Development of a superfluid helium stage for high-resolution electron microscopy

The development of a new low-temperature stage for high-resolution electron cryo-microscopy is reported here. The stage is cooled down to 1.5 K by superfluid helium, and this cryo-microscope has enabled the authors to record images of chlorinated copper-phthalocyanine to a resolution of 0.26 nm at a stage temperature of 1.5 K. The low consumption rate of liquid helium of this cryo-stage has made possible the continuous operation of the cryo-microscope for more than 5 h without having to refill the cryo-stage tanks with liquid helium and liquid nitrogen. The stage has been tested for durability for more than 5 years. This electron cryo-microscope has also been equipped with an easily operated cryo-transfer device which has made possible the exchange of frozen-hydrated specimens under cryogenic conditions without any observable contamination.