Multipurpose Silicon-chip Flow Cell for Liquid Transmission Electron Microscopy and Related Analysis

We describe the development and applications of a flow cell chip for liquid transmission electron microscopy (TEM) for imaging nanoparticles, biological samples, and dynamic phenomena such as the freezing and melting of liquids, and Raman scattering measurements. The liquid flow cell (LFC) consists of two silicon chips with silicon nitride windows that sandwich two flexible microtubes. Notably, our LFC can be removed from the TEM holder for analysis with other instruments, whereas conventional LFC cannot be removed from the TEM holder for post-experiment analysis. Furthermore, currently available commercial solution holders only allow a portion of the flowing solution to enter the cell, but our LFC has observation windows in the flow channel that make it easier to control the experimental conditions. Importantly, we also describe the results of using our LFC chip for imaging the freezing and melting of water that was slowly cooled by a Peltier element to initiate freezing or heated to induce melting. This research shows that our LFC is a powerful component for imaging the temperature dependence of materials at the nanoscale for a wide range of applications including combining TEM with light scattering analysis of materials such as Raman spectroscopy.