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Volume 151
Issue 2
IEE Proceedings - Science, Measurement and Technology
Volume 151, Issue 2, March 2004
Volumes & issues:
Volume 151, Issue 2
March 2004
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- Author(s): Deepak Uttamchandani
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 151, Issue 2, page: 53 –53
- DOI: 10.1049/ip-smt:20040263
- Type: Article
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- Author(s): D.F. Moore and J.A. Williams
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 151, Issue 2, p. 54 –59
- DOI: 10.1049/ip-smt:20040046
- Type: Article
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Bulk micromachining silicon to form microbeams is a common procedure in MEMS fabrication. A focused laser is used to cut patterns directly in a silicon nitride or silicon carbide mask layer to prototype new structures and test geometries. In the past two years this flexible approach has been used as the basis of a practical undergraduate course in which students (a) design shapes using CAD, (b) cut them using the laser system, (c) micromachine in a clean room using anisotropic wet etching, (d) take microscope images, and (e) use a mechanical profilometer to test the silicon nitride microbeams and measure the elastic modulus. This teaching approach is outlined and the utility of hands-on practical work in MEMS education is assessed. - Author(s): J. Zawadzka ; L. Li ; D. Uttamchandani
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 151, Issue 2, p. 61 –66
- DOI: 10.1049/ip-smt:20040180
- Type: Article
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A vertically self-assembled, fibre optic variable optical attenuator (VOA) incorporating a microshutter placed between the end faces of two closely spaced optical fibres is reported. The position of the microshutter with respect to the optical fibre end face was controlled by a nanostepping MEMS motor that was composed of a microactuator array and microsprings. Optical and mechanical tests were performed on the device. It was found that it is possible to obtain a 45 dB dynamic range with an attenuation time of 36 ms. A model of the microshutter was constructed as a plane plate structure with evenly distributed etch holes that are artefacts of the manufacturing process. Geometric and diffraction image analyses were performed and the attenuation characteristic of the system was assessed. It is thus shown that using commercially accessible foundries it is possible to fabricate a high precision VOA for free-space microoptics applications. - Author(s): W. Huang ; R.R.A. Syms ; J. Stagg ; A. Lohmann
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 151, Issue 2, p. 67 –75
- DOI: 10.1049/ip-smt:20040036
- Type: Article
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A tuning element has been constructed using micro-opto-electro-mechanical systems (MOEMS) technology for Littman configuration external cavity tunable lasers. The device is fabricated by deep reactive ion etching of bonded silicon-on-insulator, using a single layer of patterning to integrate a fixed grating and a mirror that is rotated about a virtual pivot by an electrostatic comb drive. The mirror is mounted on a compound flexure. To ensure mode-hop free tuning, the pivot point should lie at the intersection of the mirror and grating planes. Candidate elastic suspensions are compared, and a combination of a cantilever and a portal spring, is selected. Interferometric measurements of electromechanical performance show that the mirror is rotating about a suitable remote point. Preliminary data are given for a Littman external cavity laser operating with a fixed MOEMS structure. - Author(s): L. Li and D. Uttamchandani
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 151, Issue 2, p. 77 –84
- DOI: 10.1049/ip-smt:20040099
- Type: Article
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The design and evaluation of a MEMS-based chopper for optical measurements is reported. The overall dimensions of the chopper, including the microactuators and micromechanical suspension, are 1200×1200 μm making it very compact. The comb-actuator driven chopper, designed for use in conjunction with fibre optics, has been fabricated in silicon-on-insulator material which has been back-etched to create an optical path through the thickness of the substrate. General electro-mechanical design considerations, including factors to minimise the side instability of the comb drive, are described. Finite element modelling (FEM) of the chopper is backed up by simple theoretical results, and the results from the theoretical work verify the findings from the FEM. Optical modelling of the chopper is also reported. Experimentally, the device was driven from 0-34 V DC to measure its static characteristics. For dynamic characterisation, the device was operated from 0-28 V AC and its fundamental resonant frequency was measured to be 3 kHz. Experimental evaluation of the device characteristics are shown to closely match the theoretical predictions. - Author(s): A.S. Holmes
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 151, Issue 2, p. 85 –92
- DOI: 10.1049/ip-smt:20040374
- Type: Article
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Excimer laser micromachining by mask projection with half-tone masks has been used to define deep structures with complex surface profiles in cross-linked SU-8 photoresist. A simple algorithm has been developed to derive the required mask transmission function given the material etch characteristics and the desired surface profile. This algorithm has been shown to give reasonable profile accuracy for structures with heights of up to about 150 μm. The technique has been used in the fabrication of the rotor blades for an axial-flow microturbine. - Author(s): S. Lucyszyn
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 151, Issue 2, p. 93 –103
- DOI: 10.1049/ip-smt:20040405
- Type: Article
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A review of radio frequency microelectromechanical systems (RF MEMS) technology, from the perspective of its enabling technologies (e.g. fabrication, RF micromachined components and actuation mechanisms) is presented. A unique roadmap is given that shows how enabling technologies, RF MEMS components, RF MEMS circuits and RF microsystems packaging are linked together; leading towards enhanced integrated subsystems. An overview of the associated fabrication technologies is given, in order to distinguish between the two distinct classes of RF microsystems' component technologies; non-MEMS micromachined and true MEMS. An extensive literature survey has been undertaken and key papers have been cited; from these, the motivations behind different RF MEMS technologies are highlighted. The importance of understanding the limitations for realising new and innovative ideas in RF MEMS is discussed. Finally, conclusions are drawn as to where future RF MEMS technology may lead. It is likely that the switch will continue to be the most important RF MEMS component, with future work investigating its enhanced functionality, subsystem integration and volume production. The focus of RF MEMS circuits will shift from the digital phase shifter to high-Q tuneable filters. - Author(s): A.J. Gallant and D. Wood
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 151, Issue 2, p. 104 –109
- DOI: 10.1049/ip-smt:20040406
- Type: Article
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Micromachined two-gap widely tunable capacitors have been fabricated with a tuning ratio of 7.3:1. The design presented requires sub-micron air gaps to enable low voltage operation and to reduce electrode curvature during operation. Photoresist and titanium have been evaluated for use as sacrificial layers in these devices. Organic deposits remaining after the sacrificial etching of photoresist make it inappropriate for use as a primary sacrificial layer. Titanium, however, etches cleanly and introduces additional surface topology into the capacitive electrodes which is beneficial for stiction avoidance. Stiction-free released device yields up to 90% have been observed. - Author(s): A.J. Walton ; W. Parkes ; J.G. Terry ; C. Dunare ; J.T.M. Stevenson ; A.M. Gundlach ; G.C. Hilton ; K.D. Irwin ; J.N. Ullom ; W.S. Holland ; W.D. Duncan ; M.D. Audley ; P.A.R. Ade ; R.V. Sudiwala ; E. Schulte
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 151, Issue 2, p. 110 –120
- DOI: 10.1049/ip-smt:20040088
- Type: Article
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The design and fabrication is described of the prototype IR detector for the SCUBA-2 80×80 pixel array (Submillimetre Common User Bolometer Array), which is to be mounted on the James Clerk Maxwell Telescope in Hawaii. The detector technology is based on silicon micromachining, with transition edge sensors (TES) being used to detect incoming radiation with wavelengths of 450 and 850 μm. Each TES is located on a λ/4 silicon brick suspended on a silicon nitride membrane and supported by a silicon micromachined waffle. Low-temperature indium bump bonding connects each TES to a SQUID multiplexer chip. The paper details the design considerations and the technology used to fabricate the detector wafer. - Author(s): H. Yoshioka ; H. Hashizume ; H. Shinn
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 151, Issue 2, p. 121 –125
- DOI: 10.1049/ip-smt:20040375
- Type: Article
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Future ultraprecision manufacturing systems will require intelligent machine tools equipped with effective in-process monitoring systems for the machining environment. To meet these requirements, a sensor is urgently required that combines multifunctionality, reliability, sensitivity and compactness. It is particularly difficult to monitor the machining status during ultraprecision machining, because the energy emissions and cutting forces are very small in comparison to conventional machining processes. A thermometry-type in-process microsensor is proposed to solve this problem. The proposed microsensor is made using a microfabrication process that is normally used in semiconductor production. The sensor size is 520×250 μm and the line width of the sensor device is 5 μm. The developed microsensor is mounted directly onto the surface of a tool tip at a distance of 0.8 mm from the cutting edge. The performance of the developed microsensor is investigated through a series of ultraprecision cutting experiments. - Author(s): D. Petit ; D. Atkinson ; S. Johnston ; D. Wood ; R.P. Cowburn
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 151, Issue 2, p. 127 –130
- DOI: 10.1049/ip-smt:20040167
- Type: Article
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We report on the room temperature performance of bismuth Hall probes fabricated using focused ion beam milling. The sensitivity of the devices has been studied for a wide range of sizes (50 nm–10 μm) and for three film thicknesses: 29, 78 and 152 nm. It was found that the sensitivity of such probes is not limited by Johnson noise and is strongly dependent on both the thickness of the film and the dimensions of the device. The results are discussed in terms of practical applications to Scanning Hall Probe Microscopy. - Author(s): M. Stuchlik ; P. Krecmer ; S.R. Elliott
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 151, Issue 2, p. 131 –136
- DOI: 10.1049/ip-smt:20040073
- Type: Article
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Results on a system exhibiting all-optical actuation are reported. Clamped silicon cantilevers, coated on top with thin films of chalcogenide glasses, reversibly deflect upwards or downwards when illuminated with linearly polarised light with the electric vector of the light being respectively parallel or perpendicular to the cantilever axis. The response is strongly wavelength selective, the maximum, and fastest, response being achieved for illumination with light having a photon energy comparable to the bandgap energy of the semiconducting amorphous chalcogenide layer. This effect can form the basis of micro-opto-mechanical system devices, controlled by varying the intensity, wavelength or polarisation direction of the incident light.
Editorial: MEMS and microsystems engineering
Laser prototyping of MEMS structures and SiN cantilevers: experience teaching a practical undergraduate course
Characterisation of a nanostepper driven optical shutter for application in free-space microoptics
Precision MEMS flexure mount for a Littman tunable external cavity laser
Design and evaluation of a MEMS optical chopper for fibre optic applications
Excimer laser micromachining with half-tone masks for the fabrication of 3-D microstructures
Review of radio frequency microelectromechanical systems technology
Sacrificial layers for widely tunable capacitors
Design and fabrication of the detector technology for SCUBA-2
In-process microsensor for ultraprecision machining
Room temperature performance of submicron bismuth Hall probes
Micro-nano actuators driven by polarised light
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