Date of Award
Doctor of Philosophy
This report covers more than three years of my academic journey toward earning my Ph.D. in Mechanical Engineering. I have had opportunity to conduct different research related to the application of plasmonic structure in both photonics and biomedical branches. We designed, fabricated and characterized a novel freestanding gold membrane emitter that shows a narrowband infrared emission the near-IR and mid-IR wavelength ranges from 2.5 µm to 5.5 µm. The Au-membrane device shows a transmission coefficient as high as 76.8% and an absorption coefficient of 23.1%. The plasmonic gold-membrane device can be used as a low-cost, lightweight narrowband infrared light source, biomolecular sensor and thermal detector. We also designed and fabricated a narrowband thermoelectric detector by integrating a guided-mode absorbing filter and an on-chip thermocouple which works based on the Seebeck coefficient phenomena. The guided-mode filter exhibits a narrowband optical absorption with a resonant absorption coefficient of 85.4% and a full-width-half-maximum of 14.8 nm in the visible wavelength range. The device also exhibits a responsivity and noise equivalent power of 0.26 V W-1 and 7.5 nW Hz-1/2, respectively. The thermoelectric device can be implemented to provide spectral information during an analysis. In terms of biomedical applications of plasmonic structures, we designed and fabricated an optical-based quantitative polymer chain reaction device to amplify nucleic acids. The device is fully automated and controlled by a simple Arduino Uno R3 micro-controller. A 3W 808 µm laser source is used to heat up the PCR solution. A customized plasmonic chip is designed to absorb the incident light and convert it into heat. The plasmonic chip is also equipped with an on-chip thermocouple which allows us to do real-time temperature monitoring. We successfully amplified different genes with 155 to 722 bp product length using our device, with an efficiency of 98%. We also designed an AMR gene analyzer which allows us to study antimicrobial resistant genes using DNA microarrays. The designed apparatus consists of several sub-assemblies including a thermal management unit, a xyz- motion control sub-system, fluorescence imaging unit, illumination sub-system and a main controller which syncs all the sub-assemblies. An asymmetric PCR has been employed to replicate Cy3-labeled single strand target DNAs’ concentration. The amplification step has been followed by a constant hybridization temperature and finally with a melting test which allow us to detect genomic mutation using melting curve analysis. The device has a 120W heating and cooling module with an average 5°C/sec heating and cooling rate and 0.1°C resolution. A 532nm laser beam with a 500mW output power were used to excite Cy3-labeled target genes. A 5-megapixcel CMOS camera has been used to capture fluorescence signals of hybridized excited target genes. The device successfully amplified 8 different AMR genes extracted from Acinetobacter baumannii, Klebsiella pneumonia, Escherichia coli, and Campylobacter. The mutation study successfully detected a 1.5 °C melting temperature difference between wild-type and mutant-type gyrA genes of Campylobacter jejuni.
Monshat, Hosein, "Application of plasmonic devices in spectroscopy and biomedical studies" (2020). Graduate Theses and Dissertations. 18363.
Available for download on Friday, January 07, 2022