Results from the Quantum C100, a Novel CMOS Detector Optimisedfor 100 keV Cryo Electron Microscopy.

Session

Poster Session One

Authors

Deividas Krukauskas (3), Dr Mohamed El Sharkawy (1), Ben Marsh (3), Dr Tobias Starborg (2), Dr Jonathan Barnard (2), Matthew Hart (3), Craig Macwaters (3), Kara McNab (1), Dr Danail Vassiliev (1), Giulio Crevatin (1), Dr Ben Bradnick (1), Graham Dennis (1), Roger Goldsbrough (1), Prof. Angus Kirkland (2), Dr Liam O'Ryan (1), Dr Adriana L. Klyszejko (1), Dr Nicola Guerrini (3)

Affiliations

1. Quantum Detectors Ltd, Rutherford Appleton Laboratory, Harwell Campus, OX11 0QX
2. Rosalind Franklin Institute, Rutherford Appleton Laboratory, Harwell Campus, OX11 0QX
3. Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Campus, OX11 0QX

Keywords

the Quantum C100; C100; 100keV cryologies EM; 100 keV EM; electron microscopy; cryologies electron microscopy; democratise electron microscopy; 

Abstract text

Recent developments in direct electron detection technology are opening new research avenues in cryo–Electron Microscopy (cryo–EM). Faster and more efficient detectors significantly expand insights into the structure and function of biological molecules. Cryo–EM presents exciting opportunities to study proteins, protein complexes, organelles, drug delivery systems, cells and tissues in great detail. 

A study by Peet et al. quantifies the beam induced sample damage depending on the accelerating voltage of the microscope. It is evident that reducing the operating voltage from 300 keV to 100 keV significantly reduces sample damage and simultaneously allows for recovery of 25 % more structural information1. To date, the majority of structures deposited in the Electron Microscopy Data Bank (EMDB) with resolution better than 3 Å were determined using single particle approach at 300 keV accelerating voltage2,3. Importantly, transmission electron microscopes (TEMs) operating at 300 keV are expensive to purchase and maintain, therefore, putting them out of reach for many researchers and present a significant barrier to discovery4.

100 keV TEMs offer a solution for democratic access to structure determination. Until last year,  there was a paucity of suitable detectors optimised for 100 keV operation5. Here, we present first data from our newest direct electron detector optimised for 100 keV work, the Quantum C100.

The Quantum C100 was specifically optimised with 100 keV accelerating voltage in mind. Main characteristics of the ideal detector are high detective quantum efficiency (DQE) and modulated transfer function (MTF). These critical parameters are greatly improved by de novo design of the pixel itself. 

It contains a wafer scale CMOS sensor with a gapless array of 2048 x 2048 pixels and 54 um pitch. The large area is combined with a 2000 fps frame rate, resolution of 12 bits and maximises performance in integrating and counting modes. The initial results from our experiments characterising the first full size sensor using 100 keV electrons are shown. 

Authors wish to thank Dr. Richard Henderson, Dr. Chris Russo, Dr. Greg McMullan and members of the Henderson and Russo groups at Medical Research Council – Laboratory of Molecular Biology MRC – LMB in Cambridge for their support and crucial scientific guidance. We would like to thank Dr. Tom Burnley from CCP-EM team at STFC for his help and advice. We thank Matthew Callahan, Josh Wilkes, Dr. Olivia Sleator, Chloe Brine and the R & D, Sales & Marketing and Operations teams at Quantum Detectors Ltd, for their outstanding contribution to this work.

References

References

1. M. J. Peet, R. Henderson, C. J. Russo, ‘The energy dependence of contrast and damage in electron cryomicroscopy of biological molecules’, Ultramicroscopy 203 (2019) 125–131.

2. M. A. Herzik, M. Wu, and G. C. Lander, ‘Achieving better-than-3-Å resolution by single-particle cryo-EM at 200 keV’, Nat. Methods, vol. 14, no. 11, Art. no. 11, Nov. 2017, doi: 10.1038/nmeth.4461.

3. EMDB, ‘Electron Microscopy Data Bank’, Electron Microscopy Data Bank. https://www.ebi.ac.uk/emdb/ (accessed Feb. 16, 2022).

4. K. R. Vinothkumar and R. Henderson, ‘Single particle electron cryomicroscopy: trends, issues and future perspective’, Q. Rev. Biophys., vol. 49, ed 2016, doi: 10.1017/S0033583516000068.

5. K. Naydenova et al., ‘CryoEM at 100 keV: a demonstration and prospects’, IUCrJ, vol. 6, no. 6, Art. no. 6, Nov. 2019, doi: 10.1107/S2052252519012612.