Our work is enabled by a number of portable and bedside optical imaging platforms based on the following techniques:

Oxygenation and Tissue Composition

Near-Infrared Spectroscopy (NIRS): NIRS systems non-invasively measure dynamic changes in oxygenation by looking at the fluctuations in intensity of near-infrared light. Due to the low absorption of light in this wavelength range, NIRS can penetrate centimeter depths and is sensitive to changes in brain and muscle tissues. Systems that use steady illumination of light, also know as continuous wave (CW) NIRS, are limited to looking at relative oxygenation changes but can be built into wearable form factors with high acquisition speeds. Advanced NIRS techniques, such as frequency-domain (FD) or time-domain (TD) NIRS, allow absolute quantification of molecular species and can also be utilized to look at water and lipid concentrations.

Spatial Frequency Domain Imaging (SFDI): SFDI is a wide-field functional imaging technique that uses spatially modulated light to provide quantitative information about tissue composition and structure. 

Diffuse Reflectance Spectroscopy (DRS): DRS uses light that is reflected back through the surface of tissue to determine localized tissue content including tissue oxygen saturation.

Blood Flow

Laser Speckle Contrast Imaging (LSCI): LSCI utilizes the interference pattern of coherent laser light to enable assessment of blood flow dynamics in tissue, particularly in the microvasculature.

Laser Doppler Flowmetry (LDF): LDF is a non-invasive technique for measuring blood flow in the microcirculation. LDF relies on the Doppler shift principle where light scattered by moving blood cells causes a frequency shift proportional to their velocity.

Diffuse Correlation Spectroscopy (DCS): DCS is an emerging noninvasive optical technique that measures the intensity fluctuations of moving blood cells to quantify tissue perfusion.

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