FDM printed MXene/MnFe2O4/MWCNTs reinforced TPU composites with 3D Voronoi structure for sensor and electromagnetic shielding applications

Wearable sensors with a three-dimensional (3D) structural design and electromagnetic shielding performance are significant for the future development of wearable electronic devices. However, it remains a challenge to achieve the target goals. Herein, the thermoplastic polyurethane (TPU)/Ti 3 C 2 T x (MXene)/MnFe 2 O 4 /Multi-walled carbon nanotubes (MWCNTs) ( i.e ., TMMM) composites were innovatively designed using parametric Voronoi structure with different pore sizes and porosity upon fused deposition molding (FDM) printing. The two-dimensional (2D) MXene/zero-dimensional (0D) MnFe 2 O 4 hybrid fillers were built initially by electrostatic bonding strategy, followed by adding the one-dimensional (1D) MWCNTs as a conductive bridging agent, this way endowed the nanofillers with different dimensions uniformly dispersed to form a superb conductive network structure in the TPU matrix. When applied as pressure sensors , the TMMM composites exhibited adjustable gauge factor (GF = 1.33–3.73), extensive sensing compression range (∼89% strain with 12.03 MPa stress), good durability (6000s cyclic compression), which was very conducive to monitoring human motion, such as finger bending, wrist bending, speech recognition, etc . The sensing mechanisms were also studied using the Finite element simulations , and the variation trend of resistance change was in good agreement with the simulation results. The average electromagnetic interference shielding efficiency (EMI SE) value of the 2.1 mm-thick printed composite reached 31.2  dB , suggesting that 99.9242% of electromagnetic waves can be shielded. The proposed strategy not only provided a solution to reduce the weight of electromagnetic shielding materials , but also provided an efficient method for developing porous 3D printed parts with adjustable sensing properties at the macroscopic scale towards wearable electronic devices.