Adaptive thermal block temperature control method and system

Aspects of the present teachings describe a method and apparatus for automatically controlling a block temperature to reduce undershooting and overshooting of the temperatures of a sample contained in the block and participating in a polymerase chain reaction (PCR). The adaptive thermal block temperature control begins when a sample temperature enters a sample window region between a preliminary setpoint temperature and a target setpoint temperature for the sample. Based on thermodynamic behavior of the sample and the predetermined phase of PCR, predicting a time period measured subsequent to the preliminary setpoint temperature when the sample will reach the target setpoint suitable for the predetermined phase of PCR. During this time period, varying the block temperature ramp rate with a series of cooling and heating changes to ensure the block temperature reaches the target setpoint temperature at approximately the same time as the sample reaches the same. Synchronizing the block temperature and sample temperature to the target setpoint temperature reduces undershooting and overshooting of the sample temperature and increases the speed and efficiency of the overall PCR process as it relates to the thermal cycling operations.