The Microbatch technique does not rely on any equilibration for nucleation to take place. Instead, the assumption is made that in some of the conditions the protein already resides in the Nucleation Zone and crystal growth can occur. Drops are set up as per Vapour Diffusion but are not sealed against a larger reservoir of the precipitant. Instead, each drop is covered with oil (usually Paraffin, but sometimes Silicon oil or mixtures of the two) to prevent evaporation. Unlike Vapour Diffusion experiments, Microbatch experiments attempt to maintain the initial conditions in each drop. As such, protein concentrations do not increase as time goes by and the technique is comparatively gentle. Once an initial hit has been found, it has been suggested that Microbatch can be used to grow crystals superior to those obtained by Vapour Diffusion, although this is an area of debate.
One group within the Department has an Oryx robot which can be used to set up Microbatch experiments (it will also do Vapour Diffusion trays, but is slower than the Cartesian). The robot is also capable of being used to optimise initial hits - using 5 channels, each component of the condition can be varied independently to find the ideal crystal-growing environment for your protein! Training is strictly required before use of the Oryx!