Fig. 7

In vitro setup and results. a Complete in vitro setup. b Detail of half the agar cylinder, showing the position of the intramuscular electrodes and the wireless electronic circuit. The approximate location of the electrode wires connected to the battery-powered generator for EMG testing is shown in blue. c Modulating signal of the external system (Mod. signal), and output of the wireless device’s regulator (VCC), which is used to power the circuit’s electronics. A ‘high’ of the modulating signal corresponds to the delivery of HF currents. d Filtered biphasic and monophasic stimulation waveforms obtained when the wireless device rectifies the HF current immediately after the external system triggers a stimulation. The current limiters of the circuit are enabled/disabled by the control unit to obtain such waveforms. e Output of the AFE of the wireless device measured with an oscilloscope when no sinusoidal signal is present, and when there is. The AFE saturates due to the HF currents applied by the external system (see corresponding modulating signal), and recovers to have a stable state (baseline) for EMG acquisition. VCC is stable even if the HF current is applied in the form of bursts, and the circuit is at its maximum power consumption