Concrete containing short carbon fibers (0.2-0.5 vol.%) was found to be an intrinsically smart concrete that can sense elastic and inelastic deformation, and fracture. The signal provided is the change in electrical resistance, which is reversible for elastic deformation and irreversible for inelastic deformation and fracture. The presence of electrically conducting short fibers is necessary for the concrete to sense elastic or inelastic deformation, but the sensing of fracture does not require fibers. The fibers serve to bridge the cracks and provide a conduction path. The resistance increase is due to conducting fiber pull-out in the elastic regime, conducting fiber breakage in the inelastic regime, and crack propagation at fracture.

A technique for modeling a superconductor contacted piezoelectric microwave resonator is presented. A transmission line method of modeling the superconductor as a two fluid model is shown to agree with the London penetration depth, and is modeled to take into account the superconductor to normal transition. By including both the normal conductor effects along with the superconductor effects, crystal quality can be factored into this model using an analytical approximation. A two dimensional model for the superconductor, applying experimental results from Y1Ba2Cu3O7−x for circuit elements, is analyzed. The superconducting layer is modeled as an electrical circuit in combination with an acoustical circuit to model its effect on a piezoelectric resonator. The acoustical equivalent of the superconductor including mass loading effects and terminations are taken into account in the Mason model acoustical equivalent circuit.

We describe a novel microvalve, constructed from polymer chains end-grafted onto opposing surfaces of a narrow slit. The assembly of polymer chains acts as both sensor and valve for microflow control and bypasses the need to construct an external feedback mechanism. This microflow control results from densely grafted chains which repel one another and stretch away from the surface, forming a brush which acts as an elastic and impenetrable layer. The height of a sheared brush increases or decreases depending upon solvent quality, i.e the layer can show a negative Poission's ratio. The discharge through the brushlined conduit is a non-linear function of pressure enabling different modes of valve operation. For brushes which extend moderately into the inter-slit region the valve assembly maintains constant discharge over a wide range of pressure. For brushes which extend far into the inter-slit region the valve assembly cuts off flow above a critical pressure, limiting the maximum discharge.

Biological membranes play a crucial role in signal transduction and information processing as well as in energy conversion. This is owing to the fact that most physiological activities involve some kind of lipid bilayer-based receptor-ligand contact interactions. There are many outstanding examples such as ion sensing, antigen-antibody binding, and ligand/voltage--gated channels, to name a few. One approach to study these interactions in vitro is facilitated by employing artificial bilayer lipid membranes (BLMs). We have focused the efforts on ion and/or molecular selectivity and specificity using newly available self-assembled BLMs on solid support (i.e., s-BLMs), whose enhanced stability greatly aids in research areas of membrane biochemistry, biophysics and cell biology as well as in biosensor designs and molecular devices development. In this paper, our current work along with the experiments carried out in close collaboration with others on s-BLMs will be presented.

Amorphous Tb40Fe60-Fe80B20-Tb40Fe60 sandwich films were prepared by multitarget rf magnetron co-sputtering. Their magnetization and magnetostriction were studied to examine whether magnetic softening of the amorphous TbFe films could be achieved without loosing their giant magnetostriction by introducing the simple sandwich structure. The results revealed that a considerably soft in-plane magnetization (coercive force H≈ 6Oe and the squareness ratio Mr/Ms≈ 0.8) and a huge magnetostriction (λ >500ppm) could be obtained in the sandwich films at room temperature, provided that the thickness of the FeB interlayer was within the range of 10% to 40% of the total film thickness (1 μm).

The magnetomechanical damping capacity of cast and thermally sprayed Fe-Cr based alloys has been investigated using free and forced vibration techniques. The coatings were deposited using a vacuum plasma spraying method and the cast alloys were prepared in a high frequency furnace under an argon atmosphere. Three laboratory devices including a torsion pendulum, a resonant bar and a cantilever were used to cover a wide range of frequencies and amplitudes varying between f = 1Hz to 10 kHz, and ε = 10−6 to 10−3. The damping capacity of the plasma sprayed coatings was found to be comparable to that of cast alloys. Appropriate heat treatments improved the damping capacity of both coatings and cast alloys by several times. The variation of the loss factor as function of the vibration amplitude showed a maximum, but versus frequency exhibited a slightly monotonous character. The magnetic domains were observed using the magneto-optical Kerr effect and their modification under heat treatments was associated with different values of the damping capacities.

158 MHz SAW oscillators coated with organic polymers and zeolites were tested as sensors for monitoring the level of humidity and carbon dioxide in a flowing stream of nitrogen. All coatings exhibited responses to water vapor on the order of kilohertz frequency shifts, while the responses to carbon dioxide were significantly (generally one order of magnitude) smaller. The presence of CO2 dramatically interfered with the detection of water with poly-(ethylenimine) (PEI) coatings. Poly-vinyl pyridine (PVP) coatings showed large responses to water without any interference from CO2; CO2 produced little response whether water was present or not. ZSM-5 coatings also showed no evidence of interference between water and CO2; a detectable response for CO2 is possible in humid nitrogen.

Deposition of crystalline titanium-nickel shape-memory alloys on polymeric substrates is complicated by the elevated temperatures that must be withstood either during deposition or during post-deposition crystallization anneals. In this paper we report results on thin films of titanium-nickel, with Ni-rich compositions, which were prepared by dc magnetron sputtering onto quartz substrates, and onto thin polyimide membranes, at various elevated substrate temperatures between 623K and 703K. All of the as-deposited films possessed ordered bcc microstructures and had nano-scale grain sizes. Films deposited at the higher end of the temperature range displayed familiar two-step transformation behavior in electrical resistivity experiments, with transformation temperatures that were stable with respect to annealing for 22-hrs at 700K. Classic shape-memory was observed for a bilayer consisting of an 7.6 μm thick Kapton® polyimide sheet onto which 3 μm of near-equiatomic TiNi had been sputtered at 703K. By applying a pattern-etch technique to the metallized polymer we were able to fabricate a prototype electrically-excitable thin-film actuating element, potentially applicable to microelectromechanical and biomechanical systems.

The mechanical properties of Ni50Ti50 deposited on Si and 3C-SiC substrates were studied focussing on the interaction of the film and substrate. This interaction determines the transformation characteristics through interface accommodation and mechanical constraints exerted by the substrate stiffness. Substrate stiffness, controlled by the film/substrate thickness ratio, was found to have a substantial influence on the output energy of the film/substrate composite. A switch type composite based on this knowledge was fabricated and tested.

Ti-Ni thin films with three different types of compositions, titanium-rich Ti-Ni, near equiatomic TiNi and nickel-rich Ti-Ni were prepared by sputtering. The sputter-deposited films were annealed at various temperatures between 773 and 973K in order to crystallize. After the heat treatment, the shape memory behavior was examined with a thermomechanical tester. The shape memory behavior of the near equiatomic composition films was not affected by the heat treatment. On the other hand, the shape memory behavior of the other composition films strongly depended on the annealing temperature. As the annealing temperature increases, the martensitic and reverse martensitic transformation temperatures of the nickel-rich films decreased and those of the titanium-rich films increased. These opposite behaviors of the transformation temperatures can be explained by the opposite dependence of the precipitation of the second phase on the annealing temperature. All the nickel-rich films exhibited good shape memory effect over a wide range of stress, while all the titanium-rich films exhibited a small plastic strain only in the stress range where the shape changes associated with both the R-phase and the martensitic transformations were observed.

Axially symmetric coatings of ZnO and PZT have been deposited onto fiber substrates by reactive dc magnetron sputtering. Multi-layer Cr/Au/ZnO/Cr/Au coating structures on optical fibers have been used to make integrated phase modulator devices. An analysis of the structural properties and piezoelectric response of the phase modulator devices will be presented. Microtubes of ZnO and Pt/ZnO/Pt multi-layers have been prepared by coating polyester fibers that act as a fugitive phase. After burning away the polyester fiber, up to 3 cm long micro-tubes with a 23 μm inside diameter and 3 to 9 μm wall thickness were obtained.

Transparent, insulating ZnO thin films have been deposited in-situ by pulsed laser deposition (PLD) from sintered targets. Films were deposited on substrates of fused quartz, <0001> A12O3, polycrystalline and textured (111) Au, at several substrate deposition temperatures (TSubstrate ≤ 700° C) and background oxygen pressures (P ≤ 300 mTorr). Film structure, morphology and electrical properties were characterized by X-ray diffraction, Rutherford backscattering spectrometry, optical properties were characterized by infrared transmission and reflection, and electrical resistivity was measured normal to the films. Films were crystalline, phase pure, and c-axis oriented. ZnO films deposited onto fused quartz and <0001> sapphire showed x-ray rocking curve full width at half maxima of 5° and 0.34°, respectively. The structure of ZnO films deposited on (111) textured Au was sensitive to the degree of texturing in the Au. The resistivity of PLD ZnO films was 61-63 kΩcm which was a factor of three improvement over sputter deposited films. Deposition of Au by both PLD and IBAD showed a negative correlation between the crystalline texturing and film adherence.

Thermally induced interactions between materials in complex microactuator structures were investigated. The device structure contained a combination of a piezoelectric layer (lead zirconate titanate - PZT) an electrode with adhesion layer (Pt/Ti), buffer layer (SiO2 or TiO2), structural material (polysilicon and/or silicon nitride), and sacrificial oxide (SiO2). The presence of a SiO2 sacrificial layer did not affect either the bottom electrode or PZT layer. XRD results showed significant platinum and titanium silicide formation in the Pt/Ti electrode at 700 °C (PZT crystallization temperature) on both polysilicon and silicon nitride structural materials when no buffer layer was used. Auger analysis shows that the Ti adhesion layer oxidizes, that measured levels of silicon increase in the electrode zone, and that electrode elements diffuse into the structural material. Buffer layers of SiO2 (0, 0.1, 0.73, 1.3, 1.5 μm) and amorphous TiO2 (0.065 μm) were inserted between the electrode and the structural material. XRD and sheet resistance measurements demonstrated that SiO2 thicknesses greater than 0.73 μm reduced pyrochlore formation in the PZT and reduced the degradation of the electrode. However, this thickness was incompatible with overall surface micromachining processes. The TiO2 layer effectively prevented pyrochlore formation and electrode degradation, while being compatible with overall actuator processing.

A free standing cantilever beam consisting of a support structural material (polysilicon/silicon nitride), a piezoelectric PZT ceramic layer, and metal electrode layers has been analyzed. Beam theory and finite element analysis were used to model the electric field induced deflections of this structure, and provided information as to how material choices influenced actuator function. Both support material and PZT thicknesses varied from 0-1.0 gim, and bulk piezoelectric coefficients and elastic moduli were assumed. The beam theory uses known (or assumed) material properties to predict actuator responses. Conversely, if device responses can be measured, material properties may be inferred from the theory. For a PZT thickness of 0.3 μm, a core layer thickness of 0.13 μm was found to maximize displacement. Also, the force output was found to be more dependent on the core thickness than that of the PZT. This information can then be used to predict the response of a more complex microactuator.

In a previous work. composites of BSTO combined with other nonelectrically active oxide ceramics have been formulated and have demonstrated adjustable electronic properties which can be tailored for use in various electronic devices. One application has been for use in phased array antennas and insertion has been accomplished into several working antenna systems. To further accommodate the frequencies required by these phased array antennas, thin films of the composites have been fabricated using a Krypton Fluoride excimer laser as an ablation source. The electrical properties, including the dielectric constant and the tunability (change in the dielectric constant with applied voltage) have been measured. The results have been compared to those obtained for the bulk, ceramic composites and other BSTO/oxide composite thin film structures.

Thin film layers of shape memory alloys and ferroelectric ceramics can produce a family of ‘smart’ heterostructures capable of performing both sensing and actuating functions. Important issues in the synthesis of these active structures are the ability to generate the appropriate crystalline phases of each material, while producing defect-free homogeneous high quality films. The compatibility of sol-gel processed Pb(Zr,Ti)O3 (PZT) thin films with thin film shape memory effect TiNi substrates were investigated. Thin film TiNi was deposited on quartz substrates by physical sputter deposition utilizing a TiNi target in a ultra-high vacuum chamber, and followed by in-situ vacuum annealing. PZT was deposited on TiNi by sol-gel and spin coating processes. The ferroelectric tetragonal phase of PZT was obtained by a 600 °C anneal for 5m in air. The heterostructures were nominally defect-free, unlike those obtained through deposition onto bulk TiNi substrates.x

The piezoelectric properties of lead zirconate titanate (PZT) thin films deposited on thick silicon substrates and thin silicon membranes were investigated using optical interferometry. The effect of the geometrical constraints and clamping effects on the piezoelectric response is discussed. The study of the dielectric permittivity and the loss as a function of the amplitude of the alternating electric field reveals that extrinsic contributions to the dielectric permittivity become active at large fields. The DC electric field has the effect of freezing out the extrinsic contributions. The influence of the dielectric loss on the piezoelectric properties is discussed.

Pyroelectric thin film detectors have advantages of wavelength independent sensitivity, room temperature operation and direct incorporation with integrated circuit amplifiers. Pyroelectric thin films with good quality have be prepared by many advanced thin film technologies [1-2]. The responsivity of pyroelectric thin film detectors is dependent on the thermal properties of the substrate, on which pyroelectric thin film detectors are prepared. The heat conduction in the detectors was investigated using the one-dimensional heat flow equation and the expressions describing the detectors performance were derived for pyroelectric thin films detectors with multilayer structure. The numerical simulation showed that the pyroelectric thin film detectors need effective heat isolation. If the air gap could be the heat isolation layer, which is between the bottom electrode and substrate, the iesponsivity of detectors would be higher than that of detectors which have no heat isolation in certain modulation frequency range.

The functional properties of Shape Memory Alloys (SMA's) are used succesfully at present in a variety of industrial and medical applications. The use of these materials in smart structures is now emerging in the field of aeronautic/space technology. Many applications require higher operating temperatures than available to date, or higher cooling rates and/or a higher number of cycles. For this purpose the properties and fabricability of commercial alloys as Ni-Ti-(X), Cu-Al-Ni or Cu-Zn-Al are being adjusted and improved. Other feasible alloys are being developed. The research and development is directed towards the control of the stress, strain, temperature and time dependence of shape memory properties for a stable in-service behaviour. In this paper the various approaches taken up in recent years by academic and industrial laboratories for developing high temperature SMA's are reviewed.

NiTiHf and NiAI have shown the potential for development as high temperature shape memory alloys with transformation temperatures of 150°C or higher. However, various engineering considerations must be addressed before these systems can be used as practical high temperature shape memory alloys. These considerations include: fabricability, phase stability, mechanical stability, and cost. NiTiHf is attractive from a cost standpoint, although its fabricability must still be demonstrated on larger heats of material. The phase stability and mechanical stability of NiTiHf are unknown. NiAl requires great improvements in both fabricability and phase stability. The mechanical stability and costs for producing NiAI shape memory alloys are still unclear.