A micropipette is used to transfer small volumes of liquids in chemical, biological and medical laboratories. Pressing on a plunger button at the top of the micropipette will pull the liquid in, and a second press will dispense it. An adjustable micropipette uses a circular volume adjustment knob at the top of the plunger button to determine the amount of liquid that will be drawn in.
Many modern micropipettes have a digital display in the side of the barrel to indicate the volume amount set by the volume control. A disposable tip is replaced after each use by pressing an ejector button to release the used one. The disposable tips are color-coded to match the volumes they are to be used with.
Micropipettes operate by the vacuum generated by the piston-driven air displacement that occurs when the plunger is pressed. After the liquid at the tip moves into the vacuum, it can then be transported and released into another container as needed. Although micropipettes are capable of being accurate and precise, they can become less accurate as a result of user technique and temperature. The instruments' manufacturers advise users to check the calibration every 6 months. Those instruments used in the food and drug industries are required to be recalibrated every 3 months.
The first non-adjustable, or fixed, micropipette was invented by Dr. Hanns Schmitz of Germany in 1960. The biotechnology company Eppendorf obtained the rights to the patent and introduced the micropipette to the rest of the world. Henry Lardy and Warren Gilson, along with several others at the University of Wisconsin-Madison, invented the adjustable micropipette in 1972.