A heating/cooling device for a microfluidic apparatus having a thermal insulating substrate. The device includes heating/cooling chamber for heating and/or cooling a sample disposed in the chamber; a waste heat channel for carrying away waste heat and/or waste cooling; and at least one Peltier junction having first and second opposing faces, the first face thereof facing towards said heating/cooling chamber and being in thermal communication therewith for providing either heat or cooling to the chamber in response to a flow of electrical current through the at least one Peltier junction, the second face thereof facing towards said waste heat channel and being in thermal communication therewith for either receiving heat from or dumping heat to the channel in response to a flow of electrical current through the Peltier junction.