Interferential current stimulation for sensory communication between prosthetic hand and man

Our purpose is to clear whether the interferential current (IFC) method is useful for information transmission of a myoelectric prosthetic hand to the user. IFC stimulation is composed of two AC output waves. Previously, we demonstrated that IFC method using the two waves with different frequencies could vary the intensity of perceived stimulus. In the present study, we evaluated that the relationship between a movement of position of perceived stimulus and IFC method, using two waves with the same median frequency and a different phase. Moreover, we investigated the effects of a distance of recording electrodes from stimulating electrodes on a degree of interference of IFC with EMG signals. The movement of position of perceived stimulus was caused by the phase difference changing. IFC interfered with EMG signals. Especially, the interference of IFC with EMG of the muscle under stimulating electrodes was large. In contrast, when recording electrodes was distant from the stimulating electrodes, the interference of IFC was small. Moreover, the interference was eliminated by the low-pass filter (< 500Hz). These results support the usefulness of a combination of the IFC method with EMG recording system equipped with the low-pass filter as a sensory feedback system for myoelectric prosthetic hand