Shake-it-off: a simple ultrasonic cryo-EM specimen-preparation device

Acta Crystallogr D Struct Biol. 2019 Dec 1;75(Pt 12):1063-1070. doi: 10.1107/S2059798319014372. Epub 2019 Nov 22.


Although microscopes and image-analysis software for electron cryomicroscopy (cryo-EM) have improved dramatically in recent years, specimen-preparation methods have lagged behind. Most strategies still rely on blotting microscope grids with paper to produce a thin film of solution suitable for vitrification. This approach loses more than 99.9% of the applied sample and requires several seconds, leading to problematic air-water interface interactions for macromolecules in the resulting thin film of solution and complicating time-resolved studies. Recently developed self-wicking EM grids allow the use of small volumes of sample, with nanowires on the grid bars removing excess solution to produce a thin film within tens of milliseconds from sample application to freezing. Here, a simple cryo-EM specimen-preparation device that uses components from an ultrasonic humidifier to transfer protein solution onto a self-wicking EM grid is presented. The device is controlled by a Raspberry Pi single-board computer and all components are either widely available or can be manufactured by online services, allowing the device to be constructed in laboratories that specialize in cryo-EM rather than instrument design. The simple open-source design permits the straightforward customization of the instrument for specialized experiments.

Keywords: 3D printing; CNC milling; Raspberry Pi; cryo-EM; self-wicking grids; specimen preparation; ultrasonic.

MeSH terms

  • Cryoelectron Microscopy / instrumentation*
  • Macromolecular Substances / chemistry*
  • Proteins / chemistry*
  • Software
  • Specimen Handling / instrumentation*
  • Vitrification


  • Macromolecular Substances
  • Proteins