Patterned Ag/PI RFID Tag Integrated with Humidity Sensing by In Situ Metallization

Area of Science:

• Materials Science
• Electrical Engineering
• Sensing Technology

Background:

• Flexible electronics require cost-efficient and robust sensing solutions.
• Chipless RFID tags offer unique identification and sensing capabilities without integrated circuits.
• Wireless humidity sensing is crucial for environmental monitoring and various industrial applications.

Purpose of the Study:

• To develop a cost-efficient, flexible chipless RFID tag with integrated wireless humidity sensing.
• To investigate the fabrication of a Silver/Polyimide (Ag/PI) based RFID tag using inkjet printing and in situ metallization.
• To evaluate the humidity sensing performance, data storage capacity, and mechanical properties of the fabricated tag.

Main Methods:

• Frequency-encoding simulation using High-Frequency Structure Simulator (HFSS).
• Inkjet printing for RFID antenna mask fabrication.
• In situ metallization of polyimide (PI) film for high-quality patterned Ag antenna realization.
• Fabrication of a 2-bit chipless RFID tag with three parallel dipole resonators, one humidity-sensitive.

Main Results:

• A high-quality, flexible Ag/PI film with strong adhesion was achieved.
• The fabricated 2-bit chipless RFID tag demonstrated high humidity sensitivity.
• Excellent mechanical stability and good agreement between simulation and experimental results were observed.
• The tag successfully detected a water source, showing linear resonance frequency shift with distance.

Conclusions:

• The proposed Ag/PI chipless RFID tag offers a cost-efficient solution for flexible electronics with integrated wireless humidity sensing.
• The tag exhibits a 2-bit storage capacity, high humidity sensitivity, and excellent mechanical properties.
• The fabrication process is scalable and suitable for mass production of advanced flexible sensing devices.