College of Arts & Science -Department of Physics

Research Outline
Measuring interactions of light with matter is the oldest technique for observing our universe and is the bedrock nearly all sub-disciplines of physics including astronomy, condensed matter and quantum physics. Research at the OSIM laboratory involves measuring, controlling and manipulating light to get information about the properties of living systems. Our research involves developing techniques to elucidate structural or functional properties of macro-scale, complex, biological media. Research projects in the OSIM lab typically fall under one of three umbrellas:
  1. Developing or designing novel instrumentation
  2. Developing theoretical or numerical analytical techniques
  3. Exploring applications of the above for biomedical sensing
Since we are motivated primarily in building instruments and techniques that can advance clinical sensing of tissue health (or disease), these different areas must all be connected to be impactful. Our research is highly interdisciplinary and integrates experimental optical techniques with rigorous theoretical and computational approaches to provide objective, quantitative and dynamic information about the (bio)physical nature of the system being investigated. We are also particularly interested in ultimately keeping the cost of developed optical devices low so that they may be useful in ambulatory and/or low-resource settings. Projects in the group range from laboratory-based proof-of-concept studies all the way through practical applications of constructed devices in clinical or translational research studies.
Currently, we have ongoing collaborative research studies with faculty across several departments at Miami (including Physics, Biomedical Engineering and Psychology) as well as with faculty at the University of Michigan and the School of Medicine at the University of Cincinnati.

Active Project Areas
Estimating tissue optical properties
Our visual perceptions of the "color" of an object fundamentally arises from how the object scatters and absorbs light. The field of tissue optics involves being able to accurately and quantitatively determine these properties, for biological (tissue) media. The prescription for achieving this is to first obtain appropriate experimental measurements of the object of interest and then to theoretically analyze the measurements to extract the optical coefficients. There are several different experimental methods to achieve this with each one having associated theoretical approaches for analysis.
We explore a wide variety of such methods by combining previously well-established techniques along with discovering novel ways to improve and optimize them. In particular, we explore spatially-, spectrally- and temporally-resolved diffuse reflectance and fluorescence measurements as experimental tools and use theoretical constructs such as radiative transport, photon-diffusion and Monte Carlo methods for analysis.
Detecting Sub-surface Flow
Lasers are special because they emit radiation that is uniquely different from other light sources - in physics, this is called coherence. Coherent light has a characteristic speckled pattern, evident to most of us who've look at the light from a laser pointer closely. There are many interesting statistical properties of speckle that can be exploited to observe behavior of materials across time-scales ranging from nanoseconds to minutes.
We explore applications of coherent imaging for imaging sub-surface flow in tissue. On going work, explores two such approaches - laser speckle contrast imaging and diffuse correlation spectroscopy - to measure blood flow.
Low cost optical diagnostics
Advances in modern consumer electronics (smartphones, flat-screen displays) and telecommunications (routers, network switches) have driven the size and cost of optical components very low. These advances open up significant possibilities to build optical devices and tools at previously unimaginable ways. We explore prospects of leveraging such technologies to build miniaturized optical tools capable of high-quality biomedical sensing. Projects seek to translate these devices to provide point-of-care in ambulances, tertiary clinics, battlefields and in personalized-health.
In Vivo Studies
Ultimately, the impact of optical techniques for biosensing is in bringing them to address and advance medicine. All of the methods we develop at OSIM are targeted toward specific applications - either to answer basic biological questions in preclinical studies, or to help improve quality of diagnosis. treatment or care at the clinic. We collaborate with biologists, clinicians, psychologists, neuroscientists, biomedical engineers and nurses in testing the utility of the optical methods for specific applications. Ongoing studies involve developing techniques to measure human cognition, improving patient care at long-term care facilities and testing susceptibility of specific genetic markers for risk of brain strokes.

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