Fabrication of magnetic shape memory micropillars using femtosecond pulsed laser

Magnetic shape memory (MSM) alloys, particularly Ni–Mn–Ga single crystals, exhibit a magnetic field induced strain (MFIS) of up to 6–12% at room temperature, making them promising candidates for high-frequency, contactless actuation in miniaturized devices. Recent advancements have explored micropillar-based actuators for applications in microfluidics, robotics, and tunable surfaces. Building on earlier femtosecond pulse width laser (FPWL) studies that fabricated MSM structures at the millimeter scale, this work extends the technique to produce fully three-dimensional, sub-millimeter Ni–Mn–Ga pillars in a single crystal specimen that retain magnetic field induced actuation. To evaluate the actuation capability of these structures, an image-based feature displacement (IBFD) analysis method was developed, comparing pre- and post-actuation images captured under different magnetic field configurations. The developed method enables automated alignment and feature displacement quantification, using Scale-Invariant Feature Transform (SIFT)-based feature tracking. Using this approach, magnetic field induced strain values of up to ∼6.2% were measured in a FPWL-fabricated micropillar. These results demonstrate that FPWL machining can produce functional MSM structures at the sub-millimeter scale while preserving both crystal structure and actuation capability, providing a viable pathway for the fabrication of MSM-based miniaturized devices.