When are actively balanced biphasic (‘Lilly’) stimulating pulses necessary in a neurological prosthesis? I Historical background; Pt resting potential;Q studies

Actively balanced (‘Lilly’) stimulating current waveforms are generally considered to give very ‘safe’ stimulation. Although this is perfectly true, the specification of the necessary waveform generators in neurological prostheses demands additional complexity, and probably additional expense and development time as well. The paper and its companion enquire whether the use of simple, passively charge-balanced stimulating pulses is equally safe, provided the stimulation parameters and circuitry are designed with appropriate care. It is concluded that, in respect of safe deliverable charge density per pulse at the electrode, release of noxious products and stimulating effectiveness, simple pulses need give no worse performance; in some circumstances they may give better.