An experimental study on the effect of fat conductivity on voltage distribution and muscle recruitment using tissue-equivalent phantoms

The current transfer through tissues have been investigated at different electrical stimulation parameters to improve Functional Electrical Stimulation (FES). However, there are no experimental studies that investigate the effect of tissue conductivity on the recruitment. This is due to the difficulty of isolating the effect of one tissue from the others, and comparing the same tissue but with different conductivity in vivo. This study focused on the tissues parameters. Our idea is to investigate the effect of conductivity of one single tissue using tissues-equivalent phantoms setting fixedly on the skin's surface of subjects. Voltage distribution over tissues and muscle recruitment were measured in both constant current and constant voltage stimulation settings. As a result, we found that the electrical configuration containing the fat tissue with lower conductivity resulted in higher recruitment. This experimental finding agrees with the results of our simulation studies in the constant current stimulation setting.