Supplementary document for High Efficiency Vertically Emitting Grating Coupler Facilitated by Three Wave Interactions - 6944995.pdf

Analytical Modeling and Design Parameter

Fast Stiffness Mapping of Cells Using High-Bandwidth Atomic Force Microscopy

The cytoskeleton controls cellular morphology and mediates the mechanical interactions between a cell and its environment. Atomic force microscopy (AFM) has the unique capability to map cytoskeletal mechanics and structures with nanometer resolution. However, whole-cell cytomechanical imaging with conventional AFM techniques is limited by low imaging speed. Here, we present fast nanomechanical mapping of cells using high-bandwidth AFM (HB-AFM), where >10⁶ nanoindentation measurements were acquired in ∼10 mina task that would take weeks to finish using conventional AFM. High-bandwidth measurements enabled capture of the entire tip–sample interaction for each tap on cells, engendering a new measurement (“force phase”) that exceeds the contrast of conventional tapping mode and enabling spectral visualization of >10 harmonics. The abundance of measurements allowed discovery of subtle cytomechanical features, including the stiffness of fibers of the cellular spectrin network <i>in situ</i>. This approach bridges HB-AFM and high-harmonic imaging and opens future opportunities for measuring the dynamic mechanical properties of living cells

Contracting cardiomyocyte measured with quantitative phase imaging

Time-series of quantitative phase images showing a contracting cardiomyocyte at 50 fps. These images were acquired using diffraction phase microscopy. The colormap shows optical path difference measured between the cell and surrounding medium