Yodh’s research at Penn has spanned a wide range of fundamental and applied investigations in condensed matter physics, medical physics, biophysics, and optical science. This work includes early contributions to the nonlinear optics of solid-solid interfaces, and fundamental research in soft matter including studies of melting and frustration in colloids and liquid crystals, design and measurement of entropic forces, stabilization of carbon nanotubes in solution, and discoveries about the role of particle anisotropy in phenomena ranging from Brownian motion to coffee rings. He has also done pioneering work in biomedical optics, demonstrating and clinically translating concepts in light diffusion for noninvasive imaging and monitoring of tissue blood flow, hemodynamics, metabolic responses, and therapeutics in cancer and brain.