A Disposable Bidirectional Micropump with Three Diaphragms Driven by a Rotating Multi-pole Magnet

Micropumps, consisting of permanent magnets and electromagnets, are used to pump fluids with precision in both directions. However, the heat generated by the electromagnets limits the biological and medical applications to which they can be applied, and the use of rare-earth magnets in the disposable part increases the cost. In this paper, we present a disposable bidirectional micropump. This has three diaphragms, each of which is pushed up by a cylindrical magnet. Each cylindrical magnet is driven by the same multipole ring magnet rotated by a micro-motor. The cylindrical magnets produce peristaltic motion to drive the fluid. The use of magnetic coupling circumvents heat being generated near the fluid channel. A retaining layer, which separates the magnets from the fluidic system, restricts the motion of the cylindrical magnets. This structure enables the pump part, which is made only from polymer, to be disposed of. A large-scale prototype, 30 mm x 30 mm x 20.8 mm in size excluding the motor, was fabricated and tested. The fabricated micropump exhibited maximum flow rates of 8.5 μl/s in the forward direction and 9 μl/s in the reverse direction, at resonant frequencies of 50 Hz and 60 Hz, respectively. The pump reached a maximum backpressure of 275 Pa in the forward direction and 330 Pa in the reverse direction, both at a resonant frequency of 50 Hz.