+publisher:"Colorado State University" +contributor:("Lear, Kevin L.")

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Colorado State University

1. Thakkar, Ishan G. Plastic total internal reflection-based photoluminescence device for enzymatic biosensors, A.

Degree: MS(M.S.), Electrical and Computer Engineering, 2013, Colorado State University

URL: http://hdl.handle.net/10217/79210

► Growing concerns for quality of water, food and beverages in developing and developed countries drive sizeable markets for mass-producible, low cost devices that can measure… (more)

▼ Growing concerns for quality of water, food and beverages in developing and developed countries drive sizeable markets for mass-producible, low cost devices that can measure the concentration of contaminant chemicals in water, food, and beverages rapidly and accurately. Several fiber-optic enzymatic biosensors have been reported for these applications, but they exhibit very strong presence of scattered excitation light in the signal for sensing, requiring expensive thin-film filters, and their non-planar structure makes them challenging to mass-produce. Several other planar optical waveguide-based biosensors prove to be relatively costly and more fragile due to constituent materials and the techniques involved in their fabrication. So, a plastic total internal reflection (TIR)-based low cost, low scatter, field-portable device for enzymatic biosensors is fabricated and demonstrated. The design concept of the TIR-based photoluminescent enzymatic biosensor device is explained. An analysis of economical materials with appropriate optical and chemical properties is presented. PMMA and PDMS are found to be appropriate due to their high chemical resistance, low cost, high optical transmittance and low auto-fluorescence. The techniques and procedures used for device fabrication are discussed. The device incorporated a PMMA-based optical waveguide core and PDMS-based fluid cell with simple multi-mode fiber-optics using cost-effective fabrication techniques like molding and surface modification. Several techniques of robustly depositing photoluminescent dyes on PMMA core surface are discussed. A pH-sensitive fluorescent dye, fluoresceinamine, and an O2-sensitive phosphorescent dye, Ru(dpp) both are successfully deposited using Si-adhesive gel-based as well as HydroThane-based deposition methods. Two different types of pH-sensors using two different techniques of depositing fluoresceinamine are demonstrated. Also, the effect of concentration of fluoresceinamine-dye molecules on fluorescence intensity and scattered excitation light intensity is investigated. The fluorescence intensity to the scattered excitation light intensity ratio for dye deposition is found to increase with increase in concentration. However, both the absolute fluorescence intensity and absolute scatter intensity are found to decrease in different amounts with an increase in concentration. An enzymatic hydrogen peroxide (H2O2) sensor is made and demonstrated by depositing Ruthenium-based phosphorescent dye (Ru(dpp)3) and catalase-enzyme on the surface of the waveguide core. The O2-sensitive phosphorescence of Ru(dpp)3 is used as a transduction signal and the catalase-enzyme is used as a bio-component for sensing. The H2O2 sensor exhibits a phosphorescence signal to scattered excitation light ratio of 100±18 without filtering. The unfiltered device demonstrates a detection limit of (2.20±0.6) µM with the linear range from 200µM to 20mM. An enzymatic lactose sensor is designed and characterized using Si-adhesive gel based Ru(dpp)3 deposition and oxidase… Advisors/Committee Members: Lear, Kevin L. (advisor), Reardon, Kenneth (committee member), Collins, George (committee member).

Subjects/Keywords: total internal reflection fluorescence (TIRF); indicator dye; total internal reflection; photoluminescence; enzymatic; evanescent field

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APA (6^th Edition):

Thakkar, I. G. (2013). Plastic total internal reflection-based photoluminescence device for enzymatic biosensors, A. (Masters Thesis). Colorado State University. Retrieved from http://hdl.handle.net/10217/79210

Chicago Manual of Style (16^th Edition):

Thakkar, Ishan G. “Plastic total internal reflection-based photoluminescence device for enzymatic biosensors, A.” 2013. Masters Thesis, Colorado State University. Accessed April 13, 2021. http://hdl.handle.net/10217/79210.

MLA Handbook (7^th Edition):

Thakkar, Ishan G. “Plastic total internal reflection-based photoluminescence device for enzymatic biosensors, A.” 2013. Web. 13 Apr 2021.

Vancouver:

Thakkar IG. Plastic total internal reflection-based photoluminescence device for enzymatic biosensors, A. [Internet] [Masters thesis]. Colorado State University; 2013. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/10217/79210.

Council of Science Editors:

Thakkar IG. Plastic total internal reflection-based photoluminescence device for enzymatic biosensors, A. [Masters Thesis]. Colorado State University; 2013. Available from: http://hdl.handle.net/10217/79210

Colorado State University

2. Kindt, Joel D. Optofluidic intracavity spectroscopy for spatially, temperature, and wavelength dependent refractometry.

Degree: MS(M.S.), Electrical and Computer Engineering, 2012, Colorado State University

URL: http://hdl.handle.net/10217/68122

► A microfluidic refractometer was designed based on previous optofluidic intracavity spectroscopy (OFIS) chips utilized to distinguish healthy and cancerous cells. The optofluidic cavity is realized… (more)

▼ A microfluidic refractometer was designed based on previous optofluidic intracavity spectroscopy (OFIS) chips utilized to distinguish healthy and cancerous cells. The optofluidic cavity is realized by adding high reflectivity dielectric mirrors to the top and bottom of a microfluidic channel. This creates a plane-plane Fabry-Perot optical cavity in which the resonant wavelengths are highly dependent on the optical path length inside the cavity. Refractometry is a useful method to determine the nature of fluids, including the concentration of a solute in a solvent as well as the temperature of the fluid. Advantages of microfluidic systems are the easy integration with lab-on-chip devices and the need for only small volumes of fluid. The unique abilities of the microfluidic refractometer in this thesis include its spatial, temperature, and wavelength dependence. Spatial dependence of the transmission spectrum is inherent through a spatial filtering process implemented with an optical fiber and microscope objective. A sequence of experimental observations guided the change from using the OFIS chip as a cell discrimination device to a complimentary refractometer. First, it was noted the electrode structure within the microfluidic channel, designed to trap and manipulate biological cells with dielectrophoretic (DEP) forces, caused the resonant wavelengths to blue-shift when the electrodes were energized. This phenomenon is consistent with the negative dn/dT property of water and water-based solutions. Next, it was necessary to develop a method to separate the optical path length into physical path length and refractive index. Air holes were placed near the microfluidic channel to exclusively measure the cavity length with the known refractive index of air. The cavity length was then interpolated across the microfluidic channel, allowing any mechanical changes to be taken into account. After the separation of physical path length and refractive index, it was of interest to characterize the temperature dependent refractive index relationship, n(T), for phosphate buffered saline. Phosphate buffered saline(PBS) is a water-based solution used with our biological cells because it maintains an ion concentration similar to that found in body fluids. The n(T) characterization was performed using a custom-built isothermal apparatus in which the temperature could be controlled. To check for the accuracy of the PBS refractive index measurements, water was also measured and compared with known values in the literature. The literature source of choice has affiliations to NIST and a formulation of refractive index involving temperature and wavelength dependence, two parameters which are necessary for our specialized infrared wavelength range. From the NIST formula, linear approximations were found to be dn/dT = -1.4×10-4 RIU °C-1 and dn/dλ = -1.5×10-5 RIU nm-1 for water. A comparison with the formulated refractive indices of water indicated the measured values were off. This was attributed to the fact that light… Advisors/Committee Members: Lear, Kevin L. (advisor), Buchanan, Kristen (committee member), Notaros, Branislav (committee member).

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APA (6^th Edition):

Kindt, J. D. (2012). Optofluidic intracavity spectroscopy for spatially, temperature, and wavelength dependent refractometry. (Masters Thesis). Colorado State University. Retrieved from http://hdl.handle.net/10217/68122

Chicago Manual of Style (16^th Edition):

Kindt, Joel D. “Optofluidic intracavity spectroscopy for spatially, temperature, and wavelength dependent refractometry.” 2012. Masters Thesis, Colorado State University. Accessed April 13, 2021. http://hdl.handle.net/10217/68122.

MLA Handbook (7^th Edition):

Kindt, Joel D. “Optofluidic intracavity spectroscopy for spatially, temperature, and wavelength dependent refractometry.” 2012. Web. 13 Apr 2021.

Vancouver:

Kindt JD. Optofluidic intracavity spectroscopy for spatially, temperature, and wavelength dependent refractometry. [Internet] [Masters thesis]. Colorado State University; 2012. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/10217/68122.

Council of Science Editors:

Kindt JD. Optofluidic intracavity spectroscopy for spatially, temperature, and wavelength dependent refractometry. [Masters Thesis]. Colorado State University; 2012. Available from: http://hdl.handle.net/10217/68122

Colorado State University

3. Yi, Zhangjing. Characterization of a photoluminescence-based fiber optic sensor system.

Degree: MS(M.S.), Electrical and Computer Engineering, 2011, Colorado State University

URL: http://hdl.handle.net/10217/70840

► Measuring multiple analyte concentrations is essential for a wide range of environmental applications, which are important for the pursuit of public safety and health. Target… (more)

▼ Measuring multiple analyte concentrations is essential for a wide range of environmental applications, which are important for the pursuit of public safety and health. Target analytes are often toxic chemical compounds found in groundwater or soil. However, in-situ measurement of such analytes still faces various challenges. Some of these challenges are rapid response for near-real time monitoring, simultaneous measurements of multiple analytes in a complex target environment, and high sensitivity for low analyte concentration without sample pretreatment. This thesis presents a low-cost, robust, multichannel fiber optic photoluminescence (PL)-based sensor system using a time-division multiplexing architecture for multiplex biosensor arrays for in-situ measurements in environmental applications. The system was designed based upon an indirect sensing scheme with a pH or oxygen sensitive dye molecules working as the transducer that is easily adaptable with various enzymes for detecting different analytes. A characterization of the multi-channel fiber optic PL-based sensor system was carried out in this thesis. Experiments were designed with interests in investigating this system's performance with only the transducer thus providing reference figures of merit, such as sensitivity and limit of detection, for further experiments or applications with the addition of various biosensors. A pH sensitive dye, fluoresceinamine (FLA), used as the transducer is immobilized in a poly vinyl alcohol (PVA) matrix for the characterization. The system exhibits a sensitivity of 8.66×10 5 M -1 as the Stern-Volmer constant, K SV , in H + concentration measurement range of 0.002 - 891 μM (pH of 3.05 - 8.69). A mathematical model is introduced to describe the Stern-Volmer equation's non-idealities, which are fluorophore fractional accessibility and the back reflection. Channel-to-channel uniformity is characterized with the modified Stern-Volmer model. Combining the FLA with appropriate enzymatic biosensors, the system is capable of 1,2-dichloroethane (DCA) and ethylene dibromide (EDB) detection. The calculated limit of detection (LOD) of the system can be as low as 0.08 μg/L for DCA and 0.14 μg/L for EDB. The performances of fused fiber coupler and bifurcated fiber assembly were investigated for the application in the fiber optic PL-based sensor systems in this thesis. Complex tradeoffs among back reflection noise, coupling efficiency and split ratio were analyzed with theoretical and experimental data. A series of experiments and simulations were carried out to compare the two types of fiber assemblies in the PL-based sensor systems in terms of excess loss, split ratio, back reflection, and coupling efficiency. A noise source analysis of three existing PL-intensity-based fiber optic enzymatic biosensor systems is provided to reveal the power distribution of different noise components. The three systems are a single channel system with a spectrometer as the detection device, a lab-developed multi-channel system, and a commercial prototype… Advisors/Committee Members: Lear, Kevin L. (advisor), Pezeshki, Ali (committee member), Mueller, Jennifer L. (committee member).

Subjects/Keywords: biosensor; Stern-Volmer; photoluminescence; fiber optic; enzyme

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Yi, Z. (2011). Characterization of a photoluminescence-based fiber optic sensor system. (Masters Thesis). Colorado State University. Retrieved from http://hdl.handle.net/10217/70840

Chicago Manual of Style (16^th Edition):

Yi, Zhangjing. “Characterization of a photoluminescence-based fiber optic sensor system.” 2011. Masters Thesis, Colorado State University. Accessed April 13, 2021. http://hdl.handle.net/10217/70840.

MLA Handbook (7^th Edition):

Yi, Zhangjing. “Characterization of a photoluminescence-based fiber optic sensor system.” 2011. Web. 13 Apr 2021.

Vancouver:

Yi Z. Characterization of a photoluminescence-based fiber optic sensor system. [Internet] [Masters thesis]. Colorado State University; 2011. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/10217/70840.

Council of Science Editors:

Yi Z. Characterization of a photoluminescence-based fiber optic sensor system. [Masters Thesis]. Colorado State University; 2011. Available from: http://hdl.handle.net/10217/70840

Colorado State University

4. Obeidat, Yusra Mahmoud. Modeling of optical waveguides with porous silica claddings and their use in LEAC sensors.

Degree: MS(M.S.), Electrical and Computer Engineering, 2014, Colorado State University

URL: http://hdl.handle.net/10217/88585

► Integrated optical biosensors have many advantages such as low-cost, portability and the ability to detect multiple analytes on a single waveguide. They can be used… (more)

▼ Integrated optical biosensors have many advantages such as low-cost, portability and the ability to detect multiple analytes on a single waveguide. They can be used in many important applications including biosensing applications. Previous research work focused on the issues of design, modeling and measurement of the local evanescent array coupled (LEAC) biosensor. The sensors were made using conventional dielectrics such as SiO2 and SiNx. The large increase in the complexity of the integrated circuits has increased the need for developing low-k dielectrics as new materials to cope with the integration challenges and improve operating speed. Furthermore, optical interconnects are required to be used to replace electrical interconnects in ICs to meet future goals. This increases the need for simultaneous manufacturing of electronics and optics on the same chip using a CMOS process. The research conducted during my Master of Science studies has addressed two important goals. The first was to use models to calculate surface and volume scattering losses in optical waveguides, especially, ones with porous silica claddings. The second goal was to use the simulation results to demonstrate the possibility of using porous silica in designing optical waveguides and LEAC sensors. By applying these models to porous silica optical waveguides described in previous publications, the agreement between their experimental results and the models results have been proved. Thus, these models can be used in the future to calculate the scattering losses in optical waveguides including ones with porous silica cladding. The main methods that are used to prepare porous silica and the models that are used to determine the effective index of porous silica have been discussed. A Matlab modesolver was used to simulate porous silica waveguides. Predictions for sensor sensitivity and waveguide loss as a function of waveguide dimension have been made using modesolver simulation results. The results demonstrate the ability to use porous silica in LEAC sensors in the future. Advisors/Committee Members: Lear, Kevin L. (advisor), Pasricha, Sudeep (committee member), Pinaud, Olivier (committee member).

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Obeidat, Y. M. (2014). Modeling of optical waveguides with porous silica claddings and their use in LEAC sensors. (Masters Thesis). Colorado State University. Retrieved from http://hdl.handle.net/10217/88585

Chicago Manual of Style (16^th Edition):

Obeidat, Yusra Mahmoud. “Modeling of optical waveguides with porous silica claddings and their use in LEAC sensors.” 2014. Masters Thesis, Colorado State University. Accessed April 13, 2021. http://hdl.handle.net/10217/88585.

MLA Handbook (7^th Edition):

Obeidat, Yusra Mahmoud. “Modeling of optical waveguides with porous silica claddings and their use in LEAC sensors.” 2014. Web. 13 Apr 2021.

Vancouver:

Obeidat YM. Modeling of optical waveguides with porous silica claddings and their use in LEAC sensors. [Internet] [Masters thesis]. Colorado State University; 2014. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/10217/88585.

Council of Science Editors:

Obeidat YM. Modeling of optical waveguides with porous silica claddings and their use in LEAC sensors. [Masters Thesis]. Colorado State University; 2014. Available from: http://hdl.handle.net/10217/88585

Colorado State University

5. Erickson, Timothy. Design, optimziation and fabrication of an integrated optoelectronic sensing chip with applications in groundwater contaminant detection and biosensing.

Degree: PhD, Electrical and Computer Engineering, 2014, Colorado State University

URL: http://hdl.handle.net/10217/83734

► The LEAC (Local Evanescent Array Coupled) chip is a CMOS-compatible, waveguide-based, label-free, optoelectronic sensor, which can function as a biosensor or environmental sensor. Unique among… (more)

▼ The LEAC (Local Evanescent Array Coupled) chip is a CMOS-compatible, waveguide-based, label-free, optoelectronic sensor, which can function as a biosensor or environmental sensor. Unique among optoelectronic sensors, the ~1 cm2 LEAC chip features an integrated photodetector array, which increases device portability, enables multi-analyte detection on a single waveguide, and simplifies system instrumentation. At its core, the LEAC chip is simply a precision refractometer, which can sense very small changes in refractive index (~5x10-6) in its multiple upper cladding sensing regions. The chip can be functionalized for detection of biomarkers or groundwater contaminants, which bind or diffuse into the waveguide's upper cladding sensing region, thereby producing a measurable change in refractive index. The research conducted during my doctoral studies has addressed two important goals. The first was to optimize the chip's sensing performance. The second goal was to run proof of concept experiments, in order to demonstrate its utility in practical sensing applications. By incorporating multiple engineering improvements, the sensing performance of the LEAC chip has been improved to the point where it may be competitive with low-end surface plasmon resonance (SPR) systems for bulk refractive index sensing. We have demonstrated the LEAC sensing platform for both environmental and biosensing applications. These include sensing aromatic hydrocarbons such as benzene, toluene and xylenes in groundwater at sub-ppm concentrations and detection of the cardiac infarction biomarker TroponinI. Research results have been communicated in peer-reviewed journals and presented at conferences, as summarized in Appendix J. Additionally, the intellectual property that was developed during the course of research activities has served as the basis for several patent filings. This dissertation provides a comprehensive account of research conducted on the LEAC sensing platform, while working as a graduate student in Dr. Kevin Lear's laboratory. It is structured in the following manner. In Chapter 1, the basic functionality of LEAC chip is introduced, while providing the necessary background to motivate its development. Chapter 2 provides a comprehensive and comparative overview of other label-free biosensors and groundwater aromatic hydrocarbon contaminant sensors. It reviews the requirements of other sensing systems and demonstrates the uniquely portable aspects of LEAC chip technology. It is provided for completeness, in order to summarize the state-of-the-art in the field of portable sensing and highlight some of the unique advantages of the LEAC sensor. In Chapter 3, the engineering aspects of performance optimization over prior art are described in detail. Whereas the 1st generation LEAC chip was fabricated at Avago Technologies, all 2nd generation LEAC chips have been fabricated by myself in the CSU cleanroom or at the Colorado Nanofabrication Lab in Boulder. The development of 2nd generation LEAC chips, including device physics,… Advisors/Committee Members: Lear, Kevin L. (advisor), Roberts, Jacob (committee member), Notaros, Branislav (committee member), Collins, George (committee member).

Subjects/Keywords: biosensor; groundwater sensor; integrated photodetector; optical waveguide; BTEX; environmental contaminant sensor

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APA (6^th Edition):

Erickson, T. (2014). Design, optimziation and fabrication of an integrated optoelectronic sensing chip with applications in groundwater contaminant detection and biosensing. (Doctoral Dissertation). Colorado State University. Retrieved from http://hdl.handle.net/10217/83734

Chicago Manual of Style (16^th Edition):

Erickson, Timothy. “Design, optimziation and fabrication of an integrated optoelectronic sensing chip with applications in groundwater contaminant detection and biosensing.” 2014. Doctoral Dissertation, Colorado State University. Accessed April 13, 2021. http://hdl.handle.net/10217/83734.

MLA Handbook (7^th Edition):

Vancouver:

Erickson T. Design, optimziation and fabrication of an integrated optoelectronic sensing chip with applications in groundwater contaminant detection and biosensing. [Internet] [Doctoral dissertation]. Colorado State University; 2014. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/10217/83734.

Council of Science Editors:

Erickson T. Design, optimziation and fabrication of an integrated optoelectronic sensing chip with applications in groundwater contaminant detection and biosensing. [Doctoral Dissertation]. Colorado State University; 2014. Available from: http://hdl.handle.net/10217/83734

Colorado State University

6. Koepke, Marina M. Optical detection methods for microfluidic devices.

Degree: MS(M.S.), Electrical and Computer Engineering, 2020, Colorado State University

URL: http://hdl.handle.net/10217/212075

► Optical technology is a common tool integrated onto microfluidic devices to aid in data collection and counting for biological and chemical research. In this study,… (more)

▼ Optical technology is a common tool integrated onto microfluidic devices to aid in data collection and counting for biological and chemical research. In this study, a simple optical technique was investigated as a detection method for microfluidic impedance cytometry (MIC) devices. The MIC devices were designed to characterize size and structure of parasite eggs through electrical impedance measurements. This data could directly benefit the medical and veterinary communities by providing information to aid in addressing helminth infections in humans and animals. The current MIC device and instrumentation does not provide a robust way to validate which impedance changes correlate to parasite eggs passing through the electrodes. To address this, an optical detection method was designed, implemented and tested on two different types of microfluidic devices: a glass device and printed circuit board (PCB) device. The optical hardware was accompanied by a trigger circuit that was used to process and manipulate the detected light signal. The circuit was designed with a sensitivity that would detect small changes in light from strongyle-type eggs flowing through the microfluidic channel. The trigger circuit was composed of multiple stages of signal amplification and oscillation suppression techniques so the changes in light could clearly be detected by the electronics. This method proved to be successful in detecting voltage changes ranging from 1.7 mV to 6.8 mV which resulted from strongyle egg sized particles (63-75 μm in diameter) flowing through the microfluidic channel. Adaptations for the optics, bench set-up and microfluidic device design were investigated to transfer this method to different laboratory settings. This study outlines the process of utilizing basic lab tools and components to create an easy to implement optical detection method for a variety of chip designs and laboratory set-ups. Advisors/Committee Members: Lear, Kevin L. (advisor), Wilson, Jesse (committee member), Gustafson, Daniel (committee member).

Subjects/Keywords: optical detection; trigger circuit; parasite detection; microfluidics

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Koepke, M. M. (2020). Optical detection methods for microfluidic devices. (Masters Thesis). Colorado State University. Retrieved from http://hdl.handle.net/10217/212075

Chicago Manual of Style (16^th Edition):

Koepke, Marina M. “Optical detection methods for microfluidic devices.” 2020. Masters Thesis, Colorado State University. Accessed April 13, 2021. http://hdl.handle.net/10217/212075.

MLA Handbook (7^th Edition):

Koepke, Marina M. “Optical detection methods for microfluidic devices.” 2020. Web. 13 Apr 2021.

Vancouver:

Koepke MM. Optical detection methods for microfluidic devices. [Internet] [Masters thesis]. Colorado State University; 2020. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/10217/212075.

Council of Science Editors:

Koepke MM. Optical detection methods for microfluidic devices. [Masters Thesis]. Colorado State University; 2020. Available from: http://hdl.handle.net/10217/212075

Colorado State University

7. Yan, Rongjin. CMOS compatible optical biosensing system based on local evanescent field shift mechanism, A.

Degree: PhD, Electrical and Computer Engineering, 2011, Colorado State University

URL: http://hdl.handle.net/10217/70407

► The need for label-free integrated optical biosensors has dramatically increased in recent years. Integrated optical biosensors have many advantages, including low-cost, and portability. They can… (more)

▼ The need for label-free integrated optical biosensors has dramatically increased in recent years. Integrated optical biosensors have many advantages, including low-cost, and portability. They can be applied to many fields, including clinical diagnostics, food safety, environmental monitoring, and biosecurity applications. One of the most important applications is point-of-care diagnosis, which means the disease could be tested at or near the site of patient care rather than in a laboratory. We are exploring the issues of design, modeling and measurement of a novel chip-scale local evanescent array coupled (LEAC) biosensor, which is an ideal platform for point-of-care diagnosis. Until now, three generations of LEAC samples have been designed, fabricated and tested. The 1st generation of LEAC sensor without a buried detector array was characterized using a commercial near field scanning optical microscope (NSOM). The sample was polished and was end-fire light coupled using single mode fiber. The field shift mechanism in this proof-to-concept configuration without buried detector arrays has been validated with inorganic adlayers [1], photoresist [2] and different concentrations of CRP proteins [3]. Mode beating phenomena was predicted by the beam propagation method (BPM) and was observed in the NSOM measurement. A 2nd generation LEAC sensor with a buried detector array was fabricated using 0.35μm CMOS process at the Avogo Technologies Inc., Fort Collins, Colorado. Characterizations with both single layer patternings, including photoresist as well as BSA [4] and immunoassay complexes [5] were done with cooperative efforts from various research groups. The BPM method was used to study the LEAC sensor, and the simulation results demonstrated the sensitivity of the LEAC sensor is 16%/nm, which was proved to match well with the experimental data [6]. Different antigen/antibodies, including mouse IgG and Hspx (a tuberculosis reactive antigen), have been used to test the immunoassay ability of LEAC sensor [7]. Many useful data have been collected by using the 2nd generation LEAC chip. However, during the characterization of the Avago chips, some design problems were revealed, including incompatibility with microfluidic integration, restricted detection region, strong sidewall scattering and uncoupled light interference from the single mode fiber. To address these problems, the 3rd generation LEAC sensor chip with buried detector arrays was designed to allow real-time monitoring and compatibility with microfluidic channel integration. 3rd generation samples have been fabricated in the CSU cleanroom and the mesa detector structure has been replaced with the thin insulator detector structure to solve the problems encountered during the characterizations. PDMS microfluidic channels and a multichannel measurement system consisting of a probe card, a multiplexing/amplification circuit and a LabVIEW program have been implemented into the LEAC system. In recent years, outbreaks of fast spreading viral diseases, such as… Advisors/Committee Members: Lear, Kevin L. (advisor), Dandy, David S. (committee member), Chandrasekar, V. (committee member), Notaros, Branislav (committee member).

Subjects/Keywords: biosensor; evanescent field; immunoassay; tuberculosis; virus; waveguide

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Yan, R. (2011). CMOS compatible optical biosensing system based on local evanescent field shift mechanism, A. (Doctoral Dissertation). Colorado State University. Retrieved from http://hdl.handle.net/10217/70407

Chicago Manual of Style (16^th Edition):

Yan, Rongjin. “CMOS compatible optical biosensing system based on local evanescent field shift mechanism, A.” 2011. Doctoral Dissertation, Colorado State University. Accessed April 13, 2021. http://hdl.handle.net/10217/70407.

MLA Handbook (7^th Edition):

Yan, Rongjin. “CMOS compatible optical biosensing system based on local evanescent field shift mechanism, A.” 2011. Web. 13 Apr 2021.

Vancouver:

Yan R. CMOS compatible optical biosensing system based on local evanescent field shift mechanism, A. [Internet] [Doctoral dissertation]. Colorado State University; 2011. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/10217/70407.

Council of Science Editors:

Yan R. CMOS compatible optical biosensing system based on local evanescent field shift mechanism, A. [Doctoral Dissertation]. Colorado State University; 2011. Available from: http://hdl.handle.net/10217/70407

Colorado State University

8. Safaisini, Rashid. Impact of thermal management on vertical-cavity surface-emitting laser (VCSEL) power and speed.

Degree: PhD, Electrical and Computer Engineering, 2011, Colorado State University

URL: http://hdl.handle.net/10217/52126

► Increasing the modulation bandwidth and output power of vertical-cavity surface-emitting lasers (VCSELs) are of great importance in a variety of applications such as data communication… (more)

▼ Increasing the modulation bandwidth and output power of vertical-cavity surface-emitting lasers (VCSELs) are of great importance in a variety of applications such as data communication systems. The high temperature generated in the active region of VCSELs is one of the main limiting factors in achieving high power and high speed operation. This work is focused on investigating the effects of thermal management on improving AC and DC properties of VCSELs and achieving higher thermal performance devices. Thermal heatsinking is obtained by surrounding the VCSEL mesas with high thermal conductivity materials such as copper and also using passive heatsinking by flip-chip bonding the laser dies on a GaAs heat spreader. The research includes fabricating and characterizing 980 nm bottom-emitting and 670 nm top-emitting oxide-confined VCSELs. This dissertation is divided into three main parts: high-power, high-speed 980 nm VCSEL arrays, low thermal resistance 670 nm VCSELs, and temperature dependent dynamics of 980 nm VCSELs. Experimental work performed on fabricating and characterizing 980 nm, bottom-emitting, oxide-confined VCSEL arrays and single elements is presented first. The result of DC and AC characterization confirms the effectiveness of Cu electroplating of mesas and flip-chip bonding in reducing VCSELs' thermal resistance to obtain lower operating temperatures. Uniformity of frequency response and operating wavelength across the arrays also motivates managing thermal issues and is an indication of uniform distribution of current and heat flux on the array. This research resulted in record VCSEL arrays with frequency response of approximately 8 GHz and operating CW power of 200 mW. These 28-element, 18µm aperture diameter arrays represent the highest power reported for a VCSEL or VCSEL array with greater than 1 GHz modulation bandwidth. The second part of this dissertation details the fabrication steps and DC characterization of visible, 670 nm, top-emitting, oxide-confined VCSELs. Since achieving high operating temperatures is one of the main challenges in realizing improved red VCSELs, the effect of mesa heatsinking on improving their DC behavior using copper electroplating of mesas is studied. Thermal modeling of the copper plated VCSELs also facilitates better understanding and analysis of the experimental results. A photomask and process flow were designed to fabricate VCSELs with a variety of mesa diameters and inner and outer plating sizes to investigate the major direction of heat flow in the VCSELs and decrease VCSEL thermal resistance and thus increase the output power. Although copper plating significantly reduces thermal resistance, it did not substantially increase maximum operating temperature of the red devices and also put the mesas under stress that might not be desired. This study led us to analyzing the effects of stress on the VCSEL mesas which is induced by the copper films. Finally, the temperature dependence of 980 nm VCSEL dynamics is investigated using noise spectra measurement. This… Advisors/Committee Members: Lear, Kevin L. (advisor), Marconi, Mario C. (committee member), Reising, Steven C. (committee member), Sites, James R. (committee member).

Subjects/Keywords: high power VCSELs; semiconductor laser; high speed VCSELs

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Safaisini, R. (2011). Impact of thermal management on vertical-cavity surface-emitting laser (VCSEL) power and speed. (Doctoral Dissertation). Colorado State University. Retrieved from http://hdl.handle.net/10217/52126

Chicago Manual of Style (16^th Edition):

Safaisini, Rashid. “Impact of thermal management on vertical-cavity surface-emitting laser (VCSEL) power and speed.” 2011. Doctoral Dissertation, Colorado State University. Accessed April 13, 2021. http://hdl.handle.net/10217/52126.

MLA Handbook (7^th Edition):

Safaisini, Rashid. “Impact of thermal management on vertical-cavity surface-emitting laser (VCSEL) power and speed.” 2011. Web. 13 Apr 2021.

Vancouver:

Safaisini R. Impact of thermal management on vertical-cavity surface-emitting laser (VCSEL) power and speed. [Internet] [Doctoral dissertation]. Colorado State University; 2011. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/10217/52126.

Council of Science Editors:

Safaisini R. Impact of thermal management on vertical-cavity surface-emitting laser (VCSEL) power and speed. [Doctoral Dissertation]. Colorado State University; 2011. Available from: http://hdl.handle.net/10217/52126

Colorado State University

9. Koishiyev, Galymzhan Temirkhanovich. Analysis of impact of non-uniformities on thin-film solar cells and modules with 2-D simulations.

Degree: PhD, Physics, 2010, Colorado State University

URL: http://hdl.handle.net/10217/39060

► Clean and environmentally friendly photovoltaic (PV) technologies are now generally recognized as an alternative solution to many global-scale problems such as energy demand, pollution, and… (more)

▼ Clean and environmentally friendly photovoltaic (PV) technologies are now generally recognized as an alternative solution to many global-scale problems such as energy demand, pollution, and environment safety. The cost ($/kWh) is the primary challenge for all PV technologies. In that respect, thin-film polycrystalline PV technology (CdTe, Cu(In,Ga)Se2, etc), due to its fast production line, large area panels and low material usage, is one of the most promising low-cost technologies. Due to their granular structure, thin-film solar cells are inherently non-uniform. Also, inevitable fluctuations during the multistep deposition process of large area thin-film solar panels and specific manufacturing procedures such as scribing result in non-uniformities. Furthermore, non-uniformities can occur, become more severe, or increase in size during the solar-panel's life cycle due to various environmental conditions (i.e. temperature variation, shading, hail impact, etc). Non-uniformities generally reduce the overall efficiency of solar cells and modules, and their effects therefore need to be well understood. This thesis focuses on the analysis of the effect of non-uniformities on small size solar cells and modules with the help of numerical simulations. Even though the 2-D model developed here can analyze the effect of non-uniformities of any nature, only two specific types of microscopic non-uniformities were addressed here: shunts and weak-diodes. One type of macroscopic non-uniformity, partial shading, was also addressed. The circuit model developed here is a network of diodes, current-sources, and transparent-conductive-oxide (TCO) resistors. An analytic relation between the TCO-resistor, which is the primary model parameter, and TCO sheet resistance ρS, which is the corresponding physical parameter, was derived. Based on the model several useful general results regarding a uniform cell were deduced. In particular, a global parameter δ which determines the performance of a uniform solar cell depending on sheet resistance ρS, cell length L, and other basic parameters, was found. The expression for the lumped series resistance in terms of physical parameters was also derived. Primary power loss mechanisms in the uniform case and their dependence on ρS, L, and light generated current JL were determined. Similarly, power losses in a small-area solar cell with either a shunt or a weak-microdiode were identified and their dependence on ρS, JL, and location of the non-uniformity with respect to the current collecting contact was studied. The impact of multiple identical non-uniformities (shunts or weak-diodes) on the performance of a module was analyzed and estimates of efficiency loss were presented. It was found that the efficiency of the module strongly depends not only on the severity and fractional area of non-uniformities but also on their distribution pattern. A numerical parameter characterizing distribution pattern of non-uniformities was introduced. The most and least favorable distribution patterns of shunts and… Advisors/Committee Members: Sites, James R. (advisor), Lear, Kevin L. (committee member), Leisure, Robert Glenn, 1938- (committee member), Harton, John L. (committee member).

Subjects/Keywords: weak-diode; thin-film; solar cells; shunt; sheet resistance; 2D model; Solar cells; Thin films; Photovoltaic cells; Electroluminescence

Record Details Similar Records Cite « Share

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Koishiyev, G. T. (2010). Analysis of impact of non-uniformities on thin-film solar cells and modules with 2-D simulations. (Doctoral Dissertation). Colorado State University. Retrieved from http://hdl.handle.net/10217/39060

Chicago Manual of Style (16^th Edition):

Koishiyev, Galymzhan Temirkhanovich. “Analysis of impact of non-uniformities on thin-film solar cells and modules with 2-D simulations.” 2010. Doctoral Dissertation, Colorado State University. Accessed April 13, 2021. http://hdl.handle.net/10217/39060.

MLA Handbook (7^th Edition):

Koishiyev, Galymzhan Temirkhanovich. “Analysis of impact of non-uniformities on thin-film solar cells and modules with 2-D simulations.” 2010. Web. 13 Apr 2021.

Vancouver:

Koishiyev GT. Analysis of impact of non-uniformities on thin-film solar cells and modules with 2-D simulations. [Internet] [Doctoral dissertation]. Colorado State University; 2010. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/10217/39060.

Council of Science Editors:

Koishiyev GT. Analysis of impact of non-uniformities on thin-film solar cells and modules with 2-D simulations. [Doctoral Dissertation]. Colorado State University; 2010. Available from: http://hdl.handle.net/10217/39060

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