Label-free route to rapid, nanoscale characterization of cellular structure and dynamics through opaque media

We report a novel technique for label-free, rapid visualization of structure and dynamics of live cells with nanoscale sensitivity through traditionally opaque media. Specifically, by combining principles of near-infrared (NIR) spectroscopy and quantitative phase imaging, functional characterization of cellular structure and dynamics through silicon substrates is realized in our study. We demonstrate the efficacy of the new approach by full-field imaging of erythrocyte morphology in their native states with a nm path length sensitivity. Additionally, we observe dynamic variations of human embryonic kidney cells, through a silicon substrate, in response to hypotonic stimulation with ms temporal resolution that also provides unique insight into the underlying biophysical changes. The proposed technology is fundamentally suited for high-performance investigations of biological specimens and significantly expands the options for visualization in complex microfluidic devices fabricated on silicon.