Additive Manufacturing of High-Temperature Compatible Magnetic Actuators

Various MEMS devices require large displacement and large force actuation to be efficient, such as miniature pumps. Magnetic actuation delivers large displacement and large force in a compact form factor. Additive manufacturing has recently been explored as a processing toolbox for MEMS; researchers have reported additively manufactured microsystems with performance on par or better than counterparts made with standard microfabrication. In this work, miniature actuators are printed in pure Nylon 12 using the fused filament fabrication method where a thermoplastic filament is extruded from a hot nozzle to create layer by layer a solid object. The actuators have embedded magnets that are not demagnetized by the heated nozzle (@ 250 °C) while being sealed in place midstream in the printing process.
We have demonstrated the first miniature, additively manufactured, monolithic magnetic actuators compatible with high temperature (>200 °C) operation. The displacement of a 150 µm-thick, single-layer membrane actuator is characterized by various DC coil bias voltages, resulting in a maximum membrane displacement of 302 μm with 20V DC applied to the driving coil; in addition, the magnetic force is proportional to the square of the current drawn by the coil as expected from theory.