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Optimised part programs for excimer laser-ablation micromachining directly from 3D CAD modelsMutapcic, Emir, n/a January 2006 (has links)
Fabrication of a 3D structure and surface texture using excimer laser mask
projection ablation processes typically requires the machine operator to develop a specific
NC part program for the desired structure geometry, and also incorporate appropriate
machine parameters to achieve the desired surface finish. The capability of the laser
ablation process could therefore be significantly improved by developing a CAD/CAM
system that automatically generates the NC part program using the 3D information of the
CAD model of the desired structure. Accordingly, the focus of this research was to
develop such a system that is, an effective CAD/CAM system specifically for excimer
laser mask projection micromachining tools.
To meet these requirements, a unique combination of commercially available
systems was used to develop the new CAD/CAM system. The systems used comprised of
a computer aided, feature based parametric design system (SolidWorks), together with
its extended programming capabilities based on Automated Programming Interface (API)
functions for Windows applications, and Visual Basic (VB) 6.0 programming utilities.
The system's algorithms use a novel methodology to extract the 3D geometry of a
microstructure. Two different techniques have been developed to extract the 3D data.
First, where 3D geometry information from a CAD model was defined as a Stereolithography
(STL) file, and second, where this information has been contained in a set of
bit-map (BMP) files that represent a sliced or layered structure of a CAD model. Based
on this, first an algorithm to create NC part programs to support Step-and-repeat
micromachining technique was developed and then successfully extended to be applicable
for another commonly used micromachining method, Workpiece-Dragging technique.
The systems algorithms for both techniques are based on the raster-colour
programming technique, resulting in substantially reduced mathematical complexity and
computational time. This is the first time this approach has been used to support direct
conversion of 3D geometry from a CAD model into an NC part program compatible with
the excimer laser CNC controller. 2D mathematical models for controlling edge and
stitching errors were also implemented in the system.
An additional technique, named as 'Common Nest' has been developed with the
aim to enable automatic NC part programming when microstructure design to be
completed successfully, requires use of multiple complex mask patterns as a projection
tool instead of just a single square aperture.
The effectiveness of the system was verified by NC part program generation for
several 3D microstructures and subsequent machining trials using polycarbonate (PC) and
Polyethylene terephthalate (PET), and optimised processing parameters. Excellent
agreement was obtained between the laser machined geometries and the microstructure
CAD models. The Laser Scanning Confocal Microscope (LSCM) measured the lateral
dimensions tolerance of 2m.
The system was also successfully applied for a practical micro-engineering
application, for the development of a microfluidics cell transportation device.
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Direct Fabrication of Planar Grating by Ultrafast Laser BeamVenkatakrishnan, K., Hee, C.W., Sivakumar, N.R., Ngoi, Kok Ann Bryan 01 1900 (has links)
Femtosecond laser pulse has been used for the machining of the gratings primarily due to its superior advantages over conventional continuous wave (CW) and long pulse lasers for micromachining. In this paper, we develop a novel technique for the fabrication of planar gratings by colliding two beams to generate interference fringes. This technique is simple, fast and low cost. We have successfully fabricated planar gratings on a copper substrate. / Singapore-MIT Alliance (SMA)
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Microfabricated Optical Sensor Probe for the Detection of Esophageal CancerChinna Balareddy, Karthik Reddy 2009 May 1900 (has links)
Cancer is a class of diseases in which a group of cells grow uncontrollably, destroy surrounding tissue and eventually spread to other parts of the body, often leading to death. According to the American Cancer Society cancer causes accounts for 13% of all deaths. Much of the time cancer can be treated if diagnosed early. Considerable study is currently being undertaken to investigate tissue properties and their use in detecting cancer at an early stage through non invasive and non surgical methods. Oblique Incidence Diffuse Reflectance Spectrometry (OIDRS) is one such method.
This thesis reports the design, fabrication and testing of a new miniaturized optical sensor probe with "side viewing" capability for oblique incidence diffuse reflectance spectrometry. The sensor probe consists of a lithographically patterned polymer waveguides chip and three micromachined positioning substrates and source/collection fibers to achieve 45 degree light incidence and collection of spatially resolved diffuse reflectance.
The probe was tested at the Mayo Clinic in Rochester Minnesota. The test results show that the probe is capable of collecting data which can be analyzed to select image features to differentiate the cancerous tissue from non cancerous tissue. Using these probes, diffuse reflectance of human esophageal surface has been successfully measured for differentiation of cancerous tissues from normal ones.
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Feedback Controlled High Frequency Electrochemical MicromachiningOzkeskin, Fatih Mert 10 October 2008 (has links)
Microsystem and integrated circuitry components are mostly manufactured using
semiconductor technologies. Fabrication using high strength metals, for demanding
aerospace, mechanical, or biomedical applications, requires novel technologies which
are different from those for silicon. A promising mass production method for
micro/meso scale components is electrochemical micromachining.
The complex system, however, requires high precision mechanical fixtures and
sophisticated instrumentation for proper process control. This study presents an
electrochemical micromachining system with a closed-loop feedback control
programmed using a conditional binary logic approach.
The closed-loop control is realized using electrical current as the dynamic
feedback signal. The control system improves material removal rate by 250% through
optimizing inter electrode gap and provides robust automation reducing machining
variation by 88%. The new system evokes production of higher quality
microcomponents. Workpiece damage is reduced by 97% and increased feature
sharpness is observed.
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Design and Electromechanical Analysis of Surface-Micromachined Tunable CapacitorChou, Che-Ya 12 September 2007 (has links)
This paper aims to design and simulate the surface-micromachining micro tunable capacitor for parameters optimization. This work also creates an equivalent circuit model of micro tunable capacitor and proceeds relative electromechanical analysis, including the distribution of field and charge, resonant frequency and pull-in voltage analysis. This micro tunable capacitor is constructed by one suspended top metal plate and two stationary bottom metal plates (one is signal electrode and the other one is bias electrode). By driving electrostatic force, the gap between top and bottom electrodes will be changed and results in a variation of capacitance. To increase the tuning range, the micro tunable capacitor with two different gap space will be presented in this research.
High frequency analysis, equivalent circuit analysis and electromechanical dynamic analysis are using Ansoft HFSS, Agilent ADS and the IntelliSuite software respectively. Through these simulation and analysis, it is possible to obtain the optimized specification of micro tunable capacitor. The quality factor (Q) and the pull-in voltage extracted by simulation software well match to the measured results; thus, the function of the analysis method and equivalent model adopted in this thesis can be demonstrated.
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Fabrication technology approaches to micromachined synthetic jetsCoe, David James 05 1900 (has links)
No description available.
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Experimental study of micro-nano-scale cutting of aluminum 7075 and P20 mold steelNg, Chee Keong. January 2005 (has links) (PDF)
Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2005. / Lackey, Jack, Committee Member ; Kurfess, Thomas, Committee Member ; Melkote, Shreyes, Committee Chair. Includes bibliographical references.
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Computational and experimental investigations of laser drilling and welding for microelectronic packagingHan, Wei. January 2004 (has links)
Thesis (Ph. D.)--Worcester Polytechnic Institute. / Keywords: Optoelectronic holography; Microwelding; Microelectronic packaging; Microdrilling; Laser micromachining; Computational modeling. Includes bibliographical references (p. 204-212).
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Piezoresistive pressure sensor with integrated amplifier realized using metal-induced laterally crystallized polycrystalline silicon /Li, Gang. January 2004 (has links)
Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2004. / Includes bibliographical references. Also available in electronic version. Access restricted to campus users.
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Degree-per-hour mode-matched micromachined silicon vibratory gyroscopesZaman, Mohammad Faisal. January 2008 (has links)
Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Dr. Farrokh Ayazi; Committee Member: Dr. Mark G. Allen; Committee Member: Dr. Oliver Brand; Committee Member: Dr. Paul A. Kohl; Committee Member: Dr. Thomas E. Michaels.
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