Flow sensing and pumping using flexible permanent magnet beams

Abstract

A fluid flow sensor and two types of valveless pumps, based on elastic permanent magnet beams and driven by a magnetic field, are proposed and their feasibility is confirmed experimentally. In the flow sensor the beam is twisted magnetically and its bending due to flow forces is recorded as a measure of the flow velocity. In the pump of type one the magnetic beam acts as a fish fin simultaneously twisting and bending perpendicularly to the flow due to magnetic forces. In the pump of type two the magnetic beam drives a non-magnetic tail which acts as a fish tail, undulating around the steady position along the flow. The operation of the sensors and pumps is analysed analytically and verified experimentally using plastic magnets with dimensions 0.8 mm × 20 mm × (5–18) mm and a magnetization of 40 kA m −1. When driven by a meander field of ± 0.1 T, the sensor is able to sense flow velocities of 0.1–1 m s −1 and the pumps produced a volume flow up to 1.5 ml s −1. The proposed devices have simple geometry and could be fabricated in planar technology at microscale.