Scalable and cost-effective optical components for biosensing applications

Cost-effectiveness has been a key factor in consumer biophotonics. In this talk, I will discuss two approaches for overall cost reduction. First, I will introduce a highly porous yet monolithic plasmonic nanosurface that features intense and high-density hot spots, large surface area, and high structural integrity and reproducibility. The fabrication process of this nanosurface is of low-cost and highly scalable. Using localized surface plasmon resonance (LSPR) and coupling modes, enhanced light-matter interactions near the nanosurface can be realized. The surface enhancement results in stronger signal which reduces the burden on high-end optical detection systems. We have applied them to several analytical Chem/Biosensing platforms for a range of sensing targets by various spectroscopic and imaging techniques. Nanoplasmonic sensors appear to provide potential solutions in a range of applications from precision medicine to point-of-care diagnostics and wearable technologies. In the second approach, we have developed an “inkjet printing” process for making polymer lenses which enable high quality microscopic imaging using smartphones – High performance microscopy of nanoscale objects and molecular species can be carried out on $10 phones. Finally, I will discuss the synergy of plasmonic enhancement and smartphone microscopy in the context of consumer biophotonics

Taiwanese planning law : a historical review and comparison with Hong Kong

This thesis compares the evolution of urban planning systems and related laws that operate within Taiwan and Hong Kong. By conducting a historic review, this thesis studies how planning laws and urban plans have been made, shaped and written, as well as their effects on spatial development. Borrowing from Patrick McAuslan’s “Ideologies of planning law” concept, this thesis observes that planning laws are compromised products of domestic and foreign socio-political forces beyond planners’ control, with three competing ideologies (private property, public interest and public participation) dominating at various stages of the respective planning systems. On the surface, the private property and public interest ideologies appear to contradict each other. However, historically examining the implementation of urban planning by the developmentalist states of Taiwan and Hong Kong reveals that both ideologies have and still do serve the interests of certain power blocs and property developers. While the public interest ideology was upheld, the racial factor and sanitation syndrome present in the urban regularisation resulted in spatial apartheid and the ideology serving the interests of the colonial forces occupying each territory; while the private property ideology was upheld, the betterment of certain people’s property right was built on less privileged people’s losses. Researching the interaction between building violations and informal housing concludes that laws can be arbitrary and fluid in practice, with the line of legality having to be drawn and redrawn. With disadvantaged people living in informal housing, building violations eased government responsibility in relation to the burden on housing and intervening in the property market. While the first two ideologies sustain the existing capitalist system with an emphasis on a functional property market, the third ideology has the potential to become an oppositional ideology to the status quo if planners acknowledge that planning law is not apolitical but an arena for challenging the existing administration

Constrained regularization for noninvasive glucose sensing using Raman spectroscopy

Multivariate calibration is an important tool for spectroscopic measurement of analyte concentrations. We present a detailed study of a hybrid multivariate calibration technique, constrained regularization (CR), and demonstrate its utility in noninvasive glucose sensing using Raman spectroscopy. Similar to partial least squares (PLS) and principal component regression (PCR), CR builds an implicit model and requires knowledge only of the concentrations of the analyte of interest. Calibration is treated as an inverse problem in which an optimal balance between model complexity and noise rejection is achieved. Prior information is included in the form of a spectroscopic constraint that can be obtained conveniently. When used with an appropriate constraint, CR provides a better calibration model compared to PLS in both numerical and experimental studies

Taiwanese planning law : a historical review and comparison with Hong Kong

This thesis compares the evolution of urban planning systems and related laws that operate within Taiwan and Hong Kong. By conducting a historic review, this thesis studies how planning laws and urban plans have been made, shaped and written, as well as their effects on spatial development. Borrowing from Patrick McAuslan’s “Ideologies of planning law” concept, this thesis observes that planning laws are compromised products of domestic and foreign socio-political forces beyond planners’ control, with three competing ideologies (private property, public interest and public participation) dominating at various stages of the respective planning systems. On the surface, the private property and public interest ideologies appear to contradict each other. However, historically examining the implementation of urban planning by the developmentalist states of Taiwan and Hong Kong reveals that both ideologies have and still do serve the interests of certain power blocs and property developers. While the public interest ideology was upheld, the racial factor and sanitation syndrome present in the urban regularisation resulted in spatial apartheid and the ideology serving the interests of the colonial forces occupying each territory; while the private property ideology was upheld, the betterment of certain people’s property right was built on less privileged people’s losses. Researching the interaction between building violations and informal housing concludes that laws can be arbitrary and fluid in practice, with the line of legality having to be drawn and redrawn. With disadvantaged people living in informal housing, building violations eased government responsibility in relation to the burden on housing and intervening in the property market. While the first two ideologies sustain the existing capitalist system with an emphasis on a functional property market, the third ideology has the potential to become an oppositional ideology to the status quo if planners acknowledge that planning law is not apolitical but an arena for challenging the existing administration

Noninvasive glucose sensing by transcutaneous Raman spectroscopy

We present the development of a transcutaneous Raman spectroscopy system and analysis algorithm for noninvasive glucose sensing. The instrument and algorithm were tested in a preclinical study in which a dog model was used. To achieve a robust glucose test system, the blood levels were clamped for periods of up to 45 min. Glucose clamping and rise/fall patterns have been achieved by injecting glucose and insulin into the ear veins of the dog. Venous blood samples were drawn every 5 min and a plasma glucose concentration was obtained and used to maintain the clamps, to build the calibration model, and to evaluate the performance of the system. We evaluated the utility of the simultaneously acquired Raman spectra to be used to determine the plasma glucose values during the 8-h experiment. We obtained prediction errors in the range of ∼1.5−2  mM. These were in-line with a best-case theoretical estimate considering the limitations of the signal-to-noise ratio estimates. As expected, the transition regions of the clamp study produced larger predictive errors than the stable regions. This is related to the divergence of the interstitial fluid (ISF) and plasma glucose values during those periods. Two key contributors to error beside the ISF/plasma difference were photobleaching and detector drift. The study demonstrated the potential of Raman spectroscopy in noninvasive applications and provides areas where the technology can be improved in future studies.National Science Foundation (U.S.) (CAREER Award (No. CBET-1151154))United States. National Aeronautics and Space Administration (Early Career Faculty Grant (No. NNX12AQ44G))Gulf of Mexico Research Initiative (GoMRI-030)Cullen College of Engineerin

Performance of line-scan Raman microscopy (LSRM) for high-throughput chemical imaging of cell population,”

We evaluate the performance of line-scan Raman microscopy (LSRM), a versatile label-free technique, for high-throughput chemical imaging of cell population. We provide detailed design and configuration of a home-built LSRM system developed in our laboratory. By exploiting parallel acquisition, the LSRM system achieves a significant throughput advantage over conventional point-scan Raman microscopy by projecting a laser line onto the sample and imaging the Raman scattered light from the entire line using a grating spectrograph and a charge-coupled device (CCD) camera. Two-dimensional chemical maps can be generated by scanning the projected line in the transverse direction. The resolution in the x and y direction has been characterized to be ∼600-800 nm for 785 nm laser excitation. Our system enables rapid classification of microparticles with similar shape, size, and refractive index based on their chemical composition. An equivalent imaging throughput of 100 microparticles∕s for 1 μm polystyrene beads has been achieved. We demonstrate the application of LSRM to imaging bacterial spores by identifying endogenous calcium dipicolinate. We also demonstrate that LSRM enables the study of intact microalgal cells at the colonial level and the identification of intra-and extracellular chemical constituents and metabolites, such as chlorophyll, carotenoids, lipids, and hydrocarbons. We conclude that LSRM can be an effective and practical tool for obtaining endogenous microscopic chemical and molecular information from cell population