Flexible Multifunctional Sensor for Robotic Perception: Integrating Material Recognition and Tactile Sensing

Flexible and compact sensors for collecting essential information from the environment are showing growing importance in robotic perception. In particular, flexible, multimodal, and low-form-factor sensors are among the major needs. In this article, a new sensor based on flexible printed circuits and flexible pressure-sensitive material was fabricated and characterized. To minimize fabrication complexity and improve reliability, the presented sensor builds on an established technology and a simple fabrication process. A layered device that can measure temperature, pressure, and surface material relative permittivity was designed, modeled, and tested. With a response time of 0.3 s, the sensor has high linearity in temperature measurement in the range of −30 °C to 120 °C. The sensor maintained its structural integrity and functional performance after undergoing a cumulative 10 h of exposure at 120 °C, demonstrating its resilience to harsh environments. In pressure measurement, the sensor monitors pressure from 0 to 65 kPa with a response time of 0.01 s, even after being overloaded approximately 50 times above the measuring range. In addition to tactile sensing, the sensor is integrated with the material recognition function based on relative permittivity measurement. This integration allows robots to recognize materials with relative permittivity between 1 and 9.3. Such functionality not only improves the adaptability of robots in various environments but also significantly augments their operational intelligence by providing crucial information about object materials, which is essential for complex task executions. Finally, the sensor was installed on a robotic gripper to simultaneously measure temperature, pressure, and material relative permittivity of surfaces. The flexible and lightweight sensor with its easy integration into robotic manipulators is promising for applications in intelligent sorting, smart factories, and intelligent prosthetics.