An automatic sensor for measuring the optical density of microalgae culture on the Arduino Nano basis is proposed. The choice of this microcontroller is due to its wide availability, availability of free software, low cost. It is shown that in the development of such sensors a flow cell is applied, various LEDs are used as a light source. The use of the sensors given in the literature is impossible since the authors do not specify the wiring diagrams of the sensor elements, the software environment on which the algorithm of data collection is written, etc. In this work, the task is to offer a scheme for the development of an optical density sensor from standard widely available components. For example, the proposed sensor used a green led with a maximum luminosity at a wavelength of 520 nm, as a photodetector - photoresistor GL12516. During calibration of the sensor used culture of the cyanoprokaryota Spirulina platensis . The curves of the transmittance and absorption dependence on the dry biomass of S. platensis are obtained. It is shown that in the range of culture densities from 0.07 to 1.38 g DW/l the data with a high degree of accuracy (R2 = 0.99) are described by the Booger-Lambert-Ber equation. Performed testing of the sensor during the cultivation of S. platensis in a plane-parallel photobioreactors of varying thickness.
optical density sensor, Spirulina platensis, absorption coefficient, modelling, plane parallel photobioreactor
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