Real-Time Radiation Beam Monitoring by Flexible Perovskite Thin Film Arrays.

Real-time and in-line transversal monitoring of ionizing radiation beams is a crucial task for several applications which span from medical treatments to particle accelerators in high energy physics. Here a flexible and large area device based on 2D hybrid perovskite thin films (phenylethylammonium lead bromide), fabricated onto a thin flexible polyimide substrate, able to map the transversal beam profile of high energy radiation beams is reported. The performance of this novel tool is here compared with the one offered by standard commercial large-area technology, namely radiochromic sheets. The great potential of this class of devices is demonstrated by successfully mapping in real-time a 5 MeV proton beam at fluxes between 108 and 1010 H+ s-1 cm-2, confirming the capability to operate in a radiation-harsh environment without output signal saturation issues. The versatility and scalability of here proposed detecting system are demonstrated by the development of a multipixel array able to map in real-time a 40 kVp X-ray beam spot (dose rate 8 mGy s-1). Perovskite thin film-based detectors are thus assessed as a very promising class of thin, flexible devices for real-time, in-line, large-area, conformable, reusable, transparent, and low-cost transversal beam monitoring of different ionizing radiation.

Passive radiofrequency x-ray dosimeter tag based on flexible radiation-sensitive oxide field-effect transistor.

Distributed x-ray radiation dosimetry is crucial in diverse security areas with significant environmental and human impacts such as nuclear waste management, radiotherapy, or radioprotection devices. We present a fast, real-time dosimetry detection system based on flexible oxide thin-film transistors that show a quantitative shift in threshold voltage of up to 3.4 V/gray upon exposure to ionizing radiation. The transistors use indium-gallium-zinc-oxide as a semiconductor and a multilayer dielectric based on silicon oxide and tantalum oxide. Our measurements demonstrate that the threshold voltage shift is caused by the accumulation of positive ionization charge in the dielectric layer due to high-energy photon absorption in the high-Z dielectric. The high mobility combined with a steep subthreshold slope of the transistor allows for fast, reliable, and ultralow-power readout of the deposited radiation dose. The order-of-magnitude variation in transistor channel impedance upon exposure to radiation makes it possible to use a low-cost, passive radiofrequency identification sensor tag for its readout. In this way, we demonstrate a passive, programmable, wireless sensor that reports in real time the excess of critical radiation doses.