Microcapillary pipettes, often called capillary micropipettes, are used to transfer small volumes of liquids. A type of capillary tube, microcapillary pipettes are graduated or calibrated for accurate and precise measurements, while capillary tubes are not graduated or calibrated. Capacities range from 0.2 microliters to 1,000 microliters. Micropipetting procedures are used in medical facilities to perform blood testing and deliver medications and in pharmaceutical laboratories and other research facilities to measure precise volumes of liquids at the microliter level. Made of plastic or glass, micropipettes are designed for one-time use. Sterile and non-sterile versions are available to meet user and lab requirements. Microcapillary pipettes often use a rubber plunger to deliver the liquid from the tube, ensuring that all liquid is evacuated from the chamber.
The term micropipette is used interchangeably to refer to a micropipette tube or to the micropipettor mechanism, the mechanism that is used to aspirate (collect) and deliver the required quantity of liquid. It is a single-channel or multichannel mechanism that measures precise volumes of fluid within a specified range. A single-channel mechanism measures liquid into one micropipette tube at a time, while multichannel mechanisms aspirate and deliver liquid to several receptacles at once. For example, a single-channel 20-microliter mechanism will aspirate and dispense liquid volumes between 2 and 20 microliters for one receptacle at a time, while a multichannel 20-microliter mechanism will dispense between 2 and 20 microliters of fluid to two or more receptacles with one depression of the plunger. A disposable micropipet tip is selected based on the required volume range and placed in the mechanism for filling. The mechanism is set to the required volume and when depressed, a plunger aspirates the set volume and holds it for delivery it to the receptacle.
Some features to consider when selecting a micropipette include capacity, aspirate and delivery mechanism, purpose or use, material construction, sterile or non-sterile, and quantity.