1. WORKING PRINCIPLE OF DO AND pH PROBE Prepared by: Tan See Yean Yuganesh a/l Murugiah Jelita Bungin Nazzira Md Zin

3. Introduction pH measurement is readily accomplished by the combined (single unit) glass reference electrodes. pH measurement is readily accomplished by the combined (single unit) glass reference electrodes. Problem-the reading maybe referenced to the instrument ground, but may in fact interacting with a different ground through the temperature control system. Problem-the reading maybe referenced to the instrument ground, but may in fact interacting with a different ground through the temperature control system.

4. The dissolve oxygen (DO) content of the fermentation broth affecting cell growth and product formation. The dissolve oxygen (DO) content of the fermentation broth affecting cell growth and product formation. The rate of oxygen supply to the cell is often limited because the solubility of oxygen in the fermentation is low. The rate of oxygen supply to the cell is often limited because the solubility of oxygen in the fermentation is low. Measurement of dissolve oxygen under bioreactor condition is a challenging problem because low solubility of dissolve oxygen make the measurement very difficult. Measurement of dissolve oxygen under bioreactor condition is a challenging problem because low solubility of dissolve oxygen make the measurement very difficult.

5. WORKING PRINCIPLES OF pH PROBES

8. pH is an important factor in the fermentation because it has a major effect on cell growth and product formation. pH is an important factor in the fermentation because it has a major effect on cell growth and product formation. For example: For example: i) In antibiotic fermentation, even a small change in pH can cause a large fall in productivity ii) In animal cell fermentation, pH has a major effect on cell viability.

9. Formulae to determine the pH value pH= -log 10 [H + ] pH range= 1 – 14 pH value>7 = alkaline pH value < 7 = acidic pH = 7 = neutral

10. Refer figure 6.11 Refer figure 6.11 Thin glass membrane ( 0.2-0.5 mm), which reacts with water to form a hydrated gel layer. Thin glass membrane ( 0.2-0.5 mm), which reacts with water to form a hydrated gel layer. This layer exists on both sides of the membrane and is essential for the correct operation and maintenance of the electrode. This layer exists on both sides of the membrane and is essential for the correct operation and maintenance of the electrode. H + (mobile)- any difference between the ion activities on each side of the membrane will lead to a pH-dependent potential. H + (mobile)- any difference between the ion activities on each side of the membrane will lead to a pH-dependent potential.

11. Usage of pH responsive glass – restricted to the bulb-shaped element at the very end of the electrode and limits the response to the small area of the glass membrane at the electrode tips. Usage of pH responsive glass – restricted to the bulb-shaped element at the very end of the electrode and limits the response to the small area of the glass membrane at the electrode tips. Buffer solution- to maintain a constant potential. Buffer solution- to maintain a constant potential.

12. Tips for calibration the pH probes Can’t touch the membrane tips by finger because it is very fragile and high sensitivity. Can’t touch the membrane tips by finger because it is very fragile and high sensitivity. If the pH probes is taken out from the bioreactor, make sure that it is always put inside a beaker with water to ensure that it is not dry. If the pH probes is taken out from the bioreactor, make sure that it is always put inside a beaker with water to ensure that it is not dry.

13. The Working Principle Of DO Probe The Working Principle Of DO Probe

14. Dissolved oxygen (DO) is very important fermentation parameter. Dissolved oxygen (DO) is very important fermentation parameter. It affect both cell growth and production formation. It affect both cell growth and production formation. The performance of dissolved-oxygen (DO) is influenced by fluid dynamic and biological condition. The performance of dissolved-oxygen (DO) is influenced by fluid dynamic and biological condition.

18. The DO probe is made by stainless steel. The DO probe is made by stainless steel. The solution inside the cover avoid DO probe from drying. The solution inside the cover avoid DO probe from drying. At bottom of cover has membrane to detect dissolved oxygen. At bottom of cover has membrane to detect dissolved oxygen.

19. Under controlled condition, the DO probe transmits signal to amplifier. Under controlled condition, the DO probe transmits signal to amplifier. And it processed the amount of opening for each gas controller valve. And it processed the amount of opening for each gas controller valve. This principle very important in animal cell cultivation. This principle very important in animal cell cultivation.

20. Foam sensor As a measuring indicator installed in the reactor's upper lid and indicates electric conductivity. As a measuring indicator installed in the reactor's upper lid and indicates electric conductivity. Regulated by transmitting the control signal to the antifoam peristaltic pump. Regulated by transmitting the control signal to the antifoam peristaltic pump.

23. Measuring indicator antifoam added to the bioreactor Control signal WORKING PRINCIPLE OF FOAM SENSOR

24. Type of foam sensor 2 main type. Work by either: 2 main type. Work by either: 1. Detecting changes in electrical capacitance. 2. Detecting changes in electrical resistance.

25. Level sensor

27. Gas filter