Screen Printed PZT Thick Films Using Composite Film Technology

A spin coating composite sol gel technique for producing lead zirconate titanate (PZT) thick films has been modified for use with screen printing techniques. The resulting screen printing technique can be used to produce 10 ?m thick films in a single print. The resultant films are porous but the density can be increased through the use of repeated sol infiltration/pyrolysis treatments to yield a high density film. When fired at 710°C the composite screen printed films have dielectric and piezoelectric properties comparable to, or exceeding, those of films produced using a 'conventional' powder/glass frit/oil ink and fired at 890°C

Development of a cantilever beam generator employing vibration energy harvesting

This paper details the development of a generator based upon a cantilever beam inertial mass system which harvests energy from ambient environmental vibrations. The paper compares the predicted results from Finite Element Analysis (FEA) of the mechanical behaviour and magnetic field simulations and experimental results from a generator. Several design changes were implemented to maximise the conversion of magnetic energy into generated power and a maximum power output of 17.8µW was achieved at a resonant frequency of 56.6Hz and an applied acceleration of 60mg (g = 9.81ms-2)

The action of rennin on casein The disruption of the k-casein complex

Approximately 30% of the nitrogen of κ-casein was soluble at pH 4·7 after the protein had been treated with rennin at pH 7 while approximately 10% was soluble in 12% trichloroacetic acid (TCA). The material soluble in 12% TCA appeared at a slower rate initially than did the nitrogen soluble at pH 4·7 but as the reaction proceeded it was released more rapidly. Treating κ-casein with urea, or repeated precipitation of the protein at pH 4·7, caused the formation of material insoluble at pH 7, apparently para-κ-casein. Both treatments appeared to free the same soluble fraction as does rennin acting in low concentration or for a short time. Low concentrations of rennin (0·07 μg/ml) released only part of the available soluble nitrogen from 2% solutions of whole casein at pH 7. Heating the reaction mixture appeared to restore the casein complex, the restoration being less complete the longer the reaction had proceeded. It is suggested that κ-casein is not a single protein but a complex, and that the action of rennin is first to open the secondary bonds responsible for the stability of this comple

Metallic Triple Beam Resonator with Thick-film Printed Drive and Pickup

A triple beam resonator fabricated in 430S17 stainless steel with thick-film piezoelectric elements to drive and detect the vibrations is presented. The resonator substrate was fabricated by a simultaneous, double-sided photochemical etching technique and the thick-film piezoelectric elements were deposited by a standard screen-printing process. The combination of these two batch-fabrication processes provides the opportunity for mass production of the device at low cost. The resonator, a dynamically balanced triple beam tuning fork (TBTF) structure 23.5 mm long and 6.5 mm wide, has a favoured mode at 4.96 kHz with a Q-factor of 3630 operating in air

Conjugatable water-soluble Pt(ii) and Pd(ii) porphyrin complexes: Novel nano- and molecular probes for optical oxygen tension measurement in tissue engineering

Measurement of oxygen tension in compressed collagen sheets was performed using matrix-embedded optical oxygen sensors based on platinum(II) and palladium(II) porphyrins supported on polyacrylamide nanoparticles. Bespoke, fully water-soluble, mono-functionalised Pt(II) and Pd(II) porphyrin complexes designed for conjugation under mild conditions were obtained using microwave-assisted metallation. The new sensors display a linear response (1/τ vs. O₂) to varying oxygen tension over a biologically relevant range (7.0 × 10⁻⁴ to 2.7 × 10⁻¹ mM) in aqueous solutions; a behaviour that is maintained following conjugation to polyacrylamide nanoparticles, and following embedding of the nanosensors in compressed collagen sheets, paving the way to innovative approaches for real-time resolution of oxygen gradients throughout 3D matrices useful for tissue regeneration

Verification of shrinkage curvature code prediction models

An attempt is made to theoretically and experimentally verify the shrinkage curvature models presented in Eurocode 2 and BS 8110. These codes claim that the models originally derived and proven for uncracked sections are suitable, with modification, for predicting the behaviour of cracked sections, although this claim has never been proven experimentally. To achieve verification, an alternative theoretical approach is initially proposed in this paper. In this theoretical model, the effect of shrinkage, creep and the variation in the neutral axis position of the section are taken into account. The stresses developed in the steel and concrete at a cracked section according to this theoretical model are then applied to a finite-element (FE) model representing a portion of the beam from the crack to mid-way between the crack and an adjacent crack. Ultimately, the mean curvature is determined. Experimentally, pairs of beams were cast and subjected to a level of flexural loading to produce a stabilised crack pattern in the constant-moment zone. The behaviour of the beams was monitored for up to 180 days. For any pair of beams, one beam was cast using a high-shrinkage concrete and the other with a low-shrinkage concrete. Each concrete type, however, exhibits similar creep. Therefore, shrinkage curvature can be obtained by subtracting the long-term movements of one beam from the other. These experimentally defined curvatures were compared with the mean curvatures obtained from the FE analysis. The comparison showed reasonable agreement. The curvatures were also compared with uncracked and cracked curvatures predicted by the codes. The curvatures derived in this investigation fell within the boundaries of the uncracked and cracked curvatures predicted by the codes and, for the fully cracked case, the curvatures were closer to the uncracked boundary

Reliable UHF long-range textile-integrated RFID tag based on a compact flexible antenna filament

This paper details the design, fabrication and testing of flexible textile-concealed RFID tags 1 for wearable applications in a smart city/ smart building environment. The proposed tag designs aim 2 to reduce the overall footprint, enabling textile integration whilst maintaining the read range. The 3 proposed RFID filament is less than 3.5 mm in width and 100 mm in length. The tag is based on an 4 electrically small (0.0033λ 2) high-impedance planar dipole antenna with a tuning loop, maintaining a 5 reflection coefficient less than −21 dB at 915 MHz, when matched to a commercial RFID chip mounted 6 alongside the antenna. The antenna strip and the RFID chip are then encapsulated and integrated in 7 a standard woven textile for wearable applications. The flexible antenna filament demonstrates a 1.8 8 dBi gain which shows a close agreement with the analytically calculated and numerically simulated 9 gains. The range of the fabricated tags has been measured and a maximum read range of 8.2 m was 10 recorded at 868 MHz. Moreover, the tag's maximum calculated range at 915 MHz is 18 m, which 11 is much longer than the commercially available laundry tags of larger length and width, such as 12 Invengo RFID tags. The reliability of the proposed RFID tags has been investigated using a series 13 of tests replicating textile-based use case scenarios which demonstrates its suitability for practical 14 deployment. Washing tests have shown that the textile-integrated encapsulated tags can be read after 15 over 32 washing cycles, and that multiple tags can be read simultaneously while being washed

A micro electromagnetic generator for vibration energy harvesting

Vibration energy harvesting is receiving a considerable amount of interest as a means for powering wireless sensor nodes. This paper presents a small (component volume 0.1 cm3, practical volume 0.15 cm3) electromagnetic generator utilizing discrete components and optimized for a low ambient vibration level based upon real application data. The generator uses four magnets arranged on an etched cantilever with a wound coil located within the moving magnetic field. Magnet size and coil properties were optimized, with the final device producing 46 µW in a resistive load of 4 k? from just 0.59 m s-2 acceleration levels at its resonant frequency of 52 Hz. A voltage of 428 mVrms was obtained from the generator with a 2300 turn coil which has proved sufficient for subsequent rectification and voltage step-up circuitry. The generator delivers 30% of the power supplied from the environment to useful electrical power in the load. This generator compares very favourably with other demonstrated examples in the literature, both in terms of normalized power density and efficiency