Helical structures have been fabricated from a solution of poly(2-acrylamido-2-methyl-1-propane sulfonic acid) (PAMPS) in water and ethanol by the whipping instability of a jet in a conventional electrospinning system. The simple modification of the electrospinning system involved introducing two parallel subelectrodes, which enabled the transformation of helical nanofibers into linearly oriented nanofibers due to the tensional forces caused by the modified electric field. This means that the tensional forces caused by the modified electric field had an important effect on linearizing the helical structures. Therefore, a technique using modified electric fields can play a significant role as an intermediary between helical structures and one-dimensional linear structures.

Gadolinium-substituted Bi4Ti3O12 (i.e. Bi4−xGdxTi3O12) were synthesized by sol-gel process for different compositions, and thin films were deposited on Pt (Pt/TiO2/SiO2/Si) substrate by spin coating. Post annealed films at 700° C were investigated for their structural properties using x-ray diffraction and Raman spectroscopy indicating solid solution for compositions: x = 0.00, 0.46, 0.56, and 0.85 where Bi ion is replaced by Gd-ion. Sol-gel derived Pt/Bi4−xGdxTi3O12 film/Pt capacitor structure was tested for dielectric, ferroelectric, and leakage current responses. Films showed ferroelectricity with polarization, Pr = 22 µC/cm2 for composition: x = 0.46. Magnetic response of the powder sample for composition: x = 0.85 was tested using SQUID, which showed superparamagnetic at room temperature and magnetic at 5 K with magnetic coercivity (Hc) = 29 Oe and very small remanance (σr) = 5.4 × 10−4 emu/g.

The effects of hot carriers on the transfer characteristics of self-aligned and offset-gated polysilicon thin-film transistors (TFTs), with channel length L = 10 μm and offset length ΔL = 2 μm, are investigated. In the self-aligned device, the on-state current is substantially reduced, whereas the subthreshold slope remains almost unaffected. In the offset gated device, the transfer characteristic is shifted first positively and then negatively, the on-state current is still substantially reduced and well-defined kinks are formed in the subthreshold region. The device degradation is found to become more pronounced in the offset gated device. A model explaining the post-stress performance of the offset-gated device is presented.

Insulator-to-metal phase transition (PT) and relaxation dynamics in VO2 were studied with ultrafast transient reflection spectroscopy and degenerate four wave mixing technique. Optical pumping of free carriers in VO2 initiates PT on a femtosecond time scale. The relaxation dynamics is strongly dependent on pump energy. Spectral reflectivity behaviour at PT due to thermal heating and upon laser excitation of VO2 demonstrates close proximity in the relative change. PT induced by light was interpreted by exciton-controlled mechanism. Excited state dynamics of metallic VO2 is assigned to formations of electronic and hole polaronic states.

The ability of a poly(phenylene ethynylene) conjugated polyelectrolyte to detect a small molecule quencher in the solid state was assessed by coating the polymer onto a plastic-backed, non-fluorescent, silica-gel TLC plate. The efficiency of the emission quenching process was quantified by noting the resulting loss of emission with increasing quencher concentration, in accordance with the Stern-Volmer relation. The emission quenching induced by the addition of the analyte occurred with Stern-Volmer constants in the range of 103 M−1.

A new passive and remote SAW sensor system having ID tag function is presented. Surface acoustic wave (SAW) devices have been widely used as a chemical and physical sensor for measuring the environment. SAW devices have been also used as identification tags (ID tags). The majority of the work reported on SAW sensors to date has used Rayleigh mode SAW and are concerning a delay line. The other hand, it has been shown that the sensors utilizing the shear horizontal mode SAW (SH-SAW) can be designed to sense the liquid properties. The SH-SAW has the unique characteristic of complete reflection at a 90 degree edge normal to the direction of the propagation. This characteristic makes it possible to construct a reflective delay line using the edge reflection. The reflective delay line can be used for as passive and remote sensing.

In this paper, a passive and remote SAW sensor with a function of identification tags has been designed by using the reflective SH-SAW delay line. The reflective delay line was constructed on the 36 YX LiTaO3 substrate having a 90 degree edge normal to the direction of the SAW propagation. Passive and remote SAW sensor consists of several reflective delay lines having different propagation length. The passive sensor and ID tags were made by the multi-channel delay line. The responses of the sensor and ID tags using the edge reflection of SH-SAW are obtained in time domain. Several experiments were performed to verify the performances of the multi-channel edge reflection sensor. The basic characteristics of the reflective SAW sensor were obtained by measuring the amplitude and phase of reflected wave. The obtained results showed that the reflective SH-SAW sensor was very effective for sensing the physical and chemical properties.

Wireless systems are also suggested for the effective operation of the passive SAW sensor. A novel and simple electronic circuit system for accurately measuring the phase characteristics of responses form multi-channel is proposed. In the application, the reflective delay line has been mounted on cantilever to monitor the strain experimentally. The variation of the SH-SAW velocity on the delay line caused by a strain was measured as the passive SAW sensor response. The velocity varied in proportion to the strain applied to the propagation surface. The results showed that the passive sensor was very effective to measure the strain in a wireless mode and it was found that the system is very suitable to health and safety monitoring of building or airplane wing.

Finally it will be shown some applications of the wireless sensor with ID tags on the measurement of the conductivity and viscosity of same liquids.

A novel process to fabricate a thick silica gel film on an aluminum substrate, named the “gap filling method”, has been developed. The process is based on a sol-gel method accompanied by phase separation in a submillimeter thick space defined by two facing substrates. Dielectric thick film integrated on a metal ground plate is successfully formed by using a SiO2 coated aluminum substrate and a cap plate covered with an amorphous carbon thin film, which control the hydrophilicity and the hydrophobicity of the plates, respectively. A thin continuous layer of less than 0.5 μm thick is formed at the interface between the porous film and the cap plate, which gives the film a smooth surface preferable for patterning metal circuits of an antenna. The observed dielectric constants (εr) at 60 GHz measured by the Fabry-Perot resonator method are in the range between 1.4 and 1.6. Methyl groups homogeneously distributed in the siloxane network give a hydrophobic siloxane gel film, thus the obtained films have enough environmental stability. These results show that the gap filling method is applicable to the preparation of the porous thick film that is needed for antenna applications.

Results that demonstrate the selective development of {100}<001> preferred texture in polycrystalline Fe81.3Ga18.7 plus B (0.5∼1.0 at.%) and S (∼0.05 at.%) alloys using a conventional rolling and annealing processes are presented in this work. We found that boron improved ductility by enhancing grain boundary cohesion during rolling and sulfur played an important role in controlling the surface energy and formation of the selective growth of {100} grains during annealing. The as-rolled (Fe81.3Ga18.7)+0.5 at.%B+0.005 at.%S sheet had some {100}<011> and near {111}<011> texture corresponding to α-fiber texture parallel to the rolling direction. The near {100}<001> sheet texture was formed in sheet that was annealed at 1200°C for 2h (198 ppm), while the texture of sheet annealed at 1100°C for 4h (165 ppm) was closer to {110}<001>. The maximum observed magnetostriction of 220 ppm was obtained as a result of a double annealed, first at 1000°C for 6h and then at 1200°C for 1h, with the resultant texture closer to the ideal {100}<001> than the less desirable {100}<011>.

Tunneling spectroscopy was carried out on W doped VO2 single crystal in the temperature region across the phase transition. Double pseudo gap structures were observed across the Fermi level at temperatures below the phase transition. When the temperature was increased across the phase transition, the outer gap structure disappeared and the inner gap structure of about 0.36 eV became sharp. A precursor of phase transition to low temperature phase was observed in the tunneling density of states near the Fermi level, when the temperature approached 0.2 K to the threshold of transition in the electrical resistivity.

Aluminum Nitride (AlN) is a technologically important wide band gap semiconductor and a potential piezo-electric material for Biosensor application [1]. It is a clear candidate for the integration of surface acoustic wave (SAW) devices on chips with silicon-based electronics [2]. AlN may also prove to be useful for the integration of mechanical devices and also in the field of packaging of Bio-MEMS devices because of its superior thermal conductivity 130-140 (W/mK, room temp-100 deg C) and nontoxicity. In the current work an attempt has been made to determine the elastic modulus of AlN coated on Si-microcantilevers, employing the concept of symmetrically laminated beam theory for the first time at the micro level thus avoiding the coupling effects. So far the earlier studies have been done only using simple beam theory. Modal vibration frequencies for microcantilevers without and with the AlN coating were used, along with analytical models and knowledge of the Si modulus, to “back out” the modulus of AlN [3].

In this study, multilayered PbTixZr1-xO3 (PZT) samples (produced at sintering temperatures in the range of 1175 °C to 1325 °C) were electrically fatigued by long-term exposure (∼106 cycles) to electric fields, and the parameters of initial and remnant polarization were estimated. Changes in the crystallographic microstructure as a function of sintering temperature Ts were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD) to gain insight on fatigue mechanisms and their prevention. Results showed that domain wall movement was facilitated in samples processed at TS less than 1250 °C, and that such samples were more resistant to electrical fatigue.

Accurate determination of the resonant frequency, phase and quality factor in micro and nano-mechanical oscillators permits the detection of: (i) trace amounts of specific adsorbed molecules which affect the resonant frequency; (ii) pressure variations which affect the mechanical damping of the oscillator; or (iii) the temperature dependence of the elastic properties of the oscillator through a shift in the resonant frequency. To date, electrical detection of oscillations in cantilevered multiwalled carbon nanotubes (MWNTs) has eluded researchers in the field. Electrical detection allows a simple means for measuring the resonance frequency, phase and quality factor of cantilevers built into integrated circuits, or cantilevers whose response can be monitored as a function of any external parameter such as temperature or pressure. To this end, we described a fully electrical (actuation and detection) method termed harmonic detection of resonance (HDR) to measure mechanical oscillations in ambient conditions for two systems: Si-based micro- and MWNT based nano-cantilevers. Furthermore, we demonstrate that the resonant frequency in micro- and nano-cantilevers can be tuned without appreciable change in the quality factor which suggests that HDR is an ideal platform in device design and applications.

Piezoelectric lead magnesium niobate-lead titanate (PMN-PT) single crystal is one of the most promising materials for electromechanical device applications due to its high electrical field induced strain and high electromechanical coupling factor. PMN-PT single crystal-based multilayer stack actuators and multilayer stack-based flextensional actuators have exhibited high stroke and high displacement-voltage ratios. The actuation capabilities of these two actuators were evaluated using a newly developed method based upon a laser vibrometer system under various loading conditions. The measured displacements as a function of mechanical loads at different driving voltages indicate that the displacement response of the actuators is approximately constant under broad ranges of mechanical load. The load capabilities of these PMN-PT single crystal-based actuators and the advantages of the capability for applications will be discussed.

The purpose of this paper is to report on our work to develop a real-time monitoring device by using micro-cantilevers for the mass detection of biological organisms in air and fluid. The biological agent used was Bacillus anthracis Sterne spore. The experiment was conducted using a laser Doppler vibrometer (LDV) to measure the resonant frequency of the thermal noise cantilevers and the corresponding decrease in frequency as a result of the added mass. Moreover, the added mass attributed to the spores was quantified and compared in air and deionized (DI) water. The silicon cantilevers used in this study were of lengths ranging from 25 μm to 50 μm, 200 nm thick and a width of approximately 9 μm. The first part of the experiment consisted of suspending spores onto the cantilevers in fluid, drying the cantilevers, performing measurements in air and extracting the mass of the added spores. The average mass of a spore in air was 367 fg. The second part of the experiment utilized antibody and bovine serum albumin (BSA) physically adsorbed onto the cantilevers in order to fix the spores on the surface during the measurements in deionized water. The extracted mass of a spore in fluid was measured to be an average of 1.85 pg. This study demonstrated the ability to detect biological samples not only in air but also in a liquid environment.

To flight vehicle designer, the ability to adapt air vehicle aerodynamic shape so as to increase the optimum flight envelope is highly desirable. In this work, by distributing piezoelectric actuators on the top and bottom surfaces of a rectangular wing, the improvement of aerodynamic performance of flight vehicle is studied. The approach of the Fictitious Control Surface (FCS) is evaluated at a group of dynamic pressure and wing stiffness, through examining four aspects including the improvement of rolling power, the increase of lift, the decrease of the induced drag and the decrease of the bending moment at root of wing. Then an experimental model of high-speed wind tunnel is designed in order to validate the results of theoretical analysis. The ground tests and wind tunnel tests demonstrate that the lift and rolling moment can be increased by using the favorable aeroelastic effect. And quantificationally the experimental results agree well with the analytical results.

We produced a new metal-core piezoelectric fiber by means of both hydrothermal and extrusion methods. The insertion of a metal core was significant in view of its strength—greater than that of ceramic materials—and in that electrodes are not required in the fiber's sensor and actuator applications. A new smart board was designed by mounting these piezoelectric fibers on the surface of a CFRP composite, and the sensor and the actuator function were evaluated. We showed that self-sensing was possible using this smart board. And function as a sensor and actuator, this board can control the vibration.

Smart composites based on ferromagnetic hybrid aerogels have been prepared. These novel materials change chemistry in response to light to form nanoparticles that react with compounds that are present in the environment of the aerogels. Thus, high surface area silica/functional polymer hybrid aerogels have been formed via sol-gel synthesis. They also can contain coordinated metal-ion species. They are reacted with Fe-precursors to form air stable ferromagnetic aerogels, which they are transformed into active particles themselves or by incorporation of additional metal ions. These active materials, which adhere to tissue, can be positioned magnetically within their environment. Once they are positioned, they can be transformed by UV light to form Au(0) nanoparticles which react with the molecules in their environment. The preparation and properties of these aerogels, their photochemistry and reaction with bio-molecules will be presented.

In attempts to provide an active solution for the rigidization of flexible space structures, internal resistive heating is applied to a novel thermosetting resin. Carbon-fiber tow coated in U-Nyte Set 201A, which cures at ∼150°C, was heated by passing electric current through the reinforcing material. Using a proportional-integral (PI) controller, precise temperature control of the heating process was established. Samples cured via controlled internal resistive heating were heated to 160°C and underwent material consolidation in less than 7 minutes. A change in material stiffness was measured to be almost two orders of magnitude greater than that of an uncured material.

High performance biosensors are urgently needed from medical diagnosis, to food safety/security, to the war on bio-terrorist. The smart materials play an important role in the development of high performance sensor platform. Biosensors based on microcantilevers have very high sensitivity. The microcantilevers made of different materials, such silicon, piezoelectric and magnetostrictive materials, are discussed and compared in this paper. The magnetostrictive-based microcantilevers exhibit the best performance among all microcantilevers. A new sensor platform – magnetostrictive particles (MSPs) – is reported. The advantages of MSPs over microcantilevers are experimentally demonstrated. The MSPs are wireless/remote sensors, which makes it is possible to employ the MSP-based biosensors in different environments/media. The fabrication of MSPs in micro to nano-scale is reported. Compared with the microcantilevers, MSPs exhibit a better mass sensitivity and a higher Q value, which make the MSPs a much higher overall sensitivity.

In this work, the fabrication of waveguide and nitride silicon membrane is presented. The measurement configuration chosen to detect the variation produced in the light properties is an Interferometer configuration of the Mach Zehnder Type (MZI), because of its high sensitivity. One of its arms is positioned on a floating silicon nitride membrane that becomes deformed under small pressures on the range of MPa. According to the parameters of the membrane and the waveguide we obtain a maximum deformation of 176 nm that produces a change of phase of 180° between the two waves, producing therein a null interferometer output for the maximum pressure.

The analyses of theory suggest that this device will be able to sense a pressure value up to 13.376MPa.