Journal cover Journal topic
Journal of Sensors and Sensor Systems An open-access peer-reviewed journal
J. Sens. Sens. Syst., 6, 351-359, 2017
https://doi.org/10.5194/jsss-6-351-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Regular research article
16 Oct 2017
Transmitted light pH optode for small sample volumes
Christian Rogge1, Steffen Zinn1, Paolo Prosposito2, Roberto Francini2, and Andreas H. Foitzik1 1University of Applied Science Wildau, Department of Engineering and Natural Sciences, 15745 Wildau, Germany
2University of Rome Tor Vergata, Department of Industrial Engineering and INSTM, Via del Politecnico 1, 00133 Rome, Italy
Abstract. An innovative concept of a low-cost pH optode with working volumes of less than 150 µL is presented. The pH monitoring is based on the color changing effect of pH indicators. The optode includes an RGB color sensor patch TCS34725 from Adafruit, a controllable LED and reactor slides and is addressed by a self-written LabVIEW© software. Utilizing the hue value of the HSV color model, it is possible to analyze the color change of the indicator and estimate the pH value of the analyzed samples by exploiting sigmoidal fit models. Measurements carried out with phenol red and DMEM (Dulbecco's Modified Eagle's Medium) reported a standard error of calibration in the physiologic pH range (6.5–7.5) of ±0.04 pH units.

Citation: Rogge, C., Zinn, S., Prosposito, P., Francini, R., and Foitzik, A. H.: Transmitted light pH optode for small sample volumes, J. Sens. Sens. Syst., 6, 351-359, https://doi.org/10.5194/jsss-6-351-2017, 2017.

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This work presents a cost-effective optical-based sensor for pH monitoring of sample volumes less than 150 µL. As part of a bigger project to develop a stand-alone micro bioreactor system, measurements carried out with phenol red and DMEM reported a standard error of calibration in the physiologic pH range (6.5–7.5) of pH ±0.04. Compared to other accessible optical-based sensors this reported system is a good alternative regarding the overall costs of less than EUR 50.
This work presents a cost-effective optical-based sensor for pH monitoring of sample volumes...
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