Electrode Design for Electrotactile Feedback With Reduced Interference to Myoelectric Signal

As the electrical stimulation (ES) may coexist with myoelectric signal (EMG) collection in a bidirectional human-machine interface, the compatibility of these two channels must be ensured at first. From the perspective of optimization, it is feasible to reduce the ES-introduced interference in the EMG signal by refining the electrode design. In this paper, a mathematical model of the electric field about ES noise propagation was first established and then verified using finite element analysis (FEA). Based on the model, a novel concentric electrode configuration with optimized electrode size used for biphasic transcutaneous electrical nerve stimulation (TENS) was proposed. The design was finally verified on both non-woven electrode and flexible printed circuit (FPC)-substrate electrode for reducing the ES noise in the myoelectric signal. This study can be used to guide the design of various TENS electrodes, whether they are monomeric or arrayed electrodes, in a typical bidirectional human-machine interface for improving the afferent/efferent signal compatibility.