A diesel particulate filter assembly includes a diesel particulate filter (DPF) and an electric heater that is integrally formed at an upstream end of the DPF. The electric heater includes a heating substrate and a resistive heating element. The heating substrate includes a central region and a boundary region around the central region. The resistive heating element includes a plurality of conductive portions. Adjacent ones of the conductive portions in the central region form a first spacing. Adjacent ones of the conductive portions in the boundary region form a second spacing. The second spacing is smaller than the first spacing.
STATEMENT OF GOVERNMENT RIGHTS
 This invention was produced pursuant to U.S. Government Contract No. DE-FC-04-03 AL67635 with the Department of Energy (DOE). The U.S. Government has certain rights in this invention.