Optical sensor for dual sensing of oxygen and carbon dioxide based on sensing films coated on filter paper.
An optical sensor for the dual sensing of oxygen (O2) and carbon dioxide (CO2) 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 CO2sensing layer includes the pH-sensitive fluorescent indicator 1-hydroxy-3,6,8-pyrenetrisulfonic acid trisodium salt immobilized within the EC. The O2- and CO2-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 O2and CO2sensors have sensitivities of IN2/I100%O2=22.8 and IN2/I100%CO2=3.6, respectively. The response times of the optical O2sensor were 15 s upon switching from nitrogen to O2and 41 s when moving from O2to nitrogen (N2). The response times of the optical CO2sensor were 7 s upon switching from 100% N2to 100% CO2and 39 s when moving from 100% CO2to 100% N2. The proposed optical dual sensor can be used for the simultaneous sensing of O2and CO2concentrations in environmental applications.
Cheng-Shane
CS
Chu
Jhih-Jheng
JJ
Syu