Simultaneous Detection of Pressure and Bending Using a Microwave Sensor with Tag and Reader Structure

Wearable technology and soft robotics have experienced significant growth in the past decade. In these applications, flexible and highly sensitive pressure and bending sensors are essential for providing feedback to control and operate devices. Despite the development of many pressure and bending sensors, the challenge remains to develop one single sensor with high sensitivity that can simultaneously measure pressure and bending, which allows for a more compact system and simplified control. In addition, wireless sensing is desirable so that the sensor and the readout system can be placed separately at convenient locations. This paper presents a new wireless microwave sensor to meet the needs. The sensor uses a resonator-based design, where pressure and bending changes are reflected as resonance frequency shifts and amplitude changes in the transmission response spectrum, respectively. This "one for two" approach allows for selective sensing and easy fabrication of the sensor, with results displayed on a cost-effective handheld device. The sensor and the reader are electromagnetically coupled without the need for physical contact offering wireless sensing. With a sensitivity of 3.39 MHz kPa1, this wireless sensor design offers a promising solution for wearable devices and soft robots due to its flexibility, small size, and low fabrication cost.