1. Electronic Engineering, Universitat Politecnica de Catalunya, C. Jordi Girona, 1-3, Barcelona 08034, Spain
2. Universitat de Barcelona, Martí i Franquès 1-11, Barcelona 08007, Catalunya, Spain
3. Department of Bioanalysis at Institute of Biochemistry, Vilnius University, Saulėtekio av. 7, Vilnius 10257, Lithuania