Novel temperature-activated, humidity-sensitive optical sensor
Data(s) |
04/09/2016
31/12/1969
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Resumo |
A novel, colorimetric, temperature-activated humidity indicator is presented, with a colour change based on the semi-reversible aggregation of thiazine dyes (esp. methylene blue, MB) encapsulated within the polymer, hydroxypropyl cellulose (HPC). The initially purple MB/HPC film is activated by heat treatment at 370 °C for 4 s, at which point the film (with a colour associated with a highly aggregated form of MB; λmax = 530 nm) becomes blue (indicating the presence of monomeric and dimeric MB; i.e. with λmax = 665; 605 nm respectively). The blue, heat-treated MB/HPC films respond to an ambient environment with a relative humidity (RH) exceeding 70% at 21 °C within seconds, returning to their initial purple colour. This colour change is irreversible until the film is heat-treated once more. When exposed to a lower RH of up to ca. 47%, the film is stable in its blue form. In contrast, a MB/HPC film treated only at 220 °C for 15 s also turns a blue colour and responds in the same way to a RH value of ca. 70%, but it is unstable at moderate RH 37-50% values, so that it gradually returns to its purple form over a period of approximately 6 hours. The possible use of the high heat-treated MB/HPC humidity indicator in the packaging of goods that cannot tolerate high RH, such as dry foods and electronics, is discussed. |
Identificador | |
Idioma(s) |
eng |
Direitos |
info:eu-repo/semantics/embargoedAccess |
Fonte |
Mills , A , Hawthorne , D , Burns , L & Hazafy , D 2016 , ' Novel temperature-activated, humidity-sensitive optical sensor ' SENSORS AND ACTUATORS B-CHEMICAL . DOI: 10.1016/j.snb.2016.08.182 |
Tipo |
article |