1. Fraunhofer Institute for Silicon Technology (ISIT), Fraunhoferstrasse 1, D-25524 Itzehoe, Germany, eBiochip Systems GmbH, Fraunhoferstrasse 1, D-25524 Itzehoe, Germany, and Institute for Medical Microbiology and Immunology, University of Hamburg, Martinistrasse 52, D-20246 Hamburg