A glow discharge unit to render electron microscope grids and other surfaces hydrophilic

We describe the design, construction, and operation of a simple glow discharge unit that can be used to make surfaces such as carbon-coated electron microscopy grids and glass coverslips hydrophilic. The use of a vacuum leak detector (Tesla coil) in place of a conventional high-voltage power supply and a small plastic desiccator for the vacuum chamber make the unit very inexpensive. Owing to the small volume of the chamber and the simplicity of the unit, the whole glow discharge process can be carried out in only 2 to 3 min, a time considerably shorter than that required for conventional vacuum evaporators. The hydrophilic surface improves adsorption of particles by several orders of magnitude in preparation for negative staining, freeze-drying, and other procedures.