We have prepared polypyrrole (PPy) / MoO3 nanohybrid thin films and evaluated their volatile organic compound (VOC) gas sensing properties. The (PPy)xMoO3 thin films have been prepared by intercalation reactions of highly oriented MoO3 thin films. Intercalation of hydrated sodium ions successfully proceeded without loosing the crystallographic orientation. The (PPy)xMoO3 thin films was obtained by replacing the hydrated sodium ions with PPy. The (PPy)xMoO3 thin films can detect formaldehyde gas by increasing in their electrical resistance, whereas they showed no response to toluene.

This letter reports a Pb(Zr0.5Ti0.5)O3 (PZT) based composition, which provides high dielectric, piezoelectric and electromechanical properties. The composition corresponding to 0.2 PZN – 0.8 PZT + 0.5 wt% MnO2 provides the radial mode coupling factor (kp) of 0.58, longitudinal mode piezoelectric constant (d33) of 277 pC/N, dielectric constant (ε33/εo) of 946 and mechanical quality factor (Qm) of 1402. X-ray diffraction, dielectric and polarization-electric field measurements were done to investigate the origin for this high performance. It was found that high soft properties are obtained due to the shifting of PZT composition towards morphotropic phase boundary (MPB) and high hard properties are obtained due to the generation of dipolar defects which pin the polarization. The properties of the composition corresponding to 0.9 PZT – 0.1PMnN (Zr/Ti = 0.51/0.49) modified with 6 mol% Sr were found to be: kp = 0.53, Qm = 800, d33 = 274, ε33/εo = 1290 and tanδ = 1.1 %, with a TCF of -8 ppm/oC (-20 to 80°C). High piezoelectric properties with low TCF shows the suitability of this composition for ultrasonic devices used under fluctuating thermal environment.

Hydrogen-free carbon nanotube composites have been created that possess unusual free radical generation properties. These films have the ability to nonspecifically kill bacterial cells and can be used to sterilize a surface. These composites have been formed by simultaneous pulsed laser ablation of carbon and bombardment of nitrogen ions generated by a Kaufman ion source at high temperatures (600- 700°C). The results suggest the creation of a new form of carbon that is predominantly trigonally-coordinated, with small fractions of carbon-nitrogen bonds. TEM studies allow us to conclude that the material consists of sp2-bonded ribbons wrapped approximately +/-15° normal to the surface. Plan-view high resolution TEM specimens demonstrate layers with curvature similar to that seen in multiwalled nanotube structures. In addition, the interlayer order extends to approximately 15–30 nm. These novel structures result from the use of energetic ions, which create nonequilibrium conditions that alter the growth mode of graphitic planes. In vitro testing revealed significant antimicrobial activity against Staphylococcus aureus bacteria. Possible applications include use on the functional surfaces of dialysis equipment, scalpels, and other sterile equipment.

In a magneto-surface-acoustic-wave (MSAW) device, phase velocity is controlled by an external magnetic field. We proposed amplification of MSAW with a hybrid structure of FeB amorphous film / InSb semiconductor thin film / LiNbO3 substrate, which is expected to compensate the attenuation of MSAW caused by eddy current loss. In the fabricated MSAW device having the FeB amorphous film with low coercivity and high magnetostrictive, the phase retardation of about 600 degree/cm at magnetic fields of ±300 Oe was obtained. The InSb thin film with a mobility of about 3.5×103 cm2/Vs was obtained by using annealing process. The results show possibility of the MSAW amplification.

We report the fabrication and characterization of a novel composite material based on single walled carbon nanotubes (SWNT)s and the ionomeric polymer Nafion. SWNTs were airbrushed from a chloroform suspension onto both sides of a Nafion membrane (180 μm) and the electromechanical properties of the composite material were explored. The outer layers of carbon nanotubes acted as electrodes in order to pass electrical current through the system while the mechanical response was monitored. Under this design, the mechanical response could be characterized, with respect to the electrical signal, as a function of: voltage, waveform (AC vs. DC), and frequency (AC). Data was also compiled to gauge the effect of size and thickness of each individual layer of the system. The reference samples (graphite-Nafion and sputtered gold-Nafion) did not exhibit mechanical actuation at the same conditions. An analytical model for current decay was considered that is in agreement with the experimental data. Bi-exponential decay with a long time component was found for bias, which is above the actuating threshold. That was explained in terms of increasing of the water dielectric constant and polymer-SWNT interface area. The possible mechanisms of the actuation in this novel composite are discussed.

Metal-carbon nanocomposites are characterized by a number of unique properties, perspective for the various-type applications. The presented experimental data on the conductivity of amorphous tungsten- and niobium-containing carbon-silicon nanocomposite films show the possibility of the design of advanced wide-range temperature sensors, which are expected to possess the chemical stability, biocompatibility, mechanical, and other properties typical for this class of materials. The films were deposited onto polycrystalline substrates using combination of PECVD(Plasma Enhanced Chemical Vapor Deposition) of siloxane vapors and magnetron co-sputtering of metal target. The conductivity σ of the films, measured using standard 4-probe technique in the temperature range 80–400K, is characterized by the gradual decrease with temperature. The experimental σ(T) dependences are well fitted by the universal power expression, σ(T)= σ0+aTn, where σ0, a, and n are the fitting parameters dependent on the value of metal concentration. The conductivity mechanisms in the investigated amorphous metal-containing carbon-silicon nanocomposite films are discussed in the framework of the model of inelastic tunneling in amorphous insulators in the presence of the structural transformation in carbon-silicon matrix.

A ceramic strain gage based on reactively sputtered indium tin oxide thin films is being developed to monitor the structural integrity of components employed in aerospace propulsion systems that operate at temperatures in excess of 1500°C. When relatively thick indium-tin-oxide (ITO) strain gages were prepared by reactive sputtering in oxygen:argon atmospheres and annealed in nitrogen, an extremely stable piezoresistive response was observed at temperatures as high as 1530°C. SEM and AFM of these sensor surfaces after high temperature exposure revealed a partially sintered microstructure with interconnected nanoporosity. Specifically, the microstructure consisted of a contiguous network of uniform sized ITO particles with well-defined necks between individual particles. When these microstructures were compared to those of relatively thin ITO sensors sputtered in nitrogen:argon:oxygen atmospheres, i.e. ITO films prepared in a nitrogen rich plasma, the average pore size and particle size was estimated to be an order of magnitude smaller than those associate with thick ITO sensors. In the nitrogen sputtered films, enhanced electrical conduction along the surfaces of the contiguous ITO particles resulted in a very stable and large piezoresistive response with a gage factor of 11.4 and a drift rate of 0.0001%/hour at 1560°C. The improved performance realized when the ITO films were processed in nitrogen may be extended to other ITO based sensors including gas sensors and the advantages of films processed in this manner will be discussed.

Freestanding Ni50Mn30Ga20 films of 13 μm thickness were fabricated by DC magnetron sputtering and analyzed. Magnetic measurements revealed the influence of the post deposition rapid thermal annealing process on the ferromagnetic hysteresis. Ferromagnetic properties evolved after annealing at 400°C. Thermal annealing of at least 600°C led to polycrystalline films that transformed reversibly and martensitically as shown by structural analysis and differential scanning calorimetry. Transformation temperatures and enthalpies of transformation of the martensitic transformation were strongly influenced by the temperature of the rapid annealing process. It is proposed that the annealing data reflect the evolution of the crystalline state.

Single-walled carbon nanotubes (SWNTs) have attracted much attention due to their unique structural, mechanical, chemical, and electrical properties. Catalytic chemical vapor deposition (CCVD) through decomposition of hydrocarbons is one of the most challenging synthesis methods to produce SWNTs in large scale. In this paper, high quality SWNTs prepared in a nano-agglomerated fluidized bed reactor (NAFBR) was reported. The reactor is a vertical quartz tube with the inner diameter of about 50 mm. Catalysts nanoparticles used for the production of SWNTs were prepared with Fe metal nanoparticles carried on the surface of MgO. About 150g catalysts powders were loaded on the gas distribution grid. The reaction temperature was controlled at not less than 1123 K. The carrier gas of argon was used to maintain turbulent fluidization of the catalysts powders in FBR. The hydrogen gas was used to reduce the catalysts and to synergize the growth of SWNTs with methane. The powder products were spherical agglomerates of SWNTs bundles tangling with the catalysts particles. By optimizing the process parameters of CCVD, the products of SWNTs with the diameter about 0.9 ∼ 1.8 nm were prepared, without any multi-walled carbon nanotubes (MWNTs) or amorphous carbon. The microstructure of SWNTs products were characterized by the methods of high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), Raman spectra, etc. The NAFBR is a commercially viable (effective and continuous production at a low cost) process for the production of SWNTs.

This research is focused on the design and experimental characterization of an electrothermal microengine that is capable of bi-directional motion. The microengine has been operated to control the position a linear shuttle and rotate a set of gears.

In this paper we present the accelerated reliability testing of MgZnO based UV detectors. The UV detectors are fabricated on glass, quartz and sapphire substrates by Pulsed Laser Deposition (PLD) technique. The films are highly oriented and show sharp transmission at 350nm and 330nm for Mg composition of 10% and 20% in ZnO, respectively. The device response has been studied and life expectancy of the devices has been estimated from the accelerated tests.

BioMEMs and microfluidic devices have gained a lot of attention in recent years due to their emerging applications in biochemical analysis, medical diagnosis, chemical analysis and synthesis, drug discovery and drug delivery, biosensing and biomimetic systems. The materials requirements for bioMEMs are biocompatible, chemically modifiable, easy to fabricate, economic, compliable and smart. Among various materials, the electroactive polymeric materials can best meet these requirements. Recently, we developed a group of poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE) based terpolymers which have very high strain level and high energy density. The longitudinal and transverse strain of these materials can reach about –7% and 4.5%, and the elastic energy density is around 1.1 J/cm3, which are very attractive for the development of polymeric pump, valve and other microfluidic components for all polymer-based bioMEMs and microfluidic integrated system. This paper reports on the recent efforts on the optimization of the terpolymer performance and development of microfluidic components using the electroactive terpolymers for bioMEMs.

Advancements in microelectromechanical technologies have lead to progressive design of small footprint, low dynamic mass and actuation power, and high-resolution MEMS inertial sensors. In this paper, development of instrumentation and methodologies for wireless health monitoring of structures using MEMS inertial sensors is presented. A dedicated experimental setup is developed to characterize specific MEMS inertial sensors and structures. Studies presented in this paper include development and characterization of a prototype wireless data acquisition system to transmit analog and digital signals. Results show that the frequency response of the prototype wireless data acquisition system is compatible with the frequency response of the MEMS inertial sensors utilized. The prototype wireless MEMS inertial system is applied to perform tilt and rotation measurements. It is shown that with the wireless MEMS system it is possible to achieve an angular resolution of 1.8 mrad.

The characteristics of dopant activation by sequential lateral solidification in poly-Si films is investigated using sheet resistance measurement and Raman measurement. Sheet resistance of n+ and p+ doped poly-Si films decreases exponentially as the laser energy increases. The minimum sheet resistance of n+ doped poly-Si films is 150 Ω/□ which is near to that of rapid thermal annealing (RTA) while the minimum sheet resistance of p+ doped poly-Si films is 180 Ω/□ which is less than a half to that of RTA. The sheet resistance of n+ and p+ doped poly-Si increases as the laser energy increases when the laser energy is above 573 mJ/cm2 at which the nucleation occurs. Raman signal of n+ doped poly-Si films shows single peak at 515 cm-1 with all laser energy and has maximum intensity at 566 mJ/cm2 laser energy. Raman signal of p+ doped poly-Si films shows single peak below 413 mJ/cm2 laser energy and double peak above 444 mJ/cm2 laser energy where the fully melting of p+ doped poly-Si film occurs.

The relative permittivity of (x)Pb(In1/2Nb1/2)O3:(1-x)Pb(Mg1/3Nb2/3)O3 ceramics with compositions x=0.1, 0.3 and 0.6 were found to exhibit relaxor behavior. The maximum values of the relative permittivity at 100 Hz were ∼ 6500 at -2°C, 4000 at 5°C and 3700 at 15°C for x=0.1, 0.3 and 0.6, respectively. The 1:1 structural long-range ordering and forbidden reflections were studied by transmission electron microscopy. The size of the ordered domains increased with increasing Pb(In1/2Nb1/2)O3. In addition to the superstructure reflection 1/2 1/2 1/2, the forbidden reflection 1/2 1/2 0 and streaking were observed.

This paper describes new concepts the author has proposed and demonstrated to realize metal and polymer based sensitive and/or active structural material systems suitable for smart structures. Most of the developments have been done by simple and innovative methods without using sophisticated and expensive sensors and actuators. The following topics are mainly examined: (1) forming optical interference and loss type strain sensors in epoxy matrix simply by embedding and breaking notched optical fiber in it; (2) forming a multifunctional sensor in aluminum matrix for temperature and strain monitorings by embedding an oxidized nickel fiber; (3) fabricating multifunctional composites by using conventional structural materials -an active laminate of CFRP/aluminum of which unidirectional actuation is realized by electrical resistance heating of carbon fiber in the CFRP layer and its curvature change can be monitored using optical fiber multiply fractured in the CFRP layer; (4) fabricating active fiber-reinforced metals such as SiC/Al and SiC/Ni systems by laminating a reinforced layer with a unreinforced layer to cause thermal deformation. In the case of SiC/Al composite, actuation was performed only in the fiber direction and is useful for making a light-weight active panel. In the case of SiC/Ni composite, actuation took place up to above 1200K and is useful for making a high temperature actuator.

Embedded structural health monitoring systems are envisioned to be an important component of future transportation systems. One of the key challenges in designing an SHM system is the choice of sensors, and a sensor layout, which can detect unambiguously relevant structural damage. This paper focuses on the relationship between sensors, the materials of which they are made, and their ability to detect structural damage. Sensor selection maps have been produced which plot the capabilities of the full range of available sensor types vs. the key performance metrics (power consumption, resolution, range, sensor size, coverage). This exercise resulted in the identification of piezoceramic Lamb wave transducers as the sensor of choice. Experimental results are presented for the detailed selection of piezoceramic materials to be used as Lamb wave transducers.

The internal stress distribution in multilayer actuator was analyzed by a numerical simulation. Around the edge of conventional inter-digital electrodes, the non-uniform electric field generated the stress concentration, which caused the ceramic to crack. Various electrode configurations were presented to decrease this stress concentration. Especially the float electrode type is a promising design because this can be fabricated using almost the same process as the conventional multilayer actuator, and the simulated results indicted that the float electrode type decreased the stress concentration of inter-digital type in approximately 1/3.

An high performance / inexpensive diskbender actuator was produced by combining efficient design and fabrication methods and a new technique to operate these actuators was developed and tested, which can enhance the displacement and force capabilities by almost a factor of 2 by using the same maximal driving voltage.

The properties of these actuators are intermediate between those of standard bimorphs, used for very large displacements but providing rather small forces, and those of low voltage stack multilayers, which provide quite large forces but are generally heavier, larger and expensive for equivalent displacements. The absence of any external mechanical amplification mechanism and their geometry make these actuators particularly suitable for active vibration damping applications within buildings affected by perturbations of hundreds of μm or for noise control by emission of controlled sound in antiphase. The class of displacement/force, which can be obtained with suitably dimensioned actuators, provides sufficient high motion even for the lower audio frequency region (400–1500 Hz).

In order to lower the driving voltages, multilayer diskbenders were also fabricated with the same technique. The number of layers does not influence the actuator displacement and force properties but the increased capacity of the actuator may require sophisticated driving amplifiers.

ZnO, a well-known piezoelectric material, is used to develop micro-scale Surface Acoustic Wave (SAW) delay line sensor. In this work, SAW delay line Devices are fabricated employing ZnO films that are deposited by RF sputtering technique. Films are characterized prior to device fabrication by X-Ray Diffraction (XRD) for film crystalline quality, UV-visible transmission spectroscopy for optical characteristics, and Atomic Force Microscopy (AFM) for surface morphology. Interdigital electrodes producing surface acoustic waves in the hundreds of MHz are developed by photolithography and metalization techniques. SAW delay line device testing, measurement and characteristics on RF sputtered ZnO films are presented and compared.