Flexible Nafion Sensor for Ionizing Radiation Based on a Microwave Resonating System

Monitoring of high radiation levels is the primary factor in environments with high potential radioactivity levels, where it is extremely important to have a reliable measure of the dose level to avoid human exposure or damage to the electronic circuits. Therefore there is a real need for continuous, in situ monitoring of high radiation levels. Electronic solid-state MOS dosimeters are very precise but they fail at high radiation doses because their electronic circuits cannot survive the harsh radiation environment. To date, high doses of radiation can only be estimated post-factum using indirect radiation measurement mechanisms. In this contribution, a completely novel concept of a high-dose radiation detector is proposed overcoming the current limitations. The sensor is based on the emerging technology of chipless RFID, using Nafion 117 as a specific sensing material. Irradiation causes changes in the chemical structure of Nafion, which produces a shift in the resonating frequency of the sensor. Moreover, the sensing tag is extremely low-cost and is suitable for real-time wireless monitoring. The sensor has been tested with x-ray radiation up to 7 kGy, showing no sign of deterioration in its functioning and a frequency shift that is proportional to the irradiation dose.