Robust Dual Optical Sensor for pH and Dissolved Oxygen

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As part of moving our optical pH and dissolved oxygen (DO) optical chemosensors toward industrial applications, we decided to explore a many-sensors-in-one principle. It was tested if physical segregation of the optical sensor components in a single sensor polymer could remove cross-talk and quenching. It was found that a design concept with an oxygen-responsive dye in polymer nanoparticles and a pH-responsive dye in an organically modified siloxane polymer resulted in a robust pH/O2 dual optical sensor. Individually, the O2-sensitive nanoparticles, a known component for optical DO sensing, and the pH sensor are operational. Thus, it was decided to test if nanoparticles enclosed within the pH-sensitive responsive sol-gel (i) could work together if segregated and (ii) could operate with a single intensity signal that is without a reference signal; developments within industrial optical sensor technology indicate that this should be feasible. The prototype optode produced in this work was shown to have a negligible drift over 60 h, bulk diffusion-limited DO response, and independent response to pH and O2. On the individual optode, pH calibration was found to show the expected sigmoidal shape and pKa, while the complexity of the calibration function for the DO signal was significant. While the engineering of the sensor device, optics, and hardware are not robust enough to attempt generic sensor calibration, it was decided to demonstrate the design concept in simple fermentation experiments. We conclude that the dual sensor design with the physical segregation of components is viable.

Original languageEnglish
JournalACS Sensors
Issue number5
Pages (from-to)8
Number of pages1,506
Publication statusPublished - 2022

Bibliographical note

Funding Information:
The authors thank Novo Nordisk Fonden (grant NNF19OC0057136), Villum Fonden (grant 14922), Carlsbergfondet, and the University of Copenhagen for support. M.Z. and N.H. thank Lundbeckfonden (grant R346-2020-1759) and Novo Nordisk fonden (grant NNF16OC0021948). We thank Dennis Westphal Wistisen and Mikkel Knudsen Edslev from Niels Bohr Institute for the help in making the measurement container. Stefan Smedegaard Warthegau is thanked for his input to the final manuscript.

Publisher Copyright:
© 2022 American Chemical Society. All rights reserved.

    Research areas

  • composite materials, dual sensors, fermentation, microsegregation, multiple analyte sensors, optical sensors, optodes

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