1. Institute of Physical Chemistry
2. Albert-Ludwigs-University of Freiburg
3. 79104 Freiburg
4. Germany
5. Department of Microsystems Engineering (IMTEK)
6. Laboratory for Sensors
7. Georges-Koehler-Allee 103
8. 79110 Freiburg
9. Department of Operative Dentistry and Periodontology
10. 79106 Freiburg