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Sensors 2015, 15(9), 22234-22248;

Multi-Wavelength Based Optical Density Sensor for Autonomous Monitoring of Microalgae

Department of Agricultural and Biosystems Engineering, The University of Arizona, 1177 E. 4th Street, Shantz Building, Room 403, Tucson, AZ 85721, USA
Department of Chemical and Environmental Engineering, The University of Arizona, 1133 E James E. Rogers Way, Room 108, Tucson, AZ 85721, USA
Author to whom correspondence should be addressed.
Academic Editor: W. Rudolf Seitz
Received: 9 July 2015 / Revised: 12 August 2015 / Accepted: 25 August 2015 / Published: 2 September 2015
(This article belongs to the Special Issue Micro-Optical Sensors)
Full-Text   |   PDF [1942 KB, uploaded 2 September 2015]   |  


A multi-wavelength based optical density sensor unit was designed, developed, and evaluated to monitor microalgae growth in real time. The system consisted of five main components including: (1) laser diode modules as light sources; (2) photodiodes as detectors; (3) driver circuit; (4) flow cell; and (5) sensor housing temperature controller. The sensor unit was designed to be integrated into any microalgae culture system for both real time and non-real time optical density measurements and algae growth monitoring applications. It was shown that the sensor unit was capable of monitoring the dynamics and physiological changes of the microalgae culture in real-time. Algae biomass concentration was accurately estimated with optical density measurements at 650, 685 and 780 nm wavelengths used by the sensor unit. The sensor unit was able to monitor cell concentration as high as 1.05 g·L−1 (1.51 × 108 cells·mL−1) during the culture growth without any sample preparation for the measurements. Since high cell concentrations do not need to be diluted using the sensor unit, the system has the potential to be used in industrial microalgae cultivation systems for real time monitoring and control applications that can lead to improved resource use efficiency. View Full-Text
Keywords: optical density; multi-wavelength; microalgae; real-time monitoring and control optical density; multi-wavelength; microalgae; real-time monitoring and control

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Jia, F.; Kacira, M.; Ogden, K.L. Multi-Wavelength Based Optical Density Sensor for Autonomous Monitoring of Microalgae. Sensors 2015, 15, 22234-22248.

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