title: Optical sensor based on fluorescent quenching and pulsed blue LED excitation for long-term monitoring of dissolved oxygen in NASA space bioreactors.
abstract: There is a need to monitor the concentration of dissolved oxygen (DO) present in the culture medium for NASA's space cell biology experiments, as well as in earth-based cell cultures. Continuous measurement of DO concentration in the cell culture medium in perfused bioreactors requires that the oxygen sensor provide adequate sensitivity and low toxicity to the cells, as well as maintain calibration over several weeks. Although there are a number of sensors for dissolved oxygen on the market and under development elsewhere, very few meet these stringent conditions. An in-house optical oxygen sensor (HOXY) based on dynamic fluorescent quenching of Tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) chloride and a pulsed blue LED light source was developed in our laboratory to address these requirements. The sensing element consisted of the fluorescent dye embedded in a silicone matrix and coated onto a glass capillary. Photobleaching was minimized by a pulsed LED light source. The total noise in the sensor output is 2% and the sensor dynamic range is 0 to 200 mm Hg. The resolution of the sensor is 0.1 mm Hg at 50 mm Hg, and 0.25 mm Hg at 130 mm Hg, while the accuracy is 5%. The LED-based oxygen sensor exhibited stable performance and low drift, making it compatible for space-flight bioreactor systems.
authors.affiliation: Wyle Life Sciences, 1290 Hercules Drive, Suite 120, Mail Stop BT-37, Houston, Texas 77058, USA.
authors.forename: Frank G
authors.initials: FG
authors.lastname: Gao
authors.forename: James M
authors.initials: JM
authors.lastname: Fay
authors.forename: Grace
authors.initials: G
authors.lastname: Mathew
authors.forename: Antony S
authors.initials: AS
authors.lastname: Jeevarajan
authors.forename: Melody M
authors.initials: MM
authors.lastname: Anderson
mesh_terms: D019149:Bioreactors; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D018929:Cell Culture Techniques / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008029:Lighting; D008991:Monitoring, Physiologic / Q000295:instrumentation / Q000379:methods; D055095:Optics and Photonics / Q000295:instrumentation*; D010100:Oxygen / Q000032:analysis*; D015203:Reproducibility of Results; D012666:Semiconductors; D012680:Sensitivity and Specificity; D013026:Space Flight / Q000295:instrumentation*; D013050:Spectrometry, Fluorescence / Q000295:instrumentation* / Q000379:methods; D013997:Time Factors; D014481:United States; D018557:United States National Aeronautics and Space Administration
chemical_list: D010100:Oxygen