When you say something is boiling, most people assume that means it is hot, but materials can be made to boil at very low pressures as well. This physical fact has caused some problems for studying soft materials, which can boil away in the vacuums needed for tunneling electron microscopes to work. Researchers at Berkeley Lab however have found a system that allows the soft materials to be protected from the vacuum, without compromising the microscope's performance.
Normally protecting the soft material means placing it in a liquid cell with silicon-based viewing windows, but these cells can interfere with the performance of the microscope. The Berkeley researchers decided to develop a new kind of cell that uses graphene instead. Graphene is a one-atom thick sheet of carbon, and at that thickness it is transparent to the electron microscope. Also the shape of the graphene makes it highly susceptible to van der Waals forces, which will bind two sheets of graphene together, trapping the soft material in a much smaller liquid cell.
This setup allowed the researchers to image DNA strands connected to gold nanoparticles for two continuous minutes. That was enough time to put together a movie of the particles' movement, with atomic-scale resolution.
Source: Berkeley Lab