practical way.”

Ross is widely credited with moving liquid cells into the practical realm. As a researcher at IBM in the early 2000s, she and her colleagues created a holder with a silicon nitride pane that was thin enough to allow electrons to pass through relatively unimpeded. Since then, researchers have explored other materials for use in liquid cells, such as graphene.

At the Lawrence Berkeley laboratory, Zheng is leading a multimillion-dollar US Department of Energy programme dedicated to developing the technique further. She and others have trained a variation of a detector designed for cryo-EM on liquid samples. Among other targets, they are interested in the interface between battery electrodes and electrolytes — a crucial area in which problems such as the formation of metallic filaments called dendrites canunintended reactions. It is also difficult to measure quantities such as pH and temperature inside the microscope.

But others are heartened by the latest research on the effect of electron beams. Patricia Abellan, a materials scientist at SuperSTEM, a research centre and user facility for advanced microscopy in Daresbury, UK, says she has seen “a revolution in the understanding of the interaction of the electron beam with matter”, particularly in liquid systems. The change has been spurred in large part by collaborations with researchers who focus on studying materials affected by nuclear radiation. In the past few years, Abellan and others have explored how additives can control the growth of particles and alter pH, and how solvents other than water, such as toluene, might limit the effect of electron