Chipless 3D Microfluidic RF Sensing

Effective management of the cold chain is essential to uphold the quality and safety of products vulnerability to physical factors like temperature, humidity, pressure, etc., including perishable foods, pharmaceuticals, and vaccines. Chipless Radio Frequency Identification (RFID) sensors have become increasingly favored as a viable technology for tracking, inventory, and sensing industries due to their wireless and non-line of sight (NLOS) situations, straightforward fabrication, cost efficiency, and adaptability to challenging environmental conditions. However, there is still a need for advancements in RFID sensors to make them promise for cold chain applications. Integration of flexibility and non-volatile memory into the existing RFID technology is crucial to eliminate the reliance on external memory and constant signal monitoring, leading to reduced overall costs and an expanded range of potential applications. Investigation is also required to simplify the complex geometric fabrication processes and obtain a compact chipless RFID sensor. Moreover, detecting chipless RFID tag responses in noisy environments remains difficult due to clutter effects and multipath interference from the surroundings. Therefore, further research is needed to enhance its practical application in real-world environments.This study presents a flexible chipless RFID sensor for cold chain applications, capable of detecting physical parameters and storing data independently, eliminating the need for external memory. The sensor's structure incorporates a flexible microchannel-based liquid patch and a deformable PDMS substrate, ensuring flexibility and optimal performance. Furthermore, integrating customizable temperature threshold-detecting smart materials into the design facilitates non-volatile memory for the sensor, enabling its use in various cold chain applications for sensing multiple physical parameters. The device's geometry features a meander-shaped patch, contributing to the compact design of the chipless RFID sensor. In addition, the fabrication process utilizes additive manufacturing or 3D printing technology for the microchannel-based sensor, offering a more straightforward approach than traditional fabrication techniques. Therefore, the developed chipless RFID sensor holds considerable promise for cold chain management, enabling the wireless tracking and monitoring of products or objects while efficiently storing sensing data without needing external memory.