Ionic direct currents (DC) are employed for electrokinetic transport of biomolecules in a variety of life science technologies. The generation of these currents is problematic as the requisite electrode reactions often create pH changes, gas formation, or toxic products. Here, we address these issues by introducing a microfabricated ionic four-diode bridge rectifier, based on bipolar membranes, capable of converting ionic alternating currents (AC) to ionic DC at high efficiency (86 %). Combined with conducting polymer electrodes, this structure allows for oscillatory electrode operation in the polarizable regime, thus avoiding electrolysis. When integrated into a simple drug delivery device, 11.4 nmol of the neurotransmitter acetylcholine could be delivered using only 1.2 nmol of net electronic charge, illustrating the decoupling of the delivery capacity from the limited electrode redox capacity. Taken together, the ionic rectifier is useful in a range of iontronic and electrochemical devices to extend the lifetime of the electrodes.