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

Abstract

This article presents a cost-efficient flexible chipless radio frequency identification (RFID) tag with wireless humidity sensing, which is fabricated by in situ metallization and inkjet printing techniques. The inkjet printing technique is applied to print the mask for RFID antenna, which is designed with frequency-encoding simulation by a high-frequency structure simulator (HFSS). A high-quality patterned Ag antenna is realized by the in situ metallization of a polyimide (PI) film, leading to strong adhesion between the Ag antenna and PI substrate. The patterned Ag antenna of the chipless RFID tag consists three parallel dipole resonators, one of which is sensitive to humidity, while the other two are utilized to encode and store data. As a result, a 2-bit chipless RFID with high humidity sensitivity based on a Ag/PI film is developed, which displays excellent flexibility and good mechanical stability. The performance of the fabricated tag shows good agreement with the simulation results. Moreover, the tag is applied to detect the water source, where the resonance frequency shows good linearity versus the distance to the water source. These results demonstrate that the proposed chipless RFID tag with humidity sensing has a 2-bit storage capacity, high humidity sensitivity, excellent mechanical properties, and long-term stability, confirming a cost-efficient preparation process for flexible electronics.

Applications of Nanomaterials in RFID Wireless Sensor Components

“…Particularly, silver nanoparticles, known for their high electrical and thermal conductivity, chemical stability, and low melting point, are widely employed [136]. Luo et al fabricated a sensing tag without an IC chip by easily replacing it with an antenna through the in-situ metallization of silver nanoparticles (Figure 6a) [104]. This sensing tag demonstrated a capacity of 2 bits without an IC chip, maintaining durability under repetitive tensile and compressive stress while proving excellent adhesion and flexibility.…”

Wireless Technologies in Flexible and Wearable Sensing: From Materials Design, System Integration to Applications

“…[63][64][65] More importantly, owing to the sensitivity to external stimuli, patterned Ag chipless RFID tags were integrated with humidity sensing to detect wet environments even at bending deformation. [41,66] By tailoring the morphologies of Ag particles, additional functions can be realized. For example, 2D Ag flakes can provide mechanical stretchability, ideal for fabricating stretchable RFID tags.…”

Fabrication of RC filters from a single printed Zn layer by reactive inkjet printing

“…Inkjet printing leads all additive manufacturing methods in the production of high quality electrical conductors [1][2][3] interconnects [4,5] planar antennas [6][7][8], RFID systems [9][10][11], sensors/transducers [12][13][14] and a host of other electronic devices that utilize metals as the principal functional material. As such, development of printing processes has principally focused on achieving metallic structures with the highest possible electrical conductivity.…”