Sinking sensors in solution
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To mitigate concerns of nutrient deficiencies in recirculating hydroponic systems, a novel ion- specific controller utilizing a Raspberry Pi provides continuous monitoring, and automated correction of individual ion concentrations in a liquid reservoir. For the proof of principle, a selection of four ion-specific electrodes carry voltage information regarding K+, NO3-, Ca2+, and H+ concentrations to a custom PCB where it undergoes filtering and amplification. Ion concentrations are detected in real time, and compared to a predefined concentration. If needed, an automated controller will precisely inject a liquid-ion solution into the main reservoir. This mechanism utilizes a linear slide with a stepper motor, and lead screw to cycle a syringe. Double-check valves connect this syringe with a high molarity stock ion solution, and the nutrient reservoir. Through this type of control system, ion concentrations are controlled to a grower set point.