[1] Inst Portugues Qualidade, Rua Antonio Giao 2, P-2829513 Caparica, Portugal
[2] Ist Nazl Ric Metrolog Quantum Metrol & Nanotechnol, Str Cacce 91, I-10135 Turin, Torino, Italy
[3] Ist Nazl Ric Metrolog Adv Mat, Life Sci Div, Str Cacce 91, I-10135 Turin, Torino, Italy
[4] Rhein Westfal TH Aachen, IWE2, Sommerfeldstr 24, D-52074 Aachen, Germany
[5] Res Ctr Juelich, PGI-7,Wilhelm Johnen Str, D-52425 Julich, Germany
[6] INESC Microsistemas & Nanotecnol, Rua Alves Redol 9, P-1000029 Lisbon, Portugal