Design and Control of PM-biased Bi-stable Latching Actuator for Low-power Micropump

While the electromagnetic micropump has low-voltage driving characteristic, it requires continuous energy loss in the form of Joule heating during operations, which can be significantly problematic for battery-driven applications. This paper presents a design and control method of an energy-efficient electromagnetic bi-stable actuator for low-power micropump systems in battery-driven and low-power applications such as wearable drug delivery devices. The proposed actuator design achieves the magnetic bi-stability with the PM-biased flux, reducing the required power by providing zero-power passive latching force and by enabling reciprocating motions with only a short pulsatile current excitation. We also present in this paper the energy-efficient pulse control method using a relationship of the coil voltage and the mover velocity in order to achieve robust switching motions with minimized switching energy. The low-voltage low-power characteristic of the proposed actuator and the feasibility of the control method are experimentally validated. The measured minimum voltage and switching energy are 0.43 V and 1.88 mJ, respectively. The flow volume of the fabricated micropump prototype is measured to be 1.94 µl per latching motion.