Scientist putting a test tube into a centrifuge.
A centrifuge is a device that spins an object or substance at high speed. This rotational motion generates centrifugal force on the substance in the centrifuge, which pulls the particles from the center of the device. Centrifuges are used in many types of applications, including laboratory experiments and industrial manufacturing. The different types of centrifuges include preparative, hematocrit, analytical and tubular, and each has its own function.
The first commercial centrifuges, developed around 1900, were used to separate milk from cream.
Swedish inventor Gustaf de Laval is often credited with creating the first commercially viable centrifuge in 1894. His device was used to separate milk from cream. In modern times, the use of centrifuges has shifted from the dairy farm to the science lab, where they are commonly used to separate one scientific sample from another.
Preparative centrifuges are relatively large units commonly found in chemistry or biology laboratories. This type of centrifuge is used to prepare samples for experimentation. As a preparative centrifuge spins, the tested particles are separated and isolated. Scientists are able to capture specific types of particles separated for use in the laboratory.
Hematocrit centrifuges can be used to process medical blood samples.
Hematocrit centrifuges are generally smaller than preparative centrifuges and are commonly used to process medical blood samples. Unlike a preparative centrifuge, the hematocrit type is not used to isolate and capture specific particles. Instead, this device separates blood cells from blood plasma. The number of red blood cells is counted and the proportion of red blood cells in the entire sample is known as the hematocrit value. Although blood cells are counted, they are not saved individually for laboratory use.
An analytical centrifuge is typically larger than the previous two types and allows scientists to gather information about a sample while it is still inside the unit. Analytical centrifuges use optical systems such as ultraviolet light sensors to analyze particles in real time. With this type of device, scientists can observe how changes in centrifugal force affect different particles and can record data without having to stop the rotation.
Previous device types are used to process small batches of samples, but tubular centrifuges are capable of separating a continuous stream of liquids. This type of device uses an elongated rotating tube with two outlet ports. As the tube rotates, the liquids in the centrifuge are separated based on their density. This separation continues as long as fluids are present and the tube is rotating. A tubular centrifuge essentially operates as a pump capable of separating liquids and is often used to process fuel, oil or paint.