Published on in Vol 6, No 4 (2018): Oct-Dec
                                    Preprints (earlier versions) of this paper are
                                    available at
                                    https://preprints.jmir.org/preprint/11252, first published
                                    .
                                

1 Department of Health Science, Blekinge Institute of Technology, Karlskrona, Sweden
2 Department of Mechanical Engineering, Blekinge Institute of Technology, Karlskrona, Sweden
3 Department of Technology and Aesthetics, Blekinge Institute of Technology, Karlskrona, Sweden
