Build a Turbidity Sensor to Monitor and Control Microalgae Biomass Density

Log data via Yun Shield

I used turbidostat interchangeably with a system to monitor and control turbididty, like with a thermostat.

Let start with a design concept, and more details on the circuit.

The Yun Shield runs a minimal Linux distro, and it can connect to the Internet, have USB ports and SD card slot, so the data can be logged to a USB stick or a SD card. The timestamp is retrieved from the Linux system, and the data file is retrieved through an FTP program like WinSCP or FileZilla or directly from USB, SD card reader.

Design Concept
Design Concept
Simple design, harder to find the right parts
Schematics
Schematics of the turbidostat

3.2 Upload the Code
Flowchart
Flowchart of execution sequence.
A basic counting block, flushing the line, sampling, reading sensor, turn on/off the pumps and record data.
Upload Code

Here is the code hosted on GitHub. Copy and paste the code to Arduino IDE, select the right port and the chip.

Here is the data logged in microSD card.

Raw data from .csv file.
Data extracted from microSD card. A bigger voltage (and so the readoout number) represents a less obsorbed and so a smaller lower turbidity. The big pump is kicked in when the reading turbidity is lower than the set value.