Photonic polymer multilayers for colorimetric radiation sensing

•New approach for colorimetric radiation sensing using photonic polymer multilayer films.•Sensors rely on reflected structural color that depends on the degree of swelling.•Sensitivity to electron-beam irradiation in the range of ∼100 kGy.•Flexible colorimetric radiations sensors are also prepared on flexible plastic substrates.

We introduce a new approach for colorimetric sensing of ionizing radiation based on photonic polymer multilayer films. Upon immersion in a solvent, the multilayers give rise to reflected structural color in the visible region of the spectrum, with a coloration that depends on the degree of swelling of the low-index layers. Exposure to ionizing radiation leads to either preferential degradation or crosslinking of the low-index polymer, yielding a change in color in the swelled state. We demonstrate the operation of both red- and blue-shifting colorimetric sensors, with sensitivity to electron-beam irradiation in the range of ∼100 kGy, and also show that this approach allows for the preparation of sensors on flexible plastic substrates.