Velocity11 offers a sensing shelf for its high-speed VPrep Pipetting Station that can be used to sense if a microplate is present prior to processing, and thus eliminating the possibility of costly pipette head crashes. The VPrep pipettor features a choice of interchangeable 96-, 384-, 8- or 16-channel pipetting heads. Eight sliding shelves are arranged on either side of the pipetting head permitting access to the plates, while conserving deck space. All quadrants of 96, 384, and 1536-well microplates can be accessed. Other shelf configurations include an Alignment Shelf that ensures precise positioning of labware. This is used primarily for 1536-well operations, and for low volume (small diameter) 384-well microplates. The shelf actively holds the plate while it is under the pipette head, releasing the plate once the processing is completed. A Vacuum Alignment Shelf eliminates problems in processing warped PCR plates. Vacuum is utilized to hold plates flat. A vacuum sensor ensures proper plate engagement prior to any liquid handling steps. A Weigh Shelf provides precise liquid level control for auto-filling reagent reservoirs. By monitoring the weight of the reservoir, it can control when the associated pump is activated. This ensures that the liquid level is always kept at an optimal location, and the reservoir is never overfilled.