A Quasi-homogeneous-Integrated Flexible Proximity-Pressure Dual-Mode Sensor for Human Machine Interaction

Human-machine interaction (HMI) is being increasingly adopted across multifunctional application scenarios, and the application of flexible proximity-pressure dual-mode sensing devices can enhance the interaction efficiency and safety of HMI. However, achieving reliable sensing performance for both modes simultaneously in a single sensor unit while improving the limited durability of flexible sensors remains a significant challenge. Here, this work presents a flexible dual-mode sensor designed with a coplanar square-maze-structured capacitor, achieving a remarkable proximity sensing range of up to 250 mm. Meanwhile, by incorporating a gradient porous structure through a capacitive-piezoresistive conversion mechanism, the sensor exhibits an extended sensing range (0-200 kPa) and enhanced sensitivity (up to 6.431 kPa^-1) during the piezoresistive mode. Moreover, this work develops a quasi-homogeneous-integrated structure to address the limited durability of existing flexible sensors due to weak adhesion between the multilayered structures. All layers of the designed sensor are fabricated from either polydimethylsiloxane (PDMS) or PDMS/carbon nanotube composites, providing the sensor with robust interfaces and excellent durability. Finally, dual-mode grasping control and HMI platform experiments are conducted, demonstrating the excellent performance and robustness of the sensor. These experimental results highlight the sensor's broad application potential for intelligent robot control and HMI.