Kapton-Based High Sensitivity RFID Humidity Sensor

In this paper, we introduce a chipless RFID humidity sensor that utilizes slow-wave resonators. The proposed sensor includes two parts: a humidity sensing part and an identification part. The humidity sensing part is based on the use of Kapton material which is characterized by a variable dielectric constant coefficient depending to the humidity level. In addition to its humidity sensing functionality, the chipless sensor contains an identification part allowing a coding capacity of 10 bits. The humidity chipless sensor showcased in this paper operates within the frequency range of 2–4 GHz, making it suitable for nondestructive testing applications. Theoretical analysis and simulation results demonstrate the sensor's high humidity sensitivity and robust coding capability.