[1] Univ Catania, Dipartimento Fis & Astron Ettore Majorana, Catania, Italy
[2] Ist & Proc Chimicofis, CNR IPCF, Messina, Italy
[3] Ist Microelettron & Microsistemi, CNR IMM UoS Catania, Catania, Italy
[4] NANO, Lab SENS CNR, Messina, Italy
[5] Univ Messina, Dipartimento Sci Chim Biol Farmaceut & Ambientali, Messina, Italy
[6] Ist Microelettron & Microsistemi, CNR IMM, Catania, Italy