1. Electronics Materials and Systems Laboratory; Department of Microtechnology and Nanoscience; Chalmers University of Technology; SE-412 96 Gothenburg Sweden
2. SMIT Center; School of Mechanical Engineering and Automation; Shanghai University; 201800 Shanghai P. R. China
3. Fingerprint Cards AB; SE-411 19 Gothenburg Sweden
4. SEU-FEI Nano-Pico Center; Key Lab of MEMS of Ministry of Education; Southeast University; Nanjing 210096 P. R. China
5. SHT Smart High Tech AB; Aschebergsgatan 46 SE-411 33 Gothenburg Sweden