Highly-sensitive expandable microsphere-based flexible pressure sensor for human-machine interaction

Abstract Flexible microstructural pressure sensors (FMPSs) have been widely used in different areas including health monitoring, human-machine interaction and electronic skin for their good reliability, easy fabrication, and highly sensitive sensing performance. Although the use of a sensing layer with microstructure improves the sensor sensitivity, it also results in limited sensitive pressure range, slow response and poor cyclic stability, which prevents the sensors from being utilized in applications requiring wide detect range, real-time response and high durability. Here, we propose an advanced micro-structured sensing layer through doping thermally expandable microspheres (EP) into the screen-printing carbon black (CB) slurry to enhance its mechanical properties. An FMPS is then developed based on this enhanced micro-structured sensing layer. Benefiting from the expanded microsphere-like microstructure, the as-prepared sensor features high sensitivity (37.16 kPa-1), fast response/recovery time (126 / 52 ms), and good mechanical stability (over 3000 cycles). In addition, a home-made and effective collision avoidance system consisting of a robotic arm, the pressure sensor, a MEGA2560 microcontroller unit (MCU) and a computer is constructed to indicate the sensor’s outstanding tactile perception characteristic, making it a promising candidate for intelligent robotic applications such as human-robot collaboration (HRC). Furthermore, we develop a pressure sensor array and demonstrate its ability to spatial pressure distribution perception. The developed microsphere-based pressure sensor and its array show great potential to be adopted in various monitoring and interactive applications such as humanoid robots, smart home, human-machine interaction, etc.