A device is provided that comprises one or more fluid retainment regions each having at least one wall, and one or more loops in heat-transfer communication with the at least one wall. Each of the loops can comprise an electrical conductor that surrounds the same or a different fluid retainment region. A device is provided that comprises one or more fluid retainment regions each having particulates disposed therein. A system is provided that includes a platen adapted to hold a device including fluid retainment regions and one or more electrical conductors in heat-transfer communication with the fluid retainment regions. Methods of heating a sample are also provided.