1. Institute
for Materials, Faculty of Mechanical Engineering, Ruhr-Universität Bochum, 44801 Bochum, Germany
2. ZGH, Ruhr-Universität Bochum, 44801 Bochum, Germany
3. Ecole
Polytechnique Federale de Lausanne (EPFL), Laboratoire de Microsystemes, CH-1015 Lausanne, Switzerland