The compressed air valve used to dry each sample after immersion is also controlled by the Arduino. This setup calls for a 24V power supply, requiring the use of a second power source. To correctly connect it to the Arduino, a MOSFET type transistor is needed; a resistor (1kΩ in this case) to limit the current flowing through the transistor, and a freewheeling diode to protect it from experiencing too high of voltage.