Pulse controlled microfluidic actuators with ultra low energy consumption

This paper presents the modelling, simulation, implementation and performance analysis of a novel electropermanent magnet based, bistable wireless microactuator for microvalves with milli Joule level energy consumption. The microactuator is powered wirelessly through inductive power transfer with energy buffered in a supercapacitor bank. Two millimeter sized rods of semi hard and hard magnetic materials are placed side by side with a current carrying coil around them. A 120 μs pulse of 15 V, 2.5 A is applied to the coil, which creates or eliminates the externally available magnetic field. The plunger is either attracted or repelled by this magnetic field to open or close the valve respectively. The theoretical analysis and modelling aligns well with the experimental results. The microactuator consume as little as 0.97-2.5 mJ of energy per actuation with no energy consumed between actuations. The actuation pulse width needs to be between 44 and 150 μs. The actuator is capable of delivering large deflections in the range of 0.3-2.5 mm, which is much greater than any of the state-of-the-art valves. The maximum holding force of the actuator is 220 mN and the attraction force varies between 9.8-98 mN. Energy consumption per actuation, actuation speed and deflection of the novel actuator are much better than any state-of-the-art microvalves, with the added advantages of wireless power and control. The momentary peak power requirement of 40 W is met by the supercapacitor energy buffer which stores 90 J per charge cycle, sourcing 37500 actuations. The energy efficiency and flexibility of this novel actuator can revolutionize the microactuator industry.