| Abstrakt: |
An optical sensor for the dual sensing of oxygen (O 2 ) and carbon dioxide (CO 2 ) based on sensing films coated on filter paper is proposed. Ethyl cellulose (EC) doped with platinum(II) meso-tetrakis(pentafluorophenyl)porphyrin (PtTFPP) and 7-amino-4-trifluoromethyl coumarin serve as the oxygen sensing material and reference blue emission dye for the pH indicator, respectively. The CO 2 sensing layer includes the pH-sensitive fluorescent indicator 1-hydroxy-3,6,8-pyrenetrisulfonic acid trisodium salt immobilized within the EC. The O 2 - and CO 2 -sensitive materials can both be excited with a 405 nm LED, and the two emission wavelengths can be detected separately. The experimental result reveals that the optical O 2 and CO 2 sensors have sensitivities of I N 2 /I 100%O 2 =22.8 and I N 2 /I 100%CO 2 =3.6, respectively. The response times of the optical O 2 sensor were 15 s upon switching from nitrogen to O 2 and 41 s when moving from O 2 to nitrogen (N 2 ). The response times of the optical CO 2 sensor were 7 s upon switching from 100% N 2 to 100% CO 2 and 39 s when moving from 100% CO 2 to 100% N 2 . The proposed optical dual sensor can be used for the simultaneous sensing of O 2 and CO 2 concentrations in environmental applications. |
