1. Kirchhoff Institute
for Physics, Heidelberg University, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany
2. InnovationLab GmbH, Speyerer Str.
4, 69115 Heidelberg, Germany
3. Division Microrobotics and Control Engineering, University of Oldenburg, 26129 Oldenburg, Germany
4. 4th Physics Institute and Research Center
SCoPE, University of Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany