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The detection of oxygen (O-2) by optical sensors is of growing importance, for example, in biology, life science, environmental science, and aerodynamics, where the composition of gases is crucial for many applications. Purely organic optical O-2 sensors are very attractive for monitoring food deterioration, biosensing, and biomonitoring, as they can provide continuous, reversible, and nondestructive O-2 sensing. However, purely organic optical reversible O-2 sensors that can work with a broad O-2 concentration range and that have robust reversibility are yet to be realized. We hereby developed a purely organic optical O-2 sensor by embedding polyimide-based photoemitters within a poly(vinyl alcohol) (PVA) matrix. The photoemitters are synthesized through one-pot hydrothermal reactions. They have a lifetime of room temperature phosphorescence (RTP) of up to a few microseconds (mu s) when they are embedded into the polymer matrix. Our results demonstrate that the photoemitters have higher sensitivity and broader sensing range to O-2 if they are synthesized with longer reaction times because they possess a more rigid polyimide structure. The O-2 sensor with such optimized photoemitters embedded in the polymer matrix exhibits continuous and broad-range O-2 sensing in the range of 0-16% O-2. The Stern-Volmer quenching constant (Ksv) was calculated to be 0.2351 kPa(-1) for the linear response range of 0-4% O-2. Moreover, the O-2 sensor can be repetitively used at least 10 times in the linear range (04% O-2) or beyond the linear range (up to 21% O-2). The metal-free, purely organic sensors that enable the continuous and repetitive detection of O-2 within a relevant O-2 sensing range are appealing especially for monitoring packaged food, biomonitoring, and biosensing.
Véronique Michaud, Jacobus Gerardus Rudolph Staal, Baris Çaglar, Helena Luisa Teixido Pedarros
Alessandro Mapelli, Arnaud Bertsch, Fabrizio Carbone, Veronica Leccese
Véronique Michaud, Vincent Werlen, Christian Rytka