Chapter Two - Progress and Development of Direct Detectors for Electron Cryomicroscopy

Abstract Recent progress in single-particle electron cryomicroscopy (SPEM) has seen a large increase in the number of biological macromolecular structures being solved at close to atomic resolution. An important role in that success has been played by the introduction of direct electron detectors, with higher detective quantum efficiency (DQE) at all spatial frequencies and continuous readout, which enables dose-fractionated movie-mode imaging. The higher DQE results in intrinsically better images, while the movie-mode imaging has been invaluable both in compensating for beam-induced specimen movement and in allowing the weighting of individual frames to maximize the overall signal-to-noise ratio of the exposure. Also crucial to the success of direct detectors was the development of sensors that have a wide field of view and sufficient radiation tolerance for use over long periods in the electron microscope. This chapter covers recent developments in detector technology, culminating in the availability of direct detector systems from multiple vendors which are now in daily use in many different laboratories.