The MPCS-beta is controlled by a computer running MicroPlugger software. Four different operational modes are available to provide fully customizable crystallization screening using the MPCS™: (i) Priming Mode, (ii) Constant Mode (for reproduction of identical crystallization experiments, (iii) Gradient Mode (for generation of smooth concentration gradients and (iv) Hybrid Mode (for sparse matrix + gradient screening in one experiment). Once the card is primed and a method is activated, the MPCS fills an entire CrystalCard without user intervention.