Received: 22 June 2019
Accepted: 1 April 2020
First Online: 16 April 2020
Ethics approval and consent to participate
: The study was approved by the ethical committee of the Berlin Chamber of Physicians (Eth-28/17), and all methods were carried out in accordance with the approved study protocol. The subjects provided written informed consent before participation and consented to the publishing of their collected data.
: Written informed consent for publication was obtained from the participants involved in the study.
: JA and RH are with Axelgaard Manufacturing Co. Ltd., which is a company developing and manufacturing stimulation electrodes for FES and TENS applications. CW and TS are co-founders of SensorStim Neurotechnology GmbH, which is startup developing FES stimulation devices. All other authors declare that they have no competing interests.