Compact flexible linear stepping motors

Flexible actuators capable of bending, twisting, and stretching have garnered significant interest for applications in wearable and mobile devices. In this study, we present the development of flexible linear stepping motors (FLSMs) with moving sliders fabricated from flexible printed circuit boards as thin as 0.1 mm. The force output of these motors can be enhanced by stacking multiple sliders, and their operational stroke length is theoretically unlimited. Experimental results demonstrate a maximum speed of 500 mm/s, a step size of 25 µm, and a force constant of 743 mN/A. Notably, the proposed device achieves the highest volumetric force constant of 5.94 mN/A(mm)3 reported in the literature. The flexibility and compact design of these FLSMs make them particularly suitable for space-constrained applications, such as actuators in robotic fingers and pupillary distance adjusters in virtual reality headsets.