24 such hanging drop experiments are set up in a Linbro plate. A kit of different screening solutions, a set-up Linbro plate, dialysis buttons and a micro batch plate behind a goniometer head. A drop of this mixture is put on a glass slide which covers the reservoir. As a result the concentration of both protein and precipitant in the drop slowly increases, and crystals may form. There is a variety of other techniques available such as sitting drops, dialysis buttons, and gel and microbatch techniques.
Robots are useful for automatic screening and optimization of crystallization conditions.
The main advantage is the small sample size a crystallization robot can handle reproducibly, but it needs some effort to set it up. The chances for success in crystallizaion experiments depend strongly on the conformational purity of a protein. A single band on a denaturing SDS gel is a good sign, but Dynamic Light Scattering and Circular Dichroism help to learn about the aggregation and dispersity or the folding of your protein sample. Follow the links for more.