An apparatus for performing bioelectric stimulation, the apparatus comprising: a stimulation unit; a measurement unit comprising an amplifier; first and second stimulation electrodes operable to apply electrical signals to tissue of a patient; first and second measurement electrodes operable to receive first and second measurement signals from the tissue of the patient; wherein the stimulation unit is configured to deliver a first stimulation signal to the first stimulation electrode and a second stimulation signal to the second stimulation electrode; wherein the first signal and the second signal are mirrored about a biasing voltage, the biasing voltage set in dependence of the dynamic range of the amplifier.