A sensing shelf for the VPrep pipetting station expands the system's versatility, making it suited for complex pipetting sequences while achieving high throughput. The shelf configuration can be used to sense if a microplate is present prior to processing, eliminating the possibility of pipette head crashes. Other shelf configurations include an alignment shelf that ensures precise positioning of labware. The station actively holds the plate while under the pipette head and then releases it once processing is completed. The shelf uses a vacuum to hold a range of plates down to ensure reliable pipetting in every well.