A laboratory centrifuge is driven by a motor, which spins liquid samples at high speed. There are various types of centrifuges, depending on the size and the sample capacity. Like all other centrifuges, laboratory centrifuges work by the sedimentation principle, where the centripetal acceleration is used to separate substances of greater and lesser density. A microcentrifuge, also called a microfuge it is used to spin small (2 ml or less) liquid samples at high speeds (generally tens of thousands times g-force). Centrifugation of small samples is important for many biological applications, such as pelleting nucleic acids or proteins from solution, microfiltration of small aqueous samples or simply to gather those last precious drops of liquid into the bottom of the tube