1,720,993 research outputs found
Development of a thick-film magnetostrictive material: formulation and characterisation
No full textA magnetostrictive thick-film based upon the giant magnetostrictive material Terfenol-D is developed and characterised for use as a screen-printable actuator material. It is envisaged that the material would be used to provide actuation in micromachined devices. The potential advantages of a screen-printable magnetostrictive material over the existing technologies are: that no direct electrical connection is needed to the material, unlike with piezoelectric materials; that the printing process can readily produce thicker layers than the deposition techniques used to produce thin-films can reasonably produce; devices with smaller and more intricate material geometry are achievable with the printing process than can be obtainable by the machining of bulk material. A review of currently published magnetostrictive technologies and their applications is presented and, although no other work currently exists regarding magnetostrictive materials in thick-film form, comparisons are drawn between both thin-film and adhesive-bonded composite forms and the novel thick-film formulation presented here. The development and characterisation process of a magnetostrictive thick-film paste suitable for printing onto alumina substrates is presented, this includes the novel technique of adding a filler material to the paste to permit the use of larger active particles within the thick-film paste. This magnetostrictive thick-film technology is then migrated onto silicon substrates and further characterised. The route of further development and refinement of the material is outlined, and potential applications in the area of micromachined devices are proposed.</p
Use of a novel keypad biometric for enhanced user identity verification
No full textIn everyday life many actions are secured and/or authenticated by use of a secret personal identification number (PIN). This paper reports an improvement to the security afforded by a numeric PIN system through the addition of a covert biometric identification process. This biometric identification process is achieved through the use of a modified keypad incorporating force sensors within the individual keys, these sensors permit the dynamic measurement of applied force and key-press timings, providing an advantage over existing keystroke dynamic techniques which rely on time-domain information only. Details of the experimental setup used are given, and the results from initial tests are reported. In these tests an equal error rate of approximately 10% is obtained and a false acceptance rate of 15% with a corresponding false rejection rate of 0% has been shown
Evaluation of glass frit binder materials for use in thick-film magnetostrictive actuators
No full textThis paper presents research carried out at the University of Southampton into the development of a magnetostrictive thick-film material suitable for use with silicon micro-machined devices. This form of magnetostrictive material has previously been deposited onto alumina substrates and this paper reports further work on migrating the technology onto silicon. The evaluation of two alternative glass frits for use as the binder within the thick-film is reported. The correct choice of the binder material is important because it is responsible for binding the active material within the film also adhering the film to the substrate. A series of tests have been applied to samples fabricated using various glass frits to assess their mechanical properties and suitability for use in micro-actuator applications
Thick-Film Actuation Technologies For MEMS Applications
No full textThis paper compares two thick-film actuation technologies and assesses their suitability for use within micromachined devices. The materials are a piezoelectric composition, which exhibits a d33 coefficient of the order of 130pC/N, and a magnetostrictive material which possess a magnetostriction of 4.4ppm at a magnetic field of 11.5kA/m. Examples of their application in micromachined devices are also given
The effect of the type of illumination on the energy harvesting performance of solar cells
No full textThis paper presents the effect of the illumination type on the performance of photovoltaic energy harvesting for application in buildings. A range of different types of solar cells are available to suit differing illumination sources and intensities. Modules made from polycrystalline silicon, amorphous silicon and dye-sensitized TiO2 were investigated under illumination from incandescent, fluorescent, white light LED and RGB colour-controllable LED light sources in this paper. It is shown that it is important to select the solar cell to suit the type of light. In this paper, the maximum power points of four types of solar cell have been investigated under three different electrical light sources for various illumination levels allowing the selection of the optimum solar cell type for a given combination of electrical light source and a particular illumination level. An analysis of the effect of varying the spectral composition of the illumination is achieved by using a colour-controllable LED to provide the primary colours of white light. Generally, most power is harvested by solar cells under incandescent illumination sources followed by compact fluorescent (CFL) and then LED. The amorphous-Si solar cells tested show a similar power output under all three illumination sources, therefore a device using these should perform consistently under all lighting sources, whereas the poly-crystalline silicon solar cell tested shows a significant difference between incandescent and CFL/white light LED sources which could restrict operation to just incandescent lighting
Effects of the binder material on the mechanical properties of thick-film magnetostrictive materials
No full textThis paper presents research carried out at the University of Southampton into the development of a magnetostrictive thick-film material suitable for use with silicon micromachined devices. This form of magnetostrictive material has previously been deposited onto alumina substrates and this paper reports further work on migrating the technology onto silicon. The evaluation of two alternative glass frits for use as the binder within the thick film is reported. The correct choice of the binder material is important in a thick-film material because it is responsible for binding the active material within the thick film into a composite material and also adhering the film to the substrate. A series of tests have been applied to samples fabricated using various glass frits to assess their mechanical properties and suitability for the micro-actuator applications
Dataset for dispenser printed sound emitting fabrics for applications in the creative fashion and smart architecture industry
No full textThis paper reports direct write dispenser printed sound emitting smart fabrics aimed at creative fashion applications and smart architecture. Planar spiral speakers generate a membrane vibration and so emit sound when driven from an a.c. audio source if a magnet is in close proximity to the spiral. The speaker designs were printed on polyester cotton fabric and produced a measured peak sound output level of 85 dB referenced to a reference sound pressure in air of 2×10-5 Pa. The printed fabric speakers demonstrate a wide frequency response from 20 Hz to 20 kHz. This research demonstrates a straightforward fabrication method to achieve sound emission from a fabric. The fabrication process requires a processing temperature of 130 oC for 10 minutes which is compatible with many fabrics. It also offers complete freedom of the creative design. This fabrication method is a direct write technique offering no waste and achieves a conductor resistivity of 7.69×10-6 ?·m . This paper reports on the theory and the manufacturing technology to achieve direct write dispenser printed planar spiral speakers on fabrics. </span
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