Chipless RFID Based Stretchable RF Sensor for Remote Sensing of Joint Folding Angle

Robots are increasingly being utilized in various applications, necessitating precise motion detection for effective interaction. Strain sensors enable motion detection by measuring deformation due to joint movement, with RFID-based designs offering the advantages of wireless and battery-free operation. This study presents a chipless RFID-based sensor for detecting the folding angle of a robot arm joint. The sensor was fabricated using a TPU film as the substrate and screen-printed stretchable silver ink. To evaluate its performance, the sensor was attached to a robot arm joint model, and the signal response was analyzed with respect to different folding angles. Experimental results showed that as the folding angle increased from 0° to 120°, the sensing frequency shifted from 5.63 GHz to 4.37 GHz, demonstrating a trend consistent with simulation results. These results indicate that the proposed sensor is a promising candidate for real-time, wireless motion detection in robotic applications.