Atmospheric plasma jet device for versatile electron microscope grid treatment

Atmospheric pressure plasmas have been widely applied in surface modification and biomedical treatment due to its ability to generate highly reactive radicals and charged particles. In negative-stain electron microscopy (Neg-EM) and cryogenic electron microscopy (cryo-EM), plasmas have been used in eliminating the surface contaminants as well as generating the hydrophilic surface to embed the specimen on grids. Plasma treatment is a prerequisite for negative stain and quantifoil grids, which are coated with hydrophobic carbon on the grid surface. Here we introduce a non-thermal atmospheric plasma jet system as an alternative new tool for surface treatment. Unlike the conventional glow discharger, we found that the plasma jet system successfully cleans the grid surface and introduces hydrophilicity on grids in the ambient environment without introducing a vacuum. Therefore, we anticipate the plasma jet system will be beneficial in many aspects, such as cost-effective, convenient, versatile, and potential applications in surface modification for both negative stain and cryo-EM grid treatment. ### Competing Interest Statement The authors have declared no competing interest. *