University of Twente Student Theses


Optimizing the detection limit of micro ring resonators

Mustafa, Hasib (2014) Optimizing the detection limit of micro ring resonators.

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Abstract:The application of Microring Resonators (MRRs) for lab-on-a-chip and environmental detection is an emerging trend in the chemical industry. Advances in technology enable low-cost, high- throughput, cost- and time-saving benefits; thus, the commercial factors of a certain technology rely on early development work. In the recent years, the feasibility of MRRs for biochemical sensing has been realized. However, it is recommended in the majority of the literature that the minimization of the influence of external factors should be given priority for an increased accuracy of the detection system. Since real time diagnostics requires a real time efficient signal processing of the measured data, statistical signal processing can provide robust, efficient and fast computation over the noisy data with significantly accurate and precise results. This thesis covers the design and implementation of a detection system aimed to provide high accuracy and precision in detecting the resonance peak wavelength of the MRR. The de- signed curve-fitting algorithm is implemented within the detection software as a subprogram called peak detection. This incorporates most of the mathematical computations required for determining the resonance peak position. The peak detection is designed by means of nonlin- ear least squares minimization along with dynamic free spectral range calculation, which is proposed in this thesis. Measurement instruments are calibrated for detecting the limitations in terms of drift and sensitivity. Two VCSELs are characterized and a cubic polynomial relationship between current and wavelength is proposed. Perturbations from external factors are studied and favourable op- erating conditions based on minimum perturbations are suggested. Simulation studies as well as real-time experiments are performed to evaluate the perfor- mance of the system. The influence of algorithmic parameters on the fitting algorithm and the efficacy of the detection system with respect to measurand concentration is evaluated. The proposed detection system is found to be an optimized system in terms of accuracy and preci- sion for the resonance peak detection of the MRRs without any increased demand for cost and computation time.
Item Type:Essay (Master)
Faculty:EEMCS: Electrical Engineering, Mathematics and Computer Science
Subject:51 materials science
Programme:Electrical Engineering MSc (60353)
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