Chipless RFID Sensors for IoT Sensing and Potential Applications in Underground Mining—A Review

Chipless radio frequency identification (RFID) sensors have enormous potential for underground mining applications since this technology has the potential to meet all the requirements, such as wireless communication, maintenance-free, long lifespan, and battery-free, required to deploy in harsh underground environments. This article has analyzed existing frequency domain chipless RFID sensor technologies to understand suitability for potential applications, such as environmental condition monitoring, support system stability detection, and health monitoring of mining structures in underground mining sites. In light of the analysis, this article has presented a new classification based on sensing materials and intrinsic sensing parameters, such as effective length, coupling, conductivity, and permittivity. Furthermore, the analysis has considered accuracy, performance, and readability using 3-D electromagnetic (EM) analysis software, CST Studio Suite. Finally, based on our critical analysis and experimental simulations, this article has identified challenges that need to be addressed by future research for chipless RFID sensors in the underground mining application domain.