1. Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370 Wrocław, Poland
2. National Institute for Research and Development in Microtechnologies, Erou Iancu Nicolae 126A, 077190 Bucharest, Romania
3. LAAS, CNRS, University of Toulouse, 7 avenue du Colonel Roche, BP 54200, 31031 Toulouse CEDEX 4, France