This system is used to prepare/dry delicate biological samples, particularly those which may distort upon loss of fluid content. It is an alternative to using freeze drying.  The technique uses one of the unusual property of supercritical fluids, that they do not form a meniscus, and therefore do not create meniscus forces.  Liquid CO2 replaces the water in the sample, then the sample is brought beyond the critical point, then the pressure is relieved, allowing the CO2 to exit the sample, leaving it dry and undistorted by the capillary and meniscus forces present in most fluids, particularly aqueous solutions.