A 3D-Printed Stretchable Planar Mesh Shape Memory Alloy Actuator with Tailorable Load-Stroke Behavior

Soft robotic and wearable systems increasingly require actuators that conform to curved surfaces and stretch with the structures they are mounted on, yet conventional shape memory alloy (SMA) form factors—wires, springs, and sheets—remain limited to one-dimensional contraction or out-of-plane bending. This paper presents the Mesh-Structured Shape Memory Alloy (MeSMA) actuator, a thin, planar, and stretchable actuator in which flat SMA wire spans form a periodic mesh clamped by 3D-printed insulating beads; the beads are fabricated by a print–pause–insert process and define the effective beam length (Le) of each span. Isotonic characterization over Le = 3–7 mm shows that the peak contraction stroke (30–81 mm) and the corresponding optimal payload (7.8–3.9 N) are well approximated by linear functions of Le over the tested range, consistent with a constant critical bending moment at the span level, establishing a single-parameter design rule for tailoring the actuator operating point. Isothermal tests show that temperature tunes the passive secant stiffness approximately threefold. Separately fabricated specimens exhibit a stroke coefficient of variation of about 1% over 30 thermal cycles with matching degradation trajectories. A tubular compression sleeve demonstrates conformal donning and spatially selective compression enabled by the planar, stretchable form factor.