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INTERCONNECTION, INTERFACE AND INSTRUMENTATION FOR MICROMACHINED CHEMICAL SENSORS
Title
INTERCONNECTION, INTERFACE AND INSTRUMENTATION FOR MICROMACHINED CHEMICAL SENSORS.
Creator
Palsandram, Naveenkumar, Sundaram, Kalpathy, University of Central Florida
Abstract / Description
In realizing a portable chemical analysis system, adequate partitioning of a reusable component and a disposable is required. For successful implementation of micromachined sensors in an instrument, reliable methods for interconnection and interface are in great demand between these two major parts. This thesis work investigates interconnection methods of micromachined chip devices, a hybrid fluidic interface system, and measurement circuitry for completing instrumentation. The...
Show moreIn realizing a portable chemical analysis system, adequate partitioning of a reusable component and a disposable is required. For successful implementation of micromachined sensors in an instrument, reliable methods for interconnection and interface are in great demand between these two major parts. This thesis work investigates interconnection methods of micromachined chip devices, a hybrid fluidic interface system, and measurement circuitry for completing instrumentation. The interconnection method based on micromachining and injection molding techniques was developed and an interconnecting microfluidic package was designed, fabricated and tested. Alternatively, a plug-in type design for a large amount of sample flow was designed and demonstrated. For the hybrid interface, sequencing of the chemical analysis was examined and accordingly, syringe containers, a peristaltic pump and pinch valves were assembled to compose a reliable meso-scale fluidic control unit. A potentiostat circuit was modeled using a simulation tool. The simulated output showed its usability toward three-electrode electrochemical microsensors. Using separately fabricated microsensors, the final instrument with two different designs--flow-through and plug-in type was tested for chlorine detection in water samples. The chemical concentration of chlorine ions could be determined from linearly dependent current signals from the instrument.
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Date Issued
2005
Identifier
CFE0000673, ucf:46516
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0000673
CLASSICAL SIZE EFFECT IN CU THIN FILMS: IMPACT OF SURFACE AND GRAIN BOUNDARY SCATTERING ON RESISTIVITY
Title
CLASSICAL SIZE EFFECT IN CU THIN FILMS: IMPACT OF SURFACE AND GRAIN BOUNDARY SCATTERING ON RESISTIVITY.
Creator
Sun, Tik, Coffey, Kevin, University of Central Florida
Abstract / Description
Surface and grain boundary electron scattering contribute significantly to resistivity as the dimensions of polycrystalline metallic conductors are reduced to, and below, the electron mean free path. A quantitative measurement of the relative contributions of surface and grain boundary scattering to resistivity is very challenging, requiring not only the preparation of suitably small conductors having independent variation of the two relevant length scales, namely, the sample critical...
Show moreSurface and grain boundary electron scattering contribute significantly to resistivity as the dimensions of polycrystalline metallic conductors are reduced to, and below, the electron mean free path. A quantitative measurement of the relative contributions of surface and grain boundary scattering to resistivity is very challenging, requiring not only the preparation of suitably small conductors having independent variation of the two relevant length scales, namely, the sample critical dimension and the grain size, but also independent experimental quantification of these two length scales. In most work to date the sample grain size has been either assumed equal to conductor dimension or measured for only a small number of grains. Thus, the quantification of the classical size effect still suffers from an uncertainty in the relative contributions of surface and grain boundary scattering. In this work, a quantitative analysis of both surface and grain boundary scattering in Cu thin films with independent variation of film thickness (27 nm to 158 nm) and grain size (35 nm to 425 nm) in samples prepared by sub-ambient temperature film deposition followed by annealing is reported. Film resistivities of carefully characterized samples were measured at both room temperature and at 4.2 K and were compared with several scattering models that include the effects of surface and grain boundary scattering. Grain boundary scattering is found to provide the strongest contribution to the resistivity increase. However, a weaker, but significant, role is also observed for surface scattering. Several of the published models for grain boundary and surface scattering are explored and the Matthiessen's rule combination of the Mayadas and Shatzkes' model of grain boundary scattering and Fuchs and Sondheimer's model of surface scattering resistivity contributions is found to be most appropriate. It is found that the experimental data are best described by a grain boundary reflection coefficient of 0.43 and a surface specularity coefficient of 0.52. This analysis finds a significantly lower contribution from surface scattering than has been reported in previous works, which is in part due to the careful quantitative microstructural characterization of samples performed. The data does suggest that there is a roughness dependence to the surface scattering, but this was not conclusively demonstrated. Voids and impurities were found to have negligible impact on the measured resistivities of the carefully prepared films.
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Date Issued
2009
Identifier
CFE0002959, ucf:47949
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0002959
Fabrication and Characterization of Spatially-Variant Self-Collimating Photonic Crystals
Title
Fabrication and Characterization of Spatially-Variant Self-Collimating Photonic Crystals.
Creator
Digaum, Jennefir, Kuebler, Stephen, Kik, Pieter, Schoenfeld, Winston, Likamwa, Patrick, Gesquiere, Andre, University of Central Florida
Abstract / Description
Spatially-variant photonic crystals (SVPCs) created using materials having a low refractive index are shown to be capable of abruptly controlling light beams with high polarization selectivity. SVPCs are photonic crystals for which the orientation of the unit cell is controllably varied throughout the lattice to control the flow of light. Multi-photon lithography in a photo polymer was used to fabricate three-dimensional SVPCs that direct the flow of light around a 90 degree bend. The optical...
Show moreSpatially-variant photonic crystals (SVPCs) created using materials having a low refractive index are shown to be capable of abruptly controlling light beams with high polarization selectivity. SVPCs are photonic crystals for which the orientation of the unit cell is controllably varied throughout the lattice to control the flow of light. Multi-photon lithography in a photo polymer was used to fabricate three-dimensional SVPCs that direct the flow of light around a 90 degree bend. The optical performance of the SVPCs was characterized using a scanning optical-fiber system that introduced light onto the input face of a structure and measured the intensity of light emanating from the output faces.As a proof-of-concept, SVPCs that can bend a beam at a wavelength of ?0 = 2.94 ?m were fabricated in the photo-polymer SU-8. The SVPCs were shown to direct infrared light of one polarization through a sharp bend, while the other polarization propagated straight through the SVPC, when the volumetric fill-factor is near 50%. The peak-to-peak ratio of intensities of the bent- and straight-through beams was 8:1, and a power efficiency of 8% was achieved. The low efficiency is attributed to optical absorption in SU-8 at ?0 = 2.94 ?m.SVPCs that can bend a beam at telecommunications wavelengths near ?0 = 1.55 ?m were fabricated by multi-photon lithography in the photo-polymer IP-Dip. IP-Dip was chosen over SU 8 to enable fabrication of finer features, as are needed for an SVPC scaled in size to operate at shorter wavelengths. Experimental characterization shows that these particular SVPCs provide effective control of the vertically polarized beam at ?0 = 1.55 ?m, when the volumetric fill-factor is around 46%. The beam bending peak efficiency was found to be 52.5% with a peak-to-peak ratio between the bent- and straight-through beams of 78.7. Additionally, these SVPCs can bend a light beam with a broad bandwidth of 153 nm that encompasses both the C- and S-bands of the telecommunications window. Furthermore, the SVPCs have high tolerance to misalignment, in which an offset of the input beam by as much as 6 ?m causes the beam-bending efficiency to drop no more than 50%. Finally, it is shown that these particular SVPCs can bend beams without significantly distorting the mode profile. This work introduces a new scheme for controlling light that should be useful for integrated photonics.The penultimate chapter discusses nonlinear phenomena that were observed during the optical characterization of the SVPCs using a high peak-power amplified femtosecond laser system. The first of these effects is referred to as "super-collimation", in which the beam bending peak efficiency of certain SVPCs increases with input intensity, reaching as high as 68%. The second effect pertains to nonlinear imaging of light at ?0 = 1.55 ?m scattered from an SVPC and detected using a silicon-CCD camera. This effect enables beam bending within the device to be imaged in real time. The dissertation concludes with an outlook for SVPCs, discussing potential applications and challenges that must be addressed to advance their use in photonics.
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Date Issued
2016
Identifier
CFE0006527, ucf:51371
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006527
FINITE ELEMENT METHOD MODELING OF ADVANCED ELECTRONIC DEVICES
Title
FINITE ELEMENT METHOD MODELING OF ADVANCED ELECTRONIC DEVICES.
Creator
Chen, Yupeng, Wu, Thomas, University of Central Florida
Abstract / Description
In this dissertation, we use finite element method together with other numerical techniques to study advanced electron devices. We study the radiation properties in electron waveguide structure with multi-step discontinuities and soft wall lateral confinement. Radiation mechanism and conditions are examined by numerical simulation of dispersion relations and transport properties. The study of geometry variations shows its significant impact on the radiation intensity and direction. In...
Show moreIn this dissertation, we use finite element method together with other numerical techniques to study advanced electron devices. We study the radiation properties in electron waveguide structure with multi-step discontinuities and soft wall lateral confinement. Radiation mechanism and conditions are examined by numerical simulation of dispersion relations and transport properties. The study of geometry variations shows its significant impact on the radiation intensity and direction. In particular, the periodic corrugation structure exhibits strong directional radiation. This interesting feature may be useful to design a nano-scale transmitter, a communication device for future nano-scale system. Non-quasi-static effects in AC characteristics of carbon nanotube field-effect transistors are examined by solving a full time-dependent, open-boundary Schrödinger equation. The non-quasi-static characteristics, such as the finite channel charging time, and the dependence of small signal transconductance and gate capacitance on the frequency, are explored. The validity of the widely used quasi-static approximation is examined. The results show that the quasi-static approximation overestimates the transconductance and gate capacitance at high frequencies, but gives a more accurate value for the intrinsic cut-off frequency over a wide range of bias conditions. The influence of metal interconnect resistance on the performance of vertical and lateral power MOSFETs is studied. Vertical MOSFETs in a D2PAK and DirectFET package, and lateral MOSFETs in power IC and flip chip are investigated as the case studies. The impact of various layout patterns and material properties on RDS(on) will provide useful guidelines for practical vertical and lateral power MOSFETs design.
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Date Issued
2006
Identifier
CFE0001389, ucf:46987
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0001389
INVESTING IN AN INTERCONNECTED WORKFORCE:GLOBAL EDUCATION REFORM
Title
INVESTING IN AN INTERCONNECTED WORKFORCE:GLOBAL EDUCATION REFORM.
Creator
Klug, Amelia, Bryer, Thomas, University of Central Florida
Abstract / Description
Regardless of culture, socio-economic background, and quality of life, all students deserve the highest quality of education. But the reality is, many education systems around the world do not offer it. Investing in structural reforms in education has the potential to boost economic growth in countries around the world. By learning from different education systems strengths and weaknesses, policy decisions can be made that ensure students are given the opportunity for higher educational...
Show moreRegardless of culture, socio-economic background, and quality of life, all students deserve the highest quality of education. But the reality is, many education systems around the world do not offer it. Investing in structural reforms in education has the potential to boost economic growth in countries around the world. By learning from different education systems strengths and weaknesses, policy decisions can be made that ensure students are given the opportunity for higher educational outcomes. This study analyzes high, middle, and low quality education systems around the world and the infrastructures that lead to educational success or failure. Fifteen education systems are chosen for this study which includes Shanghai-China, Singapore, Japan, Finland, Canada, Portugal, United States, Luxembourg, Spain, Hungary, Brazil, Argentina, Indonesia, Qatar, and Peru. Each system is analyzed in terms of its teacher quality, curriculum, school system structure, and educational equity. From this study, it appears that there is a high-correlation between four indicators and top-educational success. These four indicators include having a highly selective model for hiring teachers, recruiting teachers from a top-pool of graduates, having a high-level of prestige held for teachers in society, and insuring students of low socio-economic status are given equal educational opportunities for success. Recommendations for a new teacher training and selection model are discussed based on the top four indicators. These recommendations could cause educational gains for both the United States and other systems around the world.
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Date Issued
2014
Identifier
CFH0004691, ucf:45247
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFH0004691