3D-printed magnetic porous structures with different poisson’s ratios and their mechanoelectrical conversion capabilities

Magnetic soft materials (MSMs) have a rising requirement in self-powered stress sensors and energy harvesters due to the considerable flexibility and force-driven variable magnetic strengths. Structural designs aided by additive manufacturing for MSMs can regulate their mechanoelectrical conversion capability. Here we report that porous MSMs with negative, zero and positive Poisson's ratios (NPR, ZRP and PPR, respectively) composed of Nd2Fe14B and thermoplastic urethane can be one-step fabricated by selective laser sintering. The mechanoelectrical conversion performances of MSMs with three different kinds of Poisson's ratios are investigated under vertical deformations. The results show that the lateral contraction of NPR MSMs concentrates the magnetic field distribution, leading to the maximum electrical output (7.42 mV at the strain of 40 % and compression velocity of 40 mm/s), which is 1.80 and 2.07 times that of ZPR and PPR MSMs, respectively. The experimental results have been confirmed by finite element analysis including ABAQUS/CAE and Ansys Maxwell. In addition, the electrical output of as-printed magnetoelectric devices can be adjusted by altering cells' parameters and their array permutations. In summary, the study for improving the electrical outputs of MSMs by structural design will offer a high-efficiency and promising route for self-powered sensors and other mechanoelectrical conversion devices.