. This reduction process increased the thickness of the gold, enhanced its adhesion to the PPG-DA substrate and improved the shapes of the pores. This surface modification of PPG-DA helped us form stable BLM with 1-Palmitoyl-2-Oleoyl-sn-Glycero-3- [Phospho-L-Serine] (Sodium Salt) (POPS), 1-Palmitoyl-2-Oleoyl-sn-Glycero- 3-Phosphoethanolamine (POPE) lipids. The observed ionic resistance of the BLM remained stable and sustained 4 mm water column for the the four hours observation period. This article describes the procedure we adopted to modify the PPG-DA substrate, form a BLM and the procedure to quantify the stability of the BLM formed with -amine and -thiol head groups in the lipids.

Proceedings Article | 6 April 2006 Paper

Failure pressure of bilayer lipid membranes

David Hopkinson, Raffaella De Vita, Donald Leo

Proc. SPIE. 6170, Smart Structures and Materials 2006: Active Materials: Behavior and Mechanics

KEYWORDS: Actuators, Data modeling, Polymers, Molecules, Resistance, Biomimetics, Solids, Polymer thin films, Molecular self-assembly, Protactinium

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Proceedings Article | 6 April 2006 Paper

Physics of transduction in ionic liquid-swollen Nafion membranes

Matthew Bennett, Donald Leo

Proc. SPIE. 6170, Smart Structures and Materials 2006: Active Materials: Behavior and Mechanics

KEYWORDS: Actuators, FT-IR spectroscopy, Lithium, Electrodes, Polymers, Ions, Transducers, Sodium, Electromagnetic coupling, Liquids

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Proceedings Article | 5 April 2006 Paper

Active rigidization of carbon-fiber reinforced polymer composites for ultra-lightweight space structures

Stephen Sarles, Donald Leo

Proc. SPIE. 6173, Smart Structures and Materials 2006: Smart Structures and Integrated Systems

KEYWORDS: Carbon, Polymers, Glasses, Particles, Composites, Control systems, Thermal analysis, Feedback control, Fiber coatings, Temperature metrology

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An active approach for initiating rigidization in carbon-fiber reinforced polymer (CFRP) thermosets links controllable mechanical stiffening to inherent electrical resistivity. With direct applications toward the rigidization of ultra-lightweight, inflatable space structures, temperature-controlled resistive heating is used to create oncommand rigidization. As required by the on-orbit conditions in space, flexible, rigidizable structures demand stable and space-survivable materials that incorporate techniques for providing shape control and structural stiffening. Methods currently employed to achieve a mechanical hardening include many passive techniques: UV curing, sub-T_g hardening, and hydro-gel evaporation. The benefits of a passive system (simplicity, energy efficiency) are offset by their inherent lack of control, which can lead to long curing times and weak spots due to uneven curing. In efforts to significantly reduce the transition time of the composite from a structurally-vulnerable state to a fully-rigidized shape and to increase control of the curing process, an active approach is taken. Specifically, temperature-controlled internal resistive heating initiates thermoset curing in a coated carbon fiber composite to form an electrically-controlled, thermally-activated material. Through controlled heating, this research examines how selective temperature control can be used to prescribe matrix consolidation and material rigidization on two different thermosetting resins, U-Nyte Set 201A and 201B. Feedback temperature control, based on a PID control algorithm, was applied to the process of resistive heating. Precise temperature tracking (less than 1.1°C RMS or ±3.3% error) was achieved for controlled sample heating. Using samples of the thermoset-coated carbon-fiber tow, composite hardening through resistive heating occurred in 24 minutes and required roughly 1 W-hr/inch of electrical energy. The rigidized material was measured to be 14-21 times stiffer in bending than the uncured material. In addition, the cure completion of the resin was measured through differential scanning calorimetry (DSC).

Proceedings Article | 27 March 2006 Paper

Dynamic modeling of the nonlinear response of ionic polymer actuators

Curt Kothera, Donald Leo

Proc. SPIE. 6166, Smart Structures and Materials 2006: Modeling, Signal Processing, and Control

KEYWORDS: Actuators, Data modeling, Polymers, Complex systems, Distortion, Solids, Velocity measurements, Nonlinear response, Systems modeling, Polymeric actuators

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Proceedings Article | 27 March 2006 Paper

Variational modeling of ionic polymer plate structures

Miles Buechler, Donald Leo

Proc. SPIE. 6166, Smart Structures and Materials 2006: Modeling, Signal Processing, and Control

KEYWORDS: Data modeling, Electrodes, Polymers, Matrices, Dielectrics, Manufacturing, Data centers, Motion models, Ferroelectric polymers, Liquids

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Proceedings Article | 27 March 2006 Paper

Monte Carlo simulation of ion transport of high strain ionomeric with cluster morphology

Xingxi He, Donald Leo

Proc. SPIE. 6166, Smart Structures and Materials 2006: Modeling, Signal Processing, and Control

KEYWORDS: Lithium, Scattering, Electrodes, Polymers, Ions, Macromolecules, 3D modeling, Monte Carlo methods, Transducers, Ion channels

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Proceedings Article | 22 March 2006 Paper

Protein-based microhydraulic transport for controllable actuation

Vishnu Baba Sundaresan, Donald Leo

Proc. SPIE. 6168, Smart Structures and Materials 2006: Electroactive Polymer Actuators and Devices (EAPAD)

KEYWORDS: Actuators, Microfluidics, Proteins, Electrodes, Glasses, Ions, Capacitance, Acquisition tracking and pointing, Silicate glass, Lead

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Plants have the ability to develop large mechanical force from chemical energy available with bio-fuels. The energy released by the cleavage of a terminal phosphate ion during the hydrolysis of a bio- fuel assists the transport of ions and fluids in cellular homeostasis. Materials that develop pressure and hence strain similar to the response of plants to an external stimuli are classified as nastic materials. Calculations for controlled actuation of an active material inspired by biological transport mechanism demonstrated the feasibility of developing such a material with actuation energy densities on the order of 100 kJ/m³. The mathematical model for a simplified proof of concept actuator referred to as micro hydraulic actuator uses ion transporters extracted from plants reconstituted on a synthetic bilayer lipid membrane (BLM). Thermodynamic model of the concept actuator predicted the ability to develop 5 percent normalized deformation in thickness of the micro- hydraulic actuator. Controlled fluid transport through AtSUT4 (Proton-sucrose co-transporter from Arabidopsis thaliana) reconstituted on a 1-Palmitoyl-2-Oleoyl-sn-Glycero-3-[Phospho-L- Serine] (Sodium Salt) (POPS), 1-Palmitoyl-2-Oleoyl-sn-Glycero-3- Phosphoethanolamine (POPE) BLM on a porous lead silicate glass plate (50μm with 61μm pitch) was driven by proton gradient. Bulk fluid flux of 1.2 μl/min was observed for each microliter of AtSUT4 transporter suspension (16.6 mg/ml in pH7.0 medium) reconstituted on the BLM. The flux rate is observed to be dependent on the concentration of sucrose present in pH4 buffer. Flux rate of 10 μl/min is observed for 5 mM sucrose in the first 10 minutes. The observed flux scales linearly with BLM area and the amount of proteins reconstituted on the lipid membrane. This article details the next step in the development of the micro hydraulic actuator - fluid transport driven by exergonic Adenosine triphosphate (ATP) hydrolysis reaction in the presence of ATP-phosphohydrolase (red beet ATP-ase) enzyme in the reconstituted bilayer.

Proceedings Article | 15 March 2006 Paper

Reliability of high-strain ionomeric polymer transducers fabricated using the novel direct assembly process

Barbar Akle, Saila Nawshin, Donald Leo

Proc. SPIE. 6168, Smart Structures and Materials 2006: Electroactive Polymer Actuators and Devices (EAPAD)

KEYWORDS: Actuators, Gold, Electrodes, Polymers, Reliability, Scanning electron microscopy, Humidity, Transducers, Liquids, Polymeric actuators

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Ionomeric polymer transducers have received considerable attention in the past several years. These actuators, sometimes referred to as artificial muscles, have the ability to generate large bending strain and moderate stress at low applied voltages. Typically, ionic polymer actuators are composed of Nafion-117 membranes with platinum electrodes and are saturated with water diluents. Recently the authors have developed a novel fabrication technique named the Direct Assembly Process (DAP), which allowed good control on electrode morphology and composition. The DAP consists of spraying two high surface area metal-ionomer electrodes on a Nafion membrane. A single- walled carbon nanotubes (SWNT) and ruthenium dioxide (RuO₂) hybrid electrode was sprayed on a Formamide hydrated Nafion-117 membrane using the DAP method. This transducer was shown to generate 9.4% peak-peak strain under the application of ±2V at a strain rate of 1%/sec. Furthermore using the DAP one is capable of incorporating several types of diluents in ionomeric polymer transducers. Transducers with ionic liquid diluents are demonstrated to operate in air for long periods of time. In this work we will present a reliability study of transducers fabricated using the DAP. Each transducer is tested under a frequency range of 0.2Hz to 1Hz, and a potential of ±1V to ±3V. Water hydrated transducers dehydrates and stop moving within 5 minutes while operating in air under ±2V. Transducers with Formamide diluents operate for 20,000 cycles under ±1.5V and 0.5Hz (around 11hrs), while they degrade in less than 3000 cycles under ±2V and 0.5Hz. Ionic liquid based transducers are demonstrated to operate in air for over 400,000 with little loss in performance, and over 1 million cycle with a loss of only 43%. Actuators with several electrode compositions are fabricated and a correlation between the reliability of ionic liquid-ionic polymer transducers and maximum strain will be presented. This correlation will be used to assess the adhesion between the high surface area electrodes and the Nafion membrane. SEM images of tested transducers will be presented.

Proceedings Article | 19 May 2005 Paper

Application of Monte Carlo simulations to the prediction of the effective elastic moduli of hydrated Nafion

Lisa Mauck Weiland, Emily Lada, Ralph Smith, Donald Leo

Proc. SPIE. 5757, Smart Structures and Materials 2005: Modeling, Signal Processing, and Control

KEYWORDS: Statistical analysis, Polymers, Matrices, Particles, Monte Carlo methods, Transducers, Intelligence systems, Scientific research, Mechanical engineering, Statistical modeling

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Proceedings Article | 19 May 2005 Paper

Characterization of the solvent-induced nonlinear response of ionic polymer actuators

Curt Kothera, Donald Leo

Proc. SPIE. 5757, Smart Structures and Materials 2005: Modeling, Signal Processing, and Control

KEYWORDS: Actuators, Data modeling, Polymers, Error analysis, Complex systems, Distortion, Nonlinear optics, Statistical modeling, Liquids, Polymeric actuators

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Proceedings Article | 16 May 2005 Paper

Electrical impedance modeling of ionic polymer transducers

Kevin Farinholt, Donald Leo

Proc. SPIE. 5761, Smart Structures and Materials 2005: Active Materials: Behavior and Mechanics

KEYWORDS: Lithium, Electrodes, Polymers, Ions, Transducers, Differential equations, Convolution, Motion models, Systems modeling, Astatine

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Proceedings Article | 16 May 2005 Paper

A variational model of ionomeric polymer actuators and sensors

Miles Buechler, Donald Leo

Proc. SPIE. 5760, Smart Structures and Materials 2005: Damping and Isolation

KEYWORDS: Actuators, Data modeling, Sensors, Polymers, Dielectrics, Transducers, Ferroelectric polymers, Systems modeling, Polymeric sensors, Polymeric actuators

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Proceedings Article | 16 May 2005 Paper

Switched-state control of a vibration isolation mount using ionomeric materials

Donald Leo, Juan Mejia-Ariza

Proc. SPIE. 5760, Smart Structures and Materials 2005: Damping and Isolation

KEYWORDS: Mathematical modeling, Polymers, Skin, Ceramics, Control systems, Platinum, Vibration control, Humidity, Motion models, Vibration isolation

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Materials that exhibit controllable modulus variations will enable new developments in applications in vibration suppression and shape change. In this paper we analyze a class of materials that exhibits reversible modulus variations due to solvent incorporation or removal. These materials, known as ionomeric polymers, have been shown previously to exhibit 20X changes in modulus depending on the hydration state of the material. A test fixture that allows a ionomeric polymer sample to be placed in a hydration controlled environment is developed. The Young's modulus of unplated materials and materials plated with metal is measured as a function of hydration level. A change of 2.56 and 3.89 times in modulus is obtained for the unplated and plated material, respectively. Experiments are performed to determine the ability to increase the stiffening rate of the polymer using applied electrical energy. Square input signals are applied to increase the elastic modulus of these materials. The rate of modulus change is higher or lower depending on the voltage amplitude and the forcing frequency of the input signal. Different kinds of solvents are used to control the modulus of the ionomer plated with platinum. Glycerol is the solvent with the highest modulus reduction (88.87%) and water is the smallest (67.71%). In addition, a test fixture consisting of a mass on a plate is built and modeled as moving-base. The change in stiffness is explored as a method to reduce unwanted vibration. The displacement transmissibility versus frequency is measured for water and acetonitrile solvents. The stiffness of Nafion 117 is computed when the solvents are applied and after they dry. The steady state response of the system is measured by applying a sinusoidal input signal. A forcing frequency of 94 Hz near the natural frequency is selected to produce a high amplitude. The displacement amplitude is reduced 5 times in 10 seconds after the application of the acetonitrile to the ionomeric polymer. These results demonstrate the basic feasibility of controlling the modulus in real time and quantify the time constants associated with hydration and dehydration of the material.

Proceedings Article | 16 May 2005 Paper

Chemo-mechanical model of biological membranes for actuation mechanisms

Vishnu-Baba Sundaresan, Donald Leo

Proc. SPIE. 5761, Smart Structures and Materials 2005: Active Materials: Behavior and Mechanics

KEYWORDS: Mathematical modeling, Actuators, Microfluidics, Mechanics, Molecules, Ions, Acquisition tracking and pointing, Biological research, Thermodynamics, Shape memory alloys

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Proceedings Article | 16 May 2005 Paper

Monte Carlo analysis of ionic polymers with cluster morphology

Lisa Mauck Weiland, Donald Leo

Proc. SPIE. 5761, Smart Structures and Materials 2005: Active Materials: Behavior and Mechanics

KEYWORDS: Lithium, Electrodes, Polymers, Dielectrics, Ions, Monte Carlo methods, Sodium, Motion models, Mechanical engineering, Spherical lenses

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Proceedings Article | 6 May 2005 Paper

Morphological and electromechanical characterization of ionic liquid/Nafion polymer composites

Matthew Bennett, Donald Leo

Proc. SPIE. 5759, Smart Structures and Materials 2005: Electroactive Polymer Actuators and Devices (EAPAD)

KEYWORDS: Potassium, Lithium, Polymers, X-rays, Composites, Ions, Transducers, Electromagnetic coupling, Cesium, Liquids

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Proceedings Article | 6 May 2005 Paper

Computational models of ionic transport and electromechanical transduction in ionomeric polymer transducers

Donald Leo, Kevin Farinholt, Thomas Wallmersperger

Proc. SPIE. 5759, Smart Structures and Materials 2005: Electroactive Polymer Actuators and Devices (EAPAD)

KEYWORDS: Data modeling, Mechanics, Electrodes, Polymers, Ions, Numerical simulations, Distortion, Computer simulations, Transducers, Systems modeling

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Proceedings Article | 6 May 2005 Paper

Ionic electroactive hybrid transducers

Barbar Akle, Matthew Bennett, Donald Leo

Proc. SPIE. 5759, Smart Structures and Materials 2005: Electroactive Polymer Actuators and Devices (EAPAD)

KEYWORDS: Actuators, Gold, Electrodes, Polymers, Metals, Capacitance, Transducers, Single walled carbon nanotubes, Liquids, Carbon nanotubes

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Ionic electroactive actuators have received considerable attention in the past ten years. Ionic electroactive polymers, sometimes referred to as artificial muscles, have the ability to generate large bending strain and moderate stress at low applied voltages. Typical types of ionic electroactive polymer transducers include ionic polymers, conducting polymers, and carbon nanotubes. Preliminary research combining multiple types of materials proved to enhance certain transduction properties such as speed of response, maximum strain, or quasi-static actuation. Recently it was demonstrated that ionomer-ionic liquid transducers can operate in air for long periods of time (>250,000 cycles) and showed potential to reduce or eliminate the back-relaxation issue associated with ionomeric polymers. In addition, ionic liquids have higher electrical stability window than those operated with water as the solvent thereby increasing the maximum strain that the actuator can produce. In this work, a new technique developed for plating metal particulates on the surface of ionomeric materials is applied to the development of hybrid transducers that incorporate carbon nanotubes and conducting polymers as electrode materials. The new plating technique, named the direct assembly process, consists of mixing a conducting powder with an ionomer solution. This technique has demonstrated improved response time and strain output as compared to previous methods. Furthermore, the direct assembly process is less costly to implement than traditional impregnation-reduction methods due to less dependence on reducing agents, it requires less time, and is easier to implement than other processes. Electrodes applied using this new technique of mixing RuO₂ (surface area 45~65m²/g) particles and Nafion dispersion provided 5x the displacement and 10x the force compared to a transducer made with conventional methods. Furthermore, the study illustrated that the response speed of the transducer is optimized by varying the vol% of metal in the electrode. For RuO₂, the optimal loading was approximately 45%. This study shows that carbon nanotubes electrodes have an optimal performance at loadings around 30 vol%, while PANI electrodes are optimized at 95 vol%. Due to low percolation threshold, carbon nanotubes actuators perform better at lower loading than other conducting powders. The addition of nanotubes to the electrode tends to increase both the strain rate and the maximum strain of the hybrid actuator. SWNT/RuO₂ hybrid transducer has a strain rate of 2.5%/sec, and a maximum attainable peak-to-peak strain of 9.38% (+/- 2V). SWNT/PANI hybrid also increased both strain and strain rate but not as significant as with RuO₂. PANI/RuO₂ actuator had an overwhelming back relaxation.

Proceedings Article | 27 July 2004 Paper

Developing a polymeric sensor to monitor intracellular conditions

Timothy Mudarri, Donald Leo, Brett Wood, Peter Shires

Proc. SPIE. 5385, Smart Structures and Materials 2004: Electroactive Polymer Actuators and Devices (EAPAD)

KEYWORDS: Sensors, Polymers, Ions, Calcium, Bone, Capacitance, Sodium, Cesium, Ion exchange, Polymeric sensors

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Proceedings Article | 27 July 2004 Paper

Effects of electrode morphology on the performance of BPSH and PATS ionic polymer transducers

Barbar Akle, Kenton Wiles, Donald Leo, James McGrath

Proc. SPIE. 5385, Smart Structures and Materials 2004: Electroactive Polymer Actuators and Devices (EAPAD)

KEYWORDS: Actuators, Electrodes, Polymers, Metals, Platinum, Scanning electron microscopy, Capacitance, Transducers, Acquisition tracking and pointing, Plating

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Proceedings Article | 27 July 2004 Paper

Ionic liquids as novel solvents for ionic polymer transducers

Matthew Bennett, Donald Leo

Proc. SPIE. 5385, Smart Structures and Materials 2004: Electroactive Polymer Actuators and Devices (EAPAD)

KEYWORDS: Actuators, Lithium, Electrodes, Polymers, Ions, Platinum, Capacitance, Transducers, Liquids, Polymeric actuators

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Proceedings Article | 26 July 2004 Paper

Electroactive smart polymers for space optics

Arthur Gavrin, Kent Blizard, Donald Leo, Mathew Bennett

Proc. SPIE. 5390, Smart Structures and Materials 2004: Smart Structures and Integrated Systems

KEYWORDS: Actuators, Thin films, Mirrors, Electrodes, Polymers, Control systems, Transducers, Astronomical imaging, Polymer thin films, Liquids

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Proceedings Article | 26 July 2004 Paper

Applying a computational micromechanics model to the hypothesis of polarization response in ionic polymers

Lisa Mauck Weiland, Donald Leo

Proc. SPIE. 5383, Smart Structures and Materials 2004: Modeling, Signal Processing, and Control

KEYWORDS: Optical spheres, Polarization, Electrodes, Polymers, Ions, Resistance, Distortion, 3D modeling, Spherical lenses, Tolerancing

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Proceedings Article | 26 July 2004 Paper

Nonlinear identification of ionic polymer actuator systems

Curt Kothera, Seth Lacy, R. Scott Erwin, Donald Leo

Proc. SPIE. 5383, Smart Structures and Materials 2004: Modeling, Signal Processing, and Control

KEYWORDS: Actuators, Data modeling, Polymers, Complex systems, Distortion, Solids, Analytical research, Intelligence systems, Systems modeling, Polymeric actuators

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Proceedings Article | 21 July 2004 Paper

Temperature influences on the wave propagation technique for use in supplementing impedance-based structural health monitoring

Benjamin Grisso, Donald Leo, Daniel Inman

Proc. SPIE. 5394, Health Monitoring and Smart Nondestructive Evaluation of Structural and Biological Systems III

KEYWORDS: Actuators, Ferroelectric materials, Sensors, Nondestructive evaluation, Wave propagation, Structural health monitoring, Damage detection, Aluminum, Intelligence systems, Temperature metrology

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Proceedings Article | 21 July 2004 Paper

Effects of counter-ion, solvent type, and loading condition on the material response of ionic polymer transducers

Kevin Farinholt, Donald Leo

Proc. SPIE. 5387, Smart Structures and Materials 2004: Active Materials: Behavior and Mechanics

KEYWORDS: Lithium, Electrodes, Polymers, Dielectrics, Calcium, Transducers, Sodium, Motion models, Cesium, Electromechanical design

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Proceedings Article | 30 January 2004 Paper

Novel photomechanical actuators

Joseph Ritter, James Brozik, Luke Emmert, Mike Fallbach, Rodney Bradford, Donald Leo, Ken Meissner

Proc. SPIE. 5166, UV/Optical/IR Space Telescopes: Innovative Technologies and Concepts

KEYWORDS: Actuators, Optical components, Mirrors, Radio optics, Polymers, Wavefronts, Imaging spectroscopy, Control systems, Space telescopes, Active optics

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Proceedings Article | 13 August 2003 Paper

Electromechanical modeling of charge sensing in ionic polymers

Kevin Farinholt, Donald Leo

Proc. SPIE. 5053, Smart Structures and Materials 2003: Active Materials: Behavior and Mechanics

KEYWORDS: Actuators, Lithium, Data modeling, Mechanics, Electrodes, Polymers, Ions, Transducers, Motion models, Systems modeling

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Proceedings Article | 5 August 2003 Paper

Feedback-controlled oscillatory motor using ionic polymer materials

Kenneth Newbury, Donald Leo

Proc. SPIE. 5056, Smart Structures and Materials 2003: Smart Structures and Integrated Systems

KEYWORDS: Actuators, Sensors, Polymers, Amplifiers, Control systems, Transducers, Motion models, Feedback control, Polymeric sensors, Polymeric actuators

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Proceedings Article | 31 July 2003 Paper

Power regeneration in active vibration isolation systems

Nikola Vujic, Donald Leo, Douglas Lindner

Proc. SPIE. 5052, Smart Structures and Materials 2003: Damping and Isolation

KEYWORDS: Actuators, Amplifiers, Control systems, Electroluminescence, Velocity measurements, Resistors, Vibration isolation, Feedback control, Electromagnetism, Systems modeling

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Proceedings Article | 28 July 2003 Paper

Linear constitutive model of ionic polymer bender transducers

Kenneth Newbury, Donald Leo

Proc. SPIE. 5051, Smart Structures and Materials 2003: Electroactive Polymer Actuators and Devices (EAPAD)

KEYWORDS: Actuators, Sensors, Electrodes, Polymers, Resistance, Transducers, Motion models, Circuit switching, Polymeric sensors, Polymeric actuators

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Proceedings Article | 28 July 2003 Paper

Multilayer ionic polymer transducer

Barbar Akle, Donald Leo

Proc. SPIE. 5051, Smart Structures and Materials 2003: Electroactive Polymer Actuators and Devices (EAPAD)

KEYWORDS: Mathematical modeling, Packaging, Actuators, Multilayers, Sensors, Polymers, Resistance, Transducers, Polymeric sensors, Polymeric actuators

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Proceedings Article | 22 July 2003 Paper

Use of piezoelectric energy harvesting devices for charging batteries

Henry Sodano, Gyuhae Park, Donald Leo, Daniel Inman

Proc. SPIE. 5050, Smart Structures and Materials 2003: Smart Sensor Technology and Measurement Systems

KEYWORDS: Microelectromechanical systems, Ferroelectric materials, Patents, Sensors, Composites, Nickel, Energy harvesting, Transducers, Aluminum, Microsoft Foundation Class Library

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Proceedings Article | 15 July 2002 Paper

Performance of a piezohydraulic actuation system with active valves

Honghui Tan, William Hurst, Donald Leo

Proc. SPIE. 4701, Smart Structures and Materials 2002: Smart Structures and Integrated Systems

KEYWORDS: Actuators, Energy efficiency, Data modeling, Sensors, Ceramics, Control systems, Velocity measurements, Motion models, Systems modeling, Mechanical efficiency

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Proceedings Article | 11 July 2002 Paper

Performance evaluation of bending actuators made from electrostrictive graft elastomers

Ji Su, Robert Costen, Joycelyn Harrison, Kenneth Newbury, Donald Leo

Proc. SPIE. 4695, Smart Structures and Materials 2002: Electroactive Polymer Actuators and Devices (EAPAD)

KEYWORDS: Microelectromechanical systems, Actuators, Gold, Data modeling, Electrodes, Polymers, Performance modeling, Systems modeling, Prototyping, Electroactive polymers

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Proceedings Article | 11 July 2002 Paper

Extensional transduction properties of ionic polymer materials

Orion Parrott, Alyssa Nicolaisen, Donald Leo

Proc. SPIE. 4695, Smart Structures and Materials 2002: Electroactive Polymer Actuators and Devices (EAPAD)

KEYWORDS: Actuators, Data modeling, Electrodes, Polymers, Transducers, Signal processing, Intelligence systems, Ferroelectric polymers, Electroactive polymers, Polymeric actuators

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Proceedings Article | 11 July 2002 Paper

Electrically induced permanent strain in ionic polymer-metal composite actuators

Kenneth Newbury, Donald Leo

Proc. SPIE. 4695, Smart Structures and Materials 2002: Electroactive Polymer Actuators and Devices (EAPAD)

KEYWORDS: Actuators, Digital signal processing, Cameras, Electrodes, Polymers, Composites, Amplifiers, Picosecond phenomena, Intelligence systems, Polymeric actuators

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Proceedings Article | 27 June 2002 Paper

Power flow analysis for amplifier design and energy harvesting

Nikola Vujic, Donald Leo, Douglas Lindner

Proc. SPIE. 4697, Smart Structures and Materials 2002: Damping and Isolation

KEYWORDS: Actuators, Computing systems, Fourier transforms, Amplifiers, Control systems, Energy harvesting, Vibration isolation, Feedback control, Electromechanical design, Absorption

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Proceedings Article | 16 August 2001 Paper

Modeling and testing of a piezohydraulic actuation system

Khalil Nasser, Nikola Vujic, Donald Leo, Harley Cudney

Proc. SPIE. 4327, Smart Structures and Materials 2001: Smart Structures and Integrated Systems

KEYWORDS: Actuators, Smart structures, Motion models, System integration, Systems modeling, Smart materials

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Proceedings Article | 6 August 2001 Paper

Sensing capabilities of ionic polymer-metal composites

Mohsen Shahinpoor, Kwang Kim, Benjamin Henderson, Donald Leo

Proc. SPIE. 4328, Smart Structures and Materials 2001: Sensory Phenomena and Measurement Instrumentation for Smart Structures and Materials

KEYWORDS: Sensors, Electrodes, Polymers, Particles, Composites, Ions, Diffusion, Resistance, Platinum, Scanning electron microscopy

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Proceedings Article | 16 July 2001 Paper

Feedback control of the bending response of ionic polymer-metal composite actuators

Kiran Mallavarapu, Kenneth Newbury, Donald Leo

Proc. SPIE. 4329, Smart Structures and Materials 2001: Electroactive Polymer Actuators and Devices

KEYWORDS: Actuators, Polymers, Composites, Robotics, Motion models, Feedback control, Control systems design, Systems modeling, Device simulation, Polymeric actuators

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Proceedings Article | 2 July 2001 Paper

Piezoelectric isolation system for lightweight automotive seats

Mark Malowicki, Donald Leo

Proc. SPIE. 4331, Smart Structures and Materials 2001: Damping and Isolation

KEYWORDS: Actuators, Digital signal processing, Roads, Foam, Interference (communication), Control systems, Vibration isolation, Feedback control, Californium, Active isolation

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Proceedings Article | 14 June 2001 Paper

Comparison of drive amplifier for piezoelectric actuators

Douglas Lindner, Nikola Vujic, Donald Leo

Proc. SPIE. 4332, Smart Structures and Materials 2001: Industrial and Commercial Applications of Smart Structures Technologies

KEYWORDS: Actuators, Ferroelectric materials, Signal attenuation, Computing systems, Amplifiers, Control systems, Vibration control, Feedback control, Systems modeling, Device simulation

Read Abstract +

Proceedings Article | 22 June 2000 Paper

Airflow control systems for miniature fuel cells

Donald Leo, Khalil Nasser

Proc. SPIE. 3985, Smart Structures and Materials 2000: Smart Structures and Integrated Systems

KEYWORDS: Actuators, Energy efficiency, Electronics, Hydrogen, Amplifiers, Control systems, Oxygen, Mechanical engineering, Electrical efficiency, Mechanical efficiency

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Proceedings Article | 12 June 2000 Paper

Compact piezohydraulic actuation system

Khalil Nasser, Donald Leo, Harley Cudney

Proc. SPIE. 3991, Smart Structures and Materials 2000: Industrial and Commercial Applications of Smart Structures Technologies

KEYWORDS: Actuators, Electronics, Microfluidics, Amplifiers, Control systems, Transducers, Signal processing, Mechanical engineering, Electrical efficiency, Systems modeling

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Proceedings Article | 27 April 2000 Paper

Constrained-substructure approach to optimal strain energy analysis

Donald Leo, Eric Austin, Christopher Beattie

Proc. SPIE. 3989, Smart Structures and Materials 2000: Damping and Isolation

KEYWORDS: Ferroelectric materials, Sensors, Matrices, Aluminum, Structural design, Intelligence systems, Chemical elements, Optimization (mathematics), Mechanical engineering, Passive elements

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Proceedings Article | 9 July 1999 Paper

Active seat isolation for hybrid electric vehicles

Donald Leo, Mark Malowicki, Stephen Buckley, Ganapathy Naganathan

Proc. SPIE. 3674, Smart Structures and Materials 1999: Industrial and Commercial Applications of Smart Structures Technologies

KEYWORDS: Actuators, Optical filters, Roads, Data modeling, Matrices, Control systems, Numerical analysis, Motion models, Smart materials, Active isolation

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Proceedings Article | 4 June 1999 Paper

Matrix method for analyzing structural-acoustic power efficiency

Renfang Cao, Donald Leo

Proc. SPIE. 3667, Smart Structures and Materials 1999: Mathematics and Control in Smart Structures

KEYWORDS: Actuators, Ferroelectric materials, Finite element methods, Shape analysis, Dynamical systems, Chemical elements, Motion models, Acoustics, Motion analysis, Mechanical efficiency

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Proceedings Article | 27 July 1998 Paper

Microcontroller-based implementation of adaptive structural control

Donald Leo, Steven Griffin

Proc. SPIE. 3329, Smart Structures and Materials 1998: Smart Structures and Integrated Systems

KEYWORDS: Actuators, Sensors, Digital filtering, Amplifiers, Signal processing, Microcontrollers, Algorithm development, Adaptive control, Feedback control, Analog filtering

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Proceedings Article | 24 July 1998 Paper

Eigenvalue technique for analyzing structural-acoustic power efficiency

Renfang Cao, Donald Leo

Proc. SPIE. 3323, Smart Structures and Materials 1998: Mathematics and Control in Smart Structures

KEYWORDS: Actuators, Sensors, Error analysis, Fourier transforms, Finite element methods, Shape analysis, Chemical elements, Algorithm development, Acoustics, Mechanical efficiency

Read Abstract +

Proceedings Article | 16 June 1998 Paper

Vehicular applications of smart material systems

Donald Leo, Craig Weddle, Ganapathy Naganathan, Stephen Buckley

Proc. SPIE. 3326, Smart Structures and Materials 1998: Industrial and Commercial Applications of Smart Structures Technologies

KEYWORDS: Actuators, Electronics, Safety, Sensors, Control systems, Telecommunications, System integration, Content addressable memory, Smart materials, Electromechanical design

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Proceedings Article | 6 June 1997 Paper

Reconfigurable actuator-sensor arrays for the active control of sound

Donald Leo, Jonathan How

Proc. SPIE. 3041, Smart Structures and Materials 1997: Smart Structures and Integrated Systems

KEYWORDS: Actuators, Electronics, Digital signal processing, Spatial filters, Sensors, Amplifiers, Signal processing, Feedback control, Digital electronics, Ferroelectric polymers

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Proceedings Article | 6 June 1997 Paper

Comparison of point force and distributed actuators for the active control of structural sound radiation

Donald Leo, Jeffrey Paine

Proc. SPIE. 3041, Smart Structures and Materials 1997: Smart Structures and Integrated Systems

KEYWORDS: Actuators, Manufacturing, Wave plates, Solids, Algorithm development, Adaptive control, Acoustics, Feedback control, Semiconducting wafers, Control systems design

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Proceedings Article | 31 May 1996 Paper

Optimal control design for systems with collocated sensors and actuators

Donald Leo, Daniel Inman

Proc. SPIE. 2715, Smart Structures and Materials 1996: Mathematics and Control in Smart Structures

KEYWORDS: Actuators, Sensors, Matrices, Numerical simulations, Control systems, Feedback control, Control systems design, Smart materials, Darmstadtium, Convex optimization

Read Abstract +

Proceedings Article | 1 May 1996 Paper

Ultraquiet platform for active vibration isolation

Eric Anderson, Donald Leo, Mark Holcomb

Proc. SPIE. 2717, Smart Structures and Materials 1996: Smart Structures and Integrated Systems

KEYWORDS: Actuators, Sensors, Magnetism, Control systems, Space operations, Motion measurement, Vibration isolation, Optical isolators, Electromagnetism, Active isolation

Read Abstract +

Proceedings Article | 5 May 1995 Paper

Active/passive controller synthesis based on H-infinity power flow techniques

Donald Leo, Joseph Slater

Proc. SPIE. 2442, Smart Structures and Materials 1995: Mathematics and Control in Smart Structures

KEYWORDS: Mathematical modeling, Actuators, Data modeling, Sensors, Matrices, Control systems, Transform theory, Motion models, Feedback control, Control systems design

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Proceedings Article | 1 May 1992 Paper

Smart slewing frames

Donald Leo

Proc. SPIE. 1777, First European Conference on Smart Structures and Materials

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Showing 5 of 95 publications

Proceedings Volume Editor (5)

SPIE Conference Volume | 4 May 2017

A Tribute Conference Honoring Daniel Inman

SPIE Conference Volume | 6 May 2008

Active and Passive Smart Structures and Integrated Systems 2008

SPIE Conference Volume | 30 March 2007

Active and Passive Smart Structures and Integrated Systems 2007

SPIE Conference Volume | 16 March 2006

Smart Structures and Materials 2006: Smart Structures and Integrated Systems

SPIE Conference Volume | 17 May 2005

Smart Structures and Materials 2005: Smart Structures and Integrated Systems

Conference Committee Involvement (40)

Behavior and Mechanics of Multifunctional Materials XV

8 March 2021 | Online Only, California, United States

Behavior and Mechanics of Multifunctional Materials XIV

27 April 2020 | Online Only, California, United States

Smart Structures and NDE for Industry 4.0, Smart Cities, and Energy Systems

27 April 2020 | Online Only, California, United States

Smart Structures and NDE for Energy Systems and Industry 4.0

4 March 2019 | Denver, Colorado, United States

Behavior and Mechanics of Multifunctional Materials XIII

4 March 2019 | Denver, Colorado, United States

Smart Structures and NDE for Industry 4.0

5 March 2018 | Denver, Colorado, United States

Behavior and Mechanics of Multifunctional Materials and Composites XII

5 March 2018 | Denver, Colorado, United States

A Tribute Conference Honoring Daniel Inman

29 March 2017 | Portland, Oregon, United States

Industrial and Commercial Applications of Smart Structures Technologies XI

26 March 2017 | Portland, Oregon, United States

Behavior and Mechanics of Multifunctional Materials and Composites XI

26 March 2017 | Portland, Oregon, United States

Industrial and Commercial Applications of Smart Structures Technologies X

21 March 2016 | Las Vegas, Nevada, United States

Behavior and Mechanics of Multifunctional Materials and Composites X

21 March 2016 | Las Vegas, Nevada, United States

Industrial and Commercial Applications of Smart Structures Technologies IX

9 March 2015 | San Diego, California, United States

Behavior and Mechanics of Multifunctional Materials and Composites IX

9 March 2015 | San Diego, California, United States

Behavior and Mechanics of Multifunctional Materials and Composites VIII

10 March 2014 | San Diego, California, United States

Behavior and Mechanics of Multifunctional Materials and Composites VII

10 March 2013 | San Diego, California, United States

Behavior and Mechanics of Multifunctional Materials and Composites VI

12 March 2012 | San Diego, California, United States

Behavior and Mechanics of Multifunctional Materials and Composites V

7 March 2011 | San Diego, California, United States

SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring

6 March 2011 | San Diego, United States

Behavior and Mechanics of Multifunctional Materials and Composites IV

8 March 2010 | San Diego, California, United States

SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring

7 March 2010 | San Diego, United States

Second International Conference on Smart Materials and Nanotechnology in Engineering

8 July 2009 | Weihai, China

Behavior and Mechanics of Multifunctional Materials and Composites III

9 March 2009 | San Diego, California, United States

SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring

8 March 2009 | San Diego, United States

Behavior and Mechanics of Multifunctional and Composite Materials II

10 March 2008 | San Diego, California, United States

Active and Passive Smart Structures and Integrated Systems II

10 March 2008 | San Diego, California, United States

SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring

9 March 2008 | San Diego, United States

Behavior and Mechanics of Multifunctional and Composite Materials

19 March 2007 | San Diego, California, United States

Active and Passive Smart Structures and Integrated Systems

19 March 2007 | San Diego, California, United States

Damping and Isolation

27 February 2006 | San Diego, California, United States

Smart Structures and Integrated Systems

27 February 2006 | San Diego, California, United States

Active Materials: Behavior and Mechanics

27 February 2006 | San Diego, California, United States

Damping and Isolation

7 March 2005 | San Diego, California, United States

Smart Structures and Integrated Systems

7 March 2005 | San Diego, California, United States

Active Materials: Behavior and Mechanics

7 March 2005 | San Diego, California, United States

Electroactive Polymer Actuators and Devices (EAPAD)

7 March 2005 | San Diego, California, United States

Damping and Isolation

15 March 2004 | San Diego, CA, United States

Active Materials: Behavior and Mechanics

15 March 2004 | San Diego, CA, United States

Damping and Isolation

3 March 2003 | San Diego, California, United States

Active Materials: Behavior and Mechanics

3 March 2003 | San Diego, California, United States

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