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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.
1

Silicon piezoresistors for MEMS pressure sensor applications

Tan, T. H. January 2014 (has links)
Silicon based micromachining technology enables the realization of high performance micro electromechanical systems (MEMS) including a range of physical and environmental sensors. Pressure sensors are used for a wide range of monitoring and control applications, e.g. environmental, industrial, aircraft, automotive. Monitoring of vehicle tyre pressures offers benefits such as improved safety, fuel economy, and tyre life. Micromachined pressure sensors are used at present, but require further research to improve their performance in terms of size, power consumption and manufacturing cost. This thesis has reviews pressure sensor technology and new developments in this area. A comparison of existing and potential future sensing mechanisms has been undertaken and identified as silicon piezoresistors. The focus of the research is motivated by the recently discovered enhanced piezoresistive effect in silicon nanowires where sensitivity can be increased by decreasing the dimension of nanowire. This thesis investigates the piezoresistive effect in p-type <110> silicon nanowires, fabricated using top down approach. It is found that the piezoresistive effect increases when the nanowire width is reduced below 400nm. Compared with micrometre sized piezoresistors, silicon nanowires have produced up to 100% enhancement. In addition, measurements indicate that the temperature coefficient of resistance (TCR) of silicon nanowire has improved with up to 40% decrease in TCR. The improvement in these two areas will be beneficial for the development of new MEMS pressure sensors. COMSOL is employed to simulate the piezoresistance effect in p-type <110> silicon for a range of doping concentrations. Simulation results demonstrate a similar trend to experimental results and publication data and show that the piezoresistance effect decreases as the doping concentration increases.
2

Zeolite modified metal oxides for gas sensing

Mann, Dominic Peter January 2005 (has links)
A novel method of improving the selectivity of metal oxide gas sensors has been developed by using catalytically active molecular sieve materials. They have been successfully introduced into a proprietary sensor array and a commercially available electronic nose. The cracking patterns of various organic compound groups including alkanes, aromatics and flavours over transition metal exchanged zeolites (ZSM-5, zeolite Y, and zeolite p) have been measured using a zeolite bed/GC/MS experimental set-up within a temperature range of 200 C to 400 C. The findings have been successfully translated for the use of the zeolites as filter technology on chromium titanium oxide (CTO) sensors for the purposes of selective gas sensing. Studies have been carried out regarding the effects of metal loading, zeolite type, material fabrication techniques and operating temperature with regards to catalytic activity and selectivity. Variations in activity due to alkane chain length have been related to the ability of the molecule to enter the zeolite cavity, the quantity of supported metal complexes and their oxidation state in the zeolite pores. The composite sensors utilising the novel zeolite materials have been used in a custom built sensor rig that houses 3 dual electrode sensors and can measure real time responses of these sensors to an introduced headspace generated from organic liquids. The response data have been utilised in a statistical software package (SPSS 12.0) to rationalise sensor discriminatory behaviour to various compound groups. The zeolite coated CTO sensors have also been tested in a commercial electronic nose array which has provided enhanced discrimination as compared to a standard CTO sensor array for a number of active and potential commercial applications mainly involving complex flavour compound mixtures.
3

Development and characterization of Si₃N₄-based composites for high-temperature sensor applications

Guo, Zhiquan January 2007 (has links)
No description available.
4

The development of an AC current transducer using printed circuit board techniques

Salisbury, Andrew Christopher January 2005 (has links)
No description available.
5

Novel intelligent gas-sensing in diagnosis of infectious diseases

Pavlou, Alexandros K. January 2002 (has links)
No description available.
6

Reactive ion etching techniques for uncooled pyroelectric detectors

Landi, S. January 2006 (has links)
No description available.
7

Chemical sensors based on fibre optics and fluorescence measurements

Campbell, Alexander January 2004 (has links)
No description available.
8

A new range of ultrasonic transducers

Trogé, Alexandre January 2007 (has links)
No description available.
9

Fibre laser development for sensor applications

Mandal, Jharna January 2005 (has links)
No description available.
10

An investigation into the use of mesoporous Pd films and silicon microfabricated microhotplates as a methane sensor

Dunford, Timothy Peter January 2006 (has links)
No description available.

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