1. Department of Mechanical and Manufacturing Engineering, University of Calgary, 2500 University Dr. NW., Calgary, Alberta T2N 1N4, Canada
2. Center for Bioengineering Research and Education, Biomedical Engineering Graduate Program, University of Calgary, 2500 University Dr. NW., Calgary, Alberta T2N 1N4, Canada
3. NanoScience Technology Center and Department of Physics, University of Central Florida, Orlando, Florida 32816, USA
4. Nearfield Instruments B.V., Rotterdam, Zuid-Holland 3047 AT, The Netherlands
5. Department of Mechanical Engineering, Eindhoven University of Technology, Eindhoven, Noord-Brabant 5612 AZ, The Netherlands
6. Department of Precision and Microsystems Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft, The Netherlands