High-speed three-dimensional measurement of dynamics of colloidal membranes using dielectric tensor holographic tomography

A colloidal membrane is one rod-length thick fluid monolayer that spontaneously assembles in presence of non-adsorbing polymer [1]. Including the transformation from a flat 2D colloidal membrane to an edgeless 3D colloidal vesicle, colloidal membranes undergo a range of remarkable morphological and topological shape changes, yet quantitative insight into such dynamics is limited due to the limitations of the existing imaging techniques. Here, we present a study on non-equilibrium dynamics of colloidal membranes by employing dielectric tensor tomography (DTT) [2]. By recording diffracted light from colloidal membranes for various illumination angles, the principles of DTT enables the reconstructing of the 3D tomograms of directors and principal refractive indices with high temporal resolution without fluorescence labeling or the mechanical scanning for 3D imaging. Using the technique, we investigated the forming and closing dynamics of transient pores on colloidal vesicles in response to changing osmotic pressure, and the orientational change of constituent rod particles around the pore. [1] Sharma P, et al. "Hierarchical organization of chiral rafts in colloidal membranes." Nature 513.7516 (2014): 77-80 [2] Shin S, et al. "Tomographic measurement of dielectric tensors at optical frequency." Nature Materials 21 (2022): 317-324