A thermal cycler is an electronic
temperature control device used to automate the polymerase chain reaction
. The machine consists of a control system, a block which holds the reaction tubes, and a heating/cooling system. In some early models the temperature control was acheived using a fan
and an electric heater
. More recent cyclers use a Peltier
element (a compact solid-state heat pump
) which is much more reliable
and can actually cool
samples below the ambient temperature
Briefly, the polymerase chain reaction involves timed heating/cooling of the DNA and Taq DNA polymerase to achieve exponential amplification of a specific DNA sequence. The thermal cycler does this automatically. It's a far superior system to a graduate student with three water baths, a stopwatch, and three hours to kill.
The polymerase chain reaction was initially patented by Cetus Corporation, and thus anybody using it in research has to buy a licence. Fortunately, any laboratory buying a thermal cycler is also buying a licence, included in the (expensive) purchase price of the machine. Originally, cyclers were only available through Perkin-Elmer, but now many companies sell them.