Highly aligned porous nanocomposites with exceptional multidirectional sensing properties via heat‐assisted electrohydrodynamic printing

Abstract Flexible strain sensors have undergone significant development since their inception. Currently, most strain sensors are typically designed to detect strain in only a single direction. However, as sensor application scenarios continue to expand, challenges can arise in utilizing these uniaxial strain sensors in applications involving multiple strain directions. In this work, a carbon nanofiber (CNF)/thermoplastic polyurethane (TPU) nanocomposite sensor with a highly aligned and porous structure is fabricated via a heat‐assisted electrohydrodynamic (EHD) printing technique, where a high‐voltage electric field is applied to achieve high‐resolution filamentation and high temperature imparts a porous structure to the filament. The unique architecture of the nanocomposite promotes the formation of microcracks under strain along the alignment direction, leading to an ultra‐high strain sensitivity of 750. Under strain along the transverse direction, on the contrary, a limited sensitivity of only 12.8 is obtained because the external strain is effectively shared by the increased spacing of the aligned nanocomposite filaments. Based on the exceptional multidirectional sensing properties, we demonstrate the application of the nanocomposite sensor in detecting complex motions such as facial muscle and finger joint movements. The current work provides an effective strategy for the fabrication of anisotropic nanocomposites with precisely controlled multifunctional properties. Highlights Highly aligned porous nanocomposite was produced by heat‐assisted EHD printing. High‐voltage electric field was applied to facilitate high‐resolution filamentation. High temperature was utilized to impart a porous structure to the nanocomposite. Large sensitivity disparity was achieved along orthogonal strain directions. The multidirectional sensor is capable of detecting complex human motions.