**3.9 Thermal cycler**

A thermal cycler or thermocycler is a device used to rapidly heat and cool the reaction mixtures and cycle them between the three PCR temperature steps [26]. Many modern thermocyclers employ the Peltier effect to achieve this temperature ramping, which is done by reversing the electric current [11]. Modern thermocyclers are also provided with heated lids to prevent condensation of reaction mixture during PCR operation. Older thermocyclers lacked this feature, and the evaporation was prevented by applying oil or wax balls on the surface of PCR mixture.
