Innovative Projects Realized

Optical Spectroscopy of Nanomaterials

The project is aimed at exploring various physical properties on the nanoscale using optical spectroscopy. In particular a focus on Raman and Optical spectroscopy of nano materials and bulk compounds on the nanoscale to better understand the interplay between numerous physical processes. This not only allows us to explore the basic physical underpinnings of novel effects but better characterize and optimize devices. Three different materials will be the focus of this study, high temperature superconductors, topological insulators and semiconductor nano wires. All three offer unique opportunities to study the emergence of new properties as a material is tuned on the nano scale, while also offering dramatic improvements in multifunctional materials, quantum computation, loss-less energy transmission and thermoelectric power generation.

Particular focus will be given to the Raman spectroscopic response of these materials. Raman is a powerful technique as it can measure the lattice, magnetic, thermal and electronic properties of a material simultaneously. Furthermore every material has a unique Raman signature and thus Raman can be used to “fingerprint” an unknown compound or map out the composition over a large area. This is all achieved through the scattering of a focused laser beam, providing spatial resolution of 1 micron. Recently our group has begun to couple a Raman system with a scanning probe microscope enabling us to measure the Raman response with 10nm resolution. This unparalleled performance will provide key insights into the role of nanoscale inhomogeniety in novel properties as well as fully characterize single nano materials (quantum dots, nano wires, exfoliated material). For example this Tip Enhanced Raman Spectrometer (TERS) can simultaneously map the local temperature, strain and chemical composition of a material or device on the nanoscale. These TERS spectra will be acquired while operating the device to better understand the real limits of its performance as well as the origins of novel behaviour that emerges.

Quantifying stratified turbulence in gravity currents

The student working on this project will determine how the internal mixing dynamics influence the degree to which gravity currents entrain fluid. Gravity currents are important flows for oceanography that form when dense water cascades down the continental slope. There are also many important engineering applications, such a dense waste-water disposal from a desalination plant, or the fate of underwater turbidity currents.

The student will conduct laboratory experiments using particle image velocimetry, an acoustic Doppler velocimeter and a high resolution density measurements to measure the small-scale density and velocity fields to test our previous predictions on how entrainment rate and the internal mixing dynamics depends upon the bulk entrainment rate of gravity currents.

It is anticipated that within the 12 week program that enough experimental data will be collected to result in subsequent peer reviewed journal publication.

Comparative genomics to identify function associations

Many microbial genomes have been completely sequenced. The presence/absence data for thousands of genes across a diverse array of species allow one to quickly identify genes that are functionally associated. Because of shared ancestry among biological species, such functional association needs to be phylogenetically controlled. The computation requires the construction of a reliable species tree, map the presence/absence data onto the tree, and test two Markov chain models, one assuming no functional association (with four parameters) and the other assuming association (with eight parameters) by a likelihood ratio test. In the past, this has been done only for small data set in a semi-automated way. This project will create a computer program to automate the entire process. Students in this project will learn the general conceptual framework as well as the relevant knowledge of stochastic processes and statistical estimation methods to facilitate their future participation as graduate students.

Extracting the mechanical properties of materials as small scales using ultrafast lasers

In order to accurately predict the mechanical properties of materials, it is necessary to obtain the true stress-strain curve of the material until failure. If the material is heterogeneous, more parameters are required including the true stress strain curve of all phases in the material and the strength of the interface between the various phases. This information is difficult to obtain though is it crucial for the modelling efforts.
In this project, the local mechanical properties of materials will be extracted from various materials using ultrafast laser machining combined with state of the art characterization techniques.

Ultrafast laser-matter interactions in metals and dielectrics

Ultrafast lasers and especially femtosecond lasers offers new possibilities in the field of micromachining as they allow precise machining with almost no collateral damage around the machined features. Furthermore, the pulse duration (<500fs) is smaller than the atomic vibration period of virtually all materials which results in unique laser/matter interactions. The research project will look at better understanding the surface features obtained after femtosecond laser irradiation of metals and dielectrics. This includes ripple formation, microvoids formation, nano and microstructure modification, etc. In particular, two beam interference will be used to better control the morphologies obtain after irradiation.

Computer Simulation of Bacteria Swimming in Various Fluidic Systems

Bacteria and cells have different swimming abilities and strategies. It has been shown that it is possible to design funnel-shaped fences in microfluidic systems that force swimming cells to concentrate on one side of the fence. This is not unlike how lobster are captured!

In this project, we will simulate the swimming of hundreds of interacting cells in the presence of various geometrical features in order to optimize their separation.

Time permitting, we will also examine the role of chemotaxis (cells tend to swim towards food sources) and cell-cell interactions (cell tend to synchronize their swim).

Motion of a particle in a solution containing “thick” and “thin” regions

When a group of particles is released in a fluid, they will disperse throughout the solution via diffusion. If we consider a solution that is “thick” (like honey) in some regions and “thin” (like water) in others, where will the particles end up? Will they become trapped in the honey, concentrated in the water where they move freely, or evenly distributed throughout? It turns out the answer depends on the details of how the interface between the thick and thin regions are treated. In this project, simulation and numerical techniques will be employed to investigate the diffusion of particles in 2D systems containing regions of different viscosities. The relative concentrations and effective diffusion coefficients of particles in “patchy” (random viscous inclusions of various sizes) or “ordered” (eg., stripes alternating thick and thin) arrangements will be studied. Results will be generated for several treatments of the interfaces. Considering application to the release of drugs within biological systems or the dispersion of particulate matter in food preparation and aging, which approach is most physical? What do these results tell us about the efficiency of delivering drugs or mixing substances? Can we design configurations to control the mixing or even separate particles based on their size?

Connecting Wealth to Health for Retiring Older Adults

The project aims to increase awareness associated with health related financial costs in aging; and enhance the capacity to self-manage post-retirement. In the first phase, a study was conducted assessing the health and financial related needs of rural residents in pre-retirement (45-70 years old). The objective was to identify gaps in knowledge related to health care costs and finances, so suitable educational tools can be developed to aid individuals in decision making. In the second phase models of the educational tools (including technological and paper formats) will be developed and tests will be conducted to make improvements before wider distribution.

Galaxy populations in X-ray clusters

The X-ray X-tra Large (XXL) project is a astronomical research collaboration that aims to use a large X-ray survey of galaxy clusters to answer fundamental questions in cosmology and galaxy evolution. I am a key member of the XXL project and I specialise in using multi-wavelength observations of galaxies in X-ray emitting clusters to learn about their formation and evolution. Previous student projects associated with the XXL survey have included a) creating a computer algorithm to identify galaxy clusters as spatial over-densities of characteristically red galaxies as observed in optical images in order to compare their properties to clusters identified at X-ray wavelengths, b) performing and reducing optical spectroscopy of individual galaxy clusters in order to determine their redshift, c) studying the population mix of red versus blue galaxies in clusters with a view to understanding the physical mechanism that causes the apparent transformation from a blue, star-forming galaxy to one which is red and passive. I have a range of similar projects suitable for a MITACS student including a) the analysis of near-infrared images of very distant clusters to learn about the physical structure of so-called brightest cluster galaxies and b) the comparison of cluster catalogues generated using optical observations and X-ray wavelengths with a view to understanding what makes a cluster of given mass detectable at X-ray wavelengths or not. I anticipate that the exact nature of any project to be investigated would be discussed and refined with any interested participant.

Technology to improve the quality of life of those with disabilities

The project will focus on the development of computer interfaces, tools and applications that are directed at improving the quality of life and independence of persons with disabilities. The suit of tools under development include; 1) Task management and organizational apps, and journal (record keeping and diary) applications that support individuals with cognitive challenges- including those with brain injuries and those with early stage dementia. 2) A simple and automated Skype interface (“CanConnect) that allows people unfamiliar with, or unable to use computers to connect (via audio and video interaction) with family, friends or caregivers using Skype. 3) A wayfinding and navigation tool (CanGo) that allows users (for example those with cognitive challenges or those with visual impairments) to use the public transit system to travel to and from school, the workplace to or visit friends).

The construction of a rapid-scan mid-infrared Mueller matrix ellipsometer for the study of protein adsorption at the solid-liquid interface

The proposed project involves the design and construction of a real-time broadband infrared Mueller-matrix ellipsometer for the study of protein adsorption at the solid-liquid interface. By preparing an incident light field in a well-defined polarization state, and then characterizing the change in polarization that occurs upon interacting with a sample (for example, in a reflection geometry), it is possible to learn about many structural details of the molecules that interacted with the beam. This field in general is called polarimetry or ellipsometry. A recently-published technique from our group is capable of measuring all elements of the polarization transfer matrix, in the mid-infrared from 400-4000 wavenumbers. This is especially interesting since this region of the spectrum corresponds to molecular vibrations. As a result, analysis of the polarization fingerprints we observe can be directly related to sub-molecular features. If results corresponding to the vibration of a particular chemical functional group are analyzed quantitatively, it is possible to construct a distribution for the molecular bond orientation. If this is performed for multiple vibrational modes, we learn about the shape of molecules at the solid-liquid interface. Applications include investigating the biocompatibility of polymeric medical implants, thereby studying the propensity for protein denaturation upon adsorption at the polymer-aqueous interface. Although our existing experiment is powerful, and has demonstrated the proof-of-principle, it is slow, thereby limiting its applications to many scientific problems. The MITACS student working on this project would develop an instrument with the same capability, but of an entirely different design. Four photoelastic modulators (piezoelectric crystals) would be employed in order to modulate the light at various frequencies. Demodulation of the signals would then be performed in order to extract the optical, physical, and ultimately chemical properties of interest.

Optical Trapping of Nanoparticles and Optical Antennas

The student can choose between two sub-projects. The first involves our recent discovery of optical trapping of nanoparticles that is 10000 times more efficient than past methods. With this improvement we can trap, detect and manipulate even single proteins. We are studying the capability of this unique trapping configuration, which will be the research task of the student. The second project involves design of antenna like structures for the visible-infrared regime. These antennas will be of interest to single photon sources and enhanced photovoltaics (solar cells).