1. Lecture 13 Chemical sensors

2. 2 of 17 pH sensor pH indicates how acidic or alkaline a solution is pH term translates the values of the hydrogen ion concentration Solutions with pH 7 alkaline (basic), pH = 7 is said to be neutral.

3. 3 of 17 pH sensor pH is defined as the negative logarithmic value of the Hydrogen ion (H+) concentration pH Ion Concentration (gram equivalent per liter) Type of Solution 01.0 Acid Solution - Hydrogen ions - H + 10.1 20.01 30.001 40.0001 50.00001 60.000001 70.0000001Neutral Solution 80.000001 Basic (alkaline) Solution - Hydroxide ions - OH - 90.00001 100.0001 110.001 120.01 130.1 141.0

4. 4 of 17 Examples of substances ProductpH Battery Acid0 HCl in stomach acid1 Lemon juice, vinegar2-3 Orange juice3-4 Acid rain4 Black coffee5 Urine, salvia6 Pure water7 Sea water8 Baking soda9 Ammonia solution10-11 Soapy water12 Bleach13 Oven cleaner13-14 Drain cleaner14

5. 5 of 17 pH sensor

6. 6 of 17 pH sensor - properties electrical resistance of the circuit is very high (around 400M Ω) Temperature dependent Requires regular calibration

7. 7 of 17 pH sensor

8. 8 of 17 Density - tanks

9. 9 of 17 Density - pipes

10. 10 of 17 Density – vibrating fork

11. 11 of 17 Oxygen sensor (Lambda sensor)

12. 12 of 17 Oxygen sensor (Lambda sensor)

13. 13 of 17 Blood glucose sensor

14. 14 of 17 Blood glucose sensor

15. 15 of 17 Heated alcohol sensor

16. 16 of 17 Heated alcohol sensor

17. 17 of 17 Pyroelectric infrared-detector for Gas Analysis