1. Department of Electronic Engineering, University of Valencia, Avda. de la Universitat, s/n, 46100-Burjassot, Spain
2. INESC Microsystems and Nanotechnologies (INESC-MN) and Institute for Nanosciences and Nanotechnologies, R. Alves Redol 9, Lisbon 1000-029, Portugal
3. INL-International Iberian Nanotechnology Laboratory, Av. Mestre José Veiga, Braga 4715-31, Portugal