3D printed MXene/rGO hierarchical porous structure based on ultralow-concentration 2D nanomaterial inks for highly sensitive pressure sensing

Abstract

3D direct ink writing technology based on two-dimensional (2D) MXene nanomaterial inks receives attention in the field of pressure sensing for simplicity of fabrication, programmable geometry with controllable function and performance. However, it is still a huge challenge to print excellent macro-structure with ultralow-concentration MXene inks, attributed to its weak gelation ability. Herein, we construct a MXene/reduced graphene oxide (MX/rGO) architecture (0.012 g cm−3) with macroscopic (hierarchical lattice) and microscopic (porous) structure by using ultralow-concentration emulsion-based inks of MXene (5.882 mg mL−1). The introduction of octadecylamine enhances the bonding between the MXene and GO, significantly improving the gelation ability of the ink with low-concentration 2D nanomaterials. More importantly, the MX/rGO pressure sensor achieves a high sensitivity (166.957 kPa−1), wide sensing range (0.028∼100 kPa), and excellent cyclic stability (10500 cycles) due to its 3D hierarchical lattice porous structure. These sensing capabilities enable the sensor to detect various human motions, such as pulse beating, vocal cord vibration, facial expressions, different joint movements and pressure distribution. Undoubtedly, this work provides a broad development prospect for the customized flexible pressure sensors based on MXene ink 3D printing technology.