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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Design of chemical sensors based on calixarene and fluorescein octadecyl ether octadecyl ester : from ion selective electrode to fluorescent optode

Lam, Yiu Sing 01 January 2000 (has links)
No description available.
42

Characterization of HFAPNB and PHOST as a polymer sensing layer in an interferometric evanescent wave sensor

Dennis, Karla Ann. January 2009 (has links)
Thesis (M. S.)--Chemical Engineering, Georgia Institute of Technology, 2010. / Committee Chair: Henderson, Clifford L.; Committee Member: Ludovice, Pete; Committee Member: Ralph, Stephen E.. Part of the SMARTech Electronic Thesis and Dissertation Collection.
43

MEMS based microfluidic structure for biological and chemical sensor array /

Sohn, Young-Soo, January 2001 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references (leaves 112-123). Available also in a digital version from Dissertation Abstracts.
44

The development of an optical position sensor

Kinney, Stuart January 1998 (has links)
A theoretical study of an electrically passive, loss-compensated, optical position sensor is the goal of this project. Optical fiber sensors exploit light as the information carrier. Fiber-optic sensors consist of a constant light source launched into an optical fiber and transmitted to another point at which a measurement is made.In the proposed optical position sensor, a Light Emitting Diode (LED) produces a constant beam of light, which is channeled through an optical fiber to a Graded Index (GRIN) lens. This lens makes all the light rays parallel to one another, a process called collimation. The light then enters a polarizer which is a lens that further orders the light rays in a process called polarization.Then the light enters a chamber in which a doubly refracting (birefringent) crystal is situated. The crystal is a wedge, and thus has a varying thickness throughout its length. The light beam strikes the crystal, sending a spectrum, or spectral signature, that is distinct to the particular thickness of the crystal. That signature goes directly from the chamber housing the crystal into a lens called an analyzer which orders the light again through polarization. Then the light goes into another GRIN lens, and this GRIN lens focuses the light onto an optical fiber, which transmits the particular spectral signature of this light to an optical spectrum analyzer (OSA). The OSA uses a Photodiode Array to accept the incoming light, a device that takes in light and redistributes it to a monitor for display by the user. Such a device is called a detector. The thickness of the crystal that the light travels through is determined by the crystal's position.If the crystal rests on a platform which is connected to an object whose position must always be monitored, then the crystal will move as the object moves. The different spectral signatures shown on a monitor reveal different thicknesses of the crystal, which reveal different positions of the monitored object. The object whose position is measured is the measurand.The selected crystal is quartz. It has a 12.5-mm length, a width of 10.8-mm at its thinnest end, and a taper angle to the thickest end of only 0.008 degrees, which corresponds to a 0.17-micron difference between the two. This angle is called the polishing angle of the quartz. The quartz itself is called the active cell. The Photodiode Array Detector receives the spectral signature from the optical fiber, and that signature is projected on an OSA, which is software built-in to the computer. A mathematical program is used to evaluate the signature, and the position of the measurand is thereby revealed. How accurate the measurement is can be revealed by use of a control device. If the quartz crystal is moved by a measuring device, such as a micrometer, the distance that the crystal moved may be measured by the micrometer, as well as by the OSA. By comparing the two, the accuracy of the spectrograph, and the position it reveals, can be known. / Department of Physics and Astronomy
45

Chemical sensing applications of fiber optics /

Nagarajan, Anjana, January 1994 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 77-79). Also available via the Internet.
46

High-speed and high-saturation-current partially depleted absorber photodetecters [i.e. photodetectors

Li, Xiaowei, Campbell, Joe, January 2004 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Joe C. Campbell. Vita. Includes bibliographical references.
47

Investigation of resonant-cavity-enhanced mercury cadmium telluride infrared detectors /

Wehner, Justin. January 2007 (has links)
Thesis (Ph.D)--University of Western Australia, 2007.
48

Sensor array optimization application of cluster analysis and genetic algorithms for sensor selection /

Sundar, Meghana. January 2007 (has links)
Thesis (M.S.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Systems Science and Industrial Engineering, 2007. / Includes bibliographical references.
49

Electrical measurements and UV-assisted gas detection of ZnO nanowires

Chan, Ka Cheung January 2014 (has links)
No description available.
50

The Use of Capacitive Transimpedance Amplifier Array Detectors for Mass Spectrometry

Zarzana, Christopher Andrew January 2011 (has links)
Mass spectrometry is a powerful tool in the field of analytical chemistry. Though there have been numerous advances in mass analyzer technology over the decades, there has been comparatively little advancement in mass spectrometer detector technology. The development of the scientific charged-coupled device over 30 years ago brought the advantages of simultaneous detection over single channel detection to optical spectroscopy, including higher signal-to-noise ratios for a fixed analysis time, shorter analysis time to obtain a given signal-to-noise ratio, and greater sample throughput. While the use of array detectors to achieve simultaneous detection is commonplace in optical spectroscopy, ion detectors for mass spectrometry have lagged behind.Over the last decade, a new type of ion detector, the capacitive transimpedance amplifier (CTIA) array detector, has been developed that has a number of properties that make it an excellent tool for simultaneous detection using dispersive mass spectrometers. The CTIA array detector has high sensitivity as well as high gain stability, allowing it to excel in applications that require high precision measurements of ion signals, such as isotope ratio mass spectrometry.Capacitive transimpedance amplifier array detectors have previously been used to demonstrate the power of simultaneous detection on Mattauch-Herzog double focusing mass spectrometers, but the non-linear mass dispersion of these instruments means that the resolution is not constant across the array. A different type of dispersive instrument, the linear cycloid, has a linear mass dispersion, making it a good candidate for an array detector.The first detailed characterization of gain, read noise and dark-current noise, as well as of operating behavior over a range of temperatures, of the DM0025, a 1696 pixel CTIA array detector was performed.In addition, the first-ever combination of a CTIA array detector with a linear cycloid mass spectrometer was developed. This combined instrument demonstrated simultaneous detection of multiple masses, as well as a linear mass range. The results from the detailed characterization of the detector were used in conjunction with measurements of the performance of the combined instrument to suggest improvements for the next generation of linear cycloid instruments with CTIA array detectors.

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