X-ray triggered color-tunable microgel-based interferometers for radiation dose sensing

We report the successful development of novel microgel-based interferometers for X-ray dose sensing, which can meet fast-developing and widespread applications of ionizing radiation. Poly(N-isopropylacrylamide) (pNIPAm)-based microgels are crosslinked by different molecules (i.e., N, N’-methylenebisacrylamide (BIS), N, N’-bis(acryloyl)cystamine (BAC), bis(2-acrylamidoethyl) diselenide (BASe), and bis(2-acrylamidoethyl) ditelluride) (BATe). These color-tunable photonic materials are generated by sandwiching X-ray-responsive microgels between two Au layers. The radiolysis of an aqueous solution by X-ray irradiation yields •OH radicals, leading to the cleavage of crosslinkers of pNIPAm-based microgels. The chemical reaction induces the swelling of microgels, increasing the distance between the two Au layers of the interferometers. Eventually, the optical signal of the device (i.e., reflectance spectra and color) varies with the X-ray dose, showing an ultrahigh sensitivity of 101.63 nm/Gy. For the first time, our work provides novel microgel-based interferometers for spectral and visual X-ray dose detection via the chemical–mechanical-optical signal transduction strategy.