A thermal cycler for a microfluidic device includes a controller operable to provide a series of electrical signals, a heat sink, and a heating element in thermal communication with the heat sink and operable to receive the series of electrical signals from the controller. The thermal cycler also includes a thermal chuck in thermal communication with the heating element. The thermal chuck comprises a heating surface operable to make thermal contact with the microfluidic device. The heating surface is characterized by a temperature ramp rate between 2.5 degrees Celsius per second and 5.5 degrees Celsius per second and a temperature difference between a first portion of the heating surface supporting a first portion of the microfluidic device and a second portion of the heating surface supporting a second portion of the microfluidic device is less than 0.25° C.