Institute of Biomedical Engineering and Instrumentation, Wroclaw University of Technology, 50-370 Wroclaw, Poland. malgorzata.kotulska@pwr.wroc.pl.|Institute of Biomedical Engineering and Instrumentation, Wroclaw University of Technology, 50-370 Wroclaw, Poland. malgorzata.kotulska@pwr.wroc.pl.|Institute of Biomedical Engineering and Instrumentation, Wroclaw University of Technology, 50-370 Wroclaw, Poland. malgorzata.kotulska@pwr.wroc.pl.