title: High-stability non-invasive autoclavable naked optical CO2 sensor.
abstract: The fabrication and characterization of a high-stability non-invasive autoclavable naked optical CO(2) sensor is described in this report. The sensor was made by using 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS) as the fluorescence dye and cetyltrimethylammonium hydroxide (CTMAOH) as the phase transfer agent (the base). A highly hydrophobic two-component silicone film was used as the polymer matrix, which overcame some of the limitations of the existing plastic type CO(2) sensors, such as dye leaching and cross-sensitivity to ions. To improve the stability of the sensor, several affecting factors were investigated. Experimental results showed that sufficient base and a small amount of water in the sensing film were critical factors that affected the stability of the sensor. Although the sensor was more stable when kept in water, the function of the sensor could recover when the sensor kept in air was transferred into water. The sensor has a lifetime of several months. The detection limit of the sensing film was about 0.03%. The average response and recovery times were 0.66 and 1.94 min, respectively. It had no cross-sensitivity to salt concentrations in the range of 0-0.2 M and to pH in the range of 5.6-8.0, so it can be used in processes with changing ion concentration and pH. It was sterilizable and could be autoclaved many times without losing its sensitivity. The applicability of the sensor in real application was successfully tested in the fermentation of Escherichia coli.
authors.affiliation: Department of Chemical and Biochemical Engineering, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
authors.forename: Xudong
authors.initials: X
authors.lastname: Ge
authors.forename: Yordan
authors.initials: Y
authors.lastname: Kostov
authors.forename: Govind
authors.initials: G
authors.lastname: Rao
mesh_terms: D001190:Arylsulfonates; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000706:statistics & numerical data; D002245:Carbon Dioxide / Q000032:analysis*; D000077286:Cetrimonium; D002593:Cetrimonium Compounds; D004867:Equipment Design; D005285:Fermentation; D005456:Fluorescent Dyes; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D055095:Optics and Photonics / Q000295:instrumentation; D015203:Reproducibility of Results; D013050:Spectrometry, Fluorescence; D014867:Water
chemical_list: D001190:Arylsulfonates; D002593:Cetrimonium Compounds; D005456:Fluorescent Dyes; D014867:Water; D002245:Carbon Dioxide; C005047:pyranine; D000077286:Cetrimonium