When we try to make our project real, a bioreactor is practical. We developed our hardware based on best hardware nominee NCKU Tainan 2018 team. (http://2018.igem.org/Team:NCKU_Tainan/Hardware) They have built the bioreactor that can sense the pH, CO2 concentration, and temperature. (figure1) This hardware is not fully automated. Although their smart phone application tells the user when there is a problem, someone will have to go to the bioreactor and solve it. We focused on tackling this problem.
We focused on the pH change. Our device will sense the pH change and when the pH reaches to the threshold, pH adjustment solution will be added. (Figure2) By adding this hardware to the NCKU Tainan 2018 hardware, it will be a step closer to the industrial use.
Circuit diagram is shown on figure 3. Since our servo motor did not work using 5V from Arduino, we used an adaptor that has more current. By using ceramic capacitor, electrolytic capacitor, and three-terminal regulator, electric potential of the adaptor is down to 5V. By mixing the 5V from Arduino and 5V from the adaptor with 2-bit voltage translator, servo motor can receive the signal from Arduino. The servo motor turns with the change in pH measured by the pH sensor. Not only that, but also signal from switch can turn the servo motor. Arduino code and materials we used is shown on figure 4.s