Pipettes are used to deliver small measured volumes of liquid. They include several manually operated instruments including a simple Pasteur pipette, graduated pipettes and the considerably more accurate volumetric pipettes. Pipette controllers are devices attached to a conventional pipette to allow more user friendly and accurate operation. They enable the user to rapidly fill and release the pipette, using squeezable bulbs, buttons or thumb wheels. They may be mechanical but are more commonly battery operated. Both pistol and linear designs are available.
With manual pipettes there is a very clear tradeoff between volume range and accuracy: the accuracy of graduated pipettes increases as the volume decreases, while the more accurate volumetric pipettes are suited to only a very narrow volume range. With a pipette controller it is possible to accurately dispense liquids over a wide range of volumes. This can greatly reduce the number of different pipettes required in the lab, resulting in a more lean and organized environment. There are also significant benefits for calibration, with fewer instruments needing to be calibrated and operator variation greatly reduced.
Pipette controllers can also increase productivity and ergonomics. They often provide different modes in addition to simple pipetting, which can automate operations such as mixing, diluting and multi-dispensing. It may even be possible to program in complex pipetting protocols. Hand strain is reduced by significantly reducing hand movement, as well as enabling more neutral hand positioning.
One potential disadvantage is that pipette controllers may run out of battery in the middle of a procedure. However, it is good practice to place pipette controllers on charging stands when not in use so they are always fully charged ready for use. Battery replacement may be required after years of use but this should be carried out preemptively as part of a calibration schedule.
An alternative to a pipette controller is the integrated electronic pipette which automatically delivers a preset volume from a self-contained instrument. This may be the only option where a multichannel pipette is required. Multichannel pipettes combine a number of separate pipettes in a row enabling them to be dispensed simultaneously, with each typically dispensed into one of a number of tubes arranged in a row on a test rack.