Fast-response oxygen sensitive transparent coating for inner pressure ratiometric optical mapping

In this work, dual-luminophore self-referenced pressure sensitive paint (PSP) was prepared with siloxane precursors by using copolymerizable silane-functionalized carbon dots (SiCDs) as a reference probe and a newly synthesized silane-modified ruthenium complex (Ru-silane) as the sensitive probe respectively. The PSP is fully sprayable in the preparation of bi-layer thin coatings via a sol–gel process, by which a SiCD copolymerized silicone base layer was firstly constructed and subsequently covered by a Ru-silane grafted top layer. The resultant optical sensor is transparent, having a transmittance as high as 80%, besides the chemical bonding of the probes had favorably improved the stability of the luminescence properties. Based on the oxygen quenching mechanism, such transparent PSP coatings allowed efficient determination of the sudden changes of surface pressure in an inner flow channel with a time response of 1.3 ms, while the measurement can be performed from either the front side or the reverse side of the coating. Furthermore, the 2D pressure map can be quantified by calculating the intensity ratio of SiCDs to Ru-silane photoluminescence and thereby improved the accuracy of the measurement. We thus expect the transparent PSP coatings to be a useful tool in remote pressure and oxygen sensing in various fields, such as aircraft design and healthcare.