Technologies for wafer level fabrication of planar PEM fuel cells between I mm(2) and approximately I cm(2) were developed. These MEMS-based micro fuel cells may be potential power sources for future applications such as wireless sensor networks, chip cards or autonomous rnicrosystems. The investigations focused on pattering technologies for the fabrication of micro flow fields, design studies for integrated flow fields, material compatibility for fuel cells, patterning of membrane electrodes, serial interconnection of single cells in a planar arrangement, laminating and assembling processes. Although wafer technologies were applied, foil materials were used which allow low-cost fabrication in future production. Prototypes of self-breathing PEM fuel cells with a size of I cm x I cm and 200 mum thickness were fabricated. V/I curves were measured at a variety of ambient conditions. Stable operation was achieved at 80 mW/cm(2) at varying ambient conditions with dry hydrogen fuel. (C) 2004 Elsevier B.V. All rights reserved.