Passive Wireless Sensors in Radiation Environments

This chapter delves into the use of passive wireless sensors within challenging radiation environments. In particular, the chapter focuses on passive/batteryless wireless sensors using the ultra-high frequency (UHF) radio frequency identification (RFID) technology based on the ISO/IEC 18000-6 standard of the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC) operating in the frequency range of 860-960 MHz. The chapter gives a comprehensive explanation of UHF RFID technology and various RFID sensor transponder (tag) implementations, with emphasis placed on the tag antenna’s use as a sensor. Additionally, the chapter examines the radiation environment and its impact on materials, specifically the ramifications of radiation on electronic devices. The discussion concludes by exploring radiation hardening techniques and radiation assurance testing. Lastly, the chapter explores the use of RFID sensors in radiation environments, including potential radiation effects on RFID tags and methods for protecting these tags against radiation damage. In particular, the discussion links the fundamentals of radiation effects in complementary metal-oxide-semiconductor (CMOS) circuits with the architectural characteristics and operation features of the RFID tag chip frontends, going down to the circuit block level. Although modern backscatter RFID sensor tags are not yet widely used in radiation environments, there is promising potential demonstrated by existing sensor tag prototypes. These prototypes have successfully addressed major issues, such as tight power constraints resulting from batteryless operation and harsh radiation environments caused by ionizing radiation. Signal-pattern-based sensor tag systems have proven particularly successful in areas such as wireless power transfer, setup independence, and robustness in moderate static multipath environments. Additionally, using scaled CMOS technologies for RFID tag chips and their passive operation is a promising trend that offers a certain degree of radiation hardness. This chapter’s information is also relevant to other wireless devices that rely on CMOS technology, including wireless sensors used in tough environments requiring robust performance and radiation durability. The development of wireless sensor technology to batteryless systems allows for new applications, such as proximity communication, identification, and environmental monitoring. As a result, wireless communication and sensing devices are becoming more widespread and easily accessible. The functional capabilities of batteryless wireless sensor technology are of great value, especially in harsh environments with limited human access. Regarding harsh environments, the use of ionizing radiation spans across multiple industries, including medicine, energy, and various industrial applications. Appropriate nuclear waste management remains a significant priority. X-rays remain a preferred method for medical imaging, while radiation proves useful in food processing and product quality inspection. Safety measures rely heavily on sensing and measurement equipment. The integration of passive wireless sensor technologies offers great potential for environmental sensing and communication in these radiation environments.