Sacrificial 3D printing to fabricate MXene-based wearable sensors with tunable performance

Wearable sensors are becoming a vital element of newly developed smart devices for their significant prospects in health monitoring, motion detection, and human–machine interactions. Introducing a cost-effective strategy to fabricate pressure sensors with high sensitivity, compressibility, recoverability, and linearity, while also maintaining control over the structure, is a challenge in the development of scalable and high-performance wearable devices. Herein, a fused deposition modelling (FDM)-assisted dip coating is performed to fabricate highly porous pressure sensors with gyroid topologies derived from 3D-printed sacrificial molds. A layer-by-layer dip coating is proposed to obtain a uniform conductive layer over elastomer-based scaffolds using negatively and positively charged MXene nanosheets. The porous sensor based on the self-assembled MXene demonstrates a high sensitivity (9.859 kPa−1) in an extensive linearity range of up to 50 kPa, negligible hysteresis, and good stability up to 1750 cycles. Additionally, the sensor exhibits high temperature sensitivity (4.349 % °C−1) with superb linearity (up to 100 °C). The distinctive sensing and deformation mechanisms are elucidated in detail using in situ SEM and finite element analysis. By tuning the lattice structure of the sensors, the pressure sensitivities can be significantly improved to 34.43 kPa−1 and 84.47 kPa−1 within the pressure ranges of 12–34 kPa and 34–55 kPa, respectively. The gyroid-derived pressure sensor exhibits promising potential in diverse applications, including pulse rate monitoring, phonation, and motion activities. A 4 × 4 sensor array is assembled to provide real-time spatial pressure mapping. Furthermore, the wearability of the sensor can be tailored to introduce user-specific products.