1. Potentiometric
sensors
Instrumental analysis and analytical technique
01

2. Table of Contents
03
Principle
Introduction
Advantages
Disadvantages
Applications
Working

3. Sensors:
A sensor is a device which is use to detect or
sense the minor change in environment
and give some output on the other
device.
04

4. Types of Sensors:
05

5. A potentiometric sensor is a type of
electrochemical sensor that may be used to
measure potential difference of an electrode.
Potentiometric
sensor:
06

6. • The signal is measured as the potential
difference (voltage) between the
working electrodes and the reference
electrode. The working electrode's
potential must depend on the
concentration of the analyte in the gas or
solution phase.
• In the potentiometric sensor the ion-
selector electrode is coupled with the
reference electrode to complete the circuit
and the sensor measure the potential
difference between two electrode.
Principle:
07

7. The potentiometric sensor are used in analysis of glucose in blood. Glucose is
converted into ions, which is detected by ion-selective electrode. Glucose is
oxidized into gluconic acid which is further undergoes decomposition and
gives H+ ions which are detected by pH electrode.
Glucose + o2 glucose oxidase gluconic acid +H2O2.
H2O2 electrode 2H+ +O2 +2e-
+ ion measured by pH meter, a potential difference is set-up between glass
electrode and reference electrode which is sense by potentiometric sensor
which analyze the glucose level in blood.
Where we use potentiometric
sensor:
08

8.  The measuring system consists of a Ph. measuring electrode (indicating
electrode) and reference electrode.
 The potential difference between the two electrode is a function of the pH
value of the measured solution.
pH meter
09

9.  Use the potentiometer to determine the
difference b/w the potential of two electrode.
(Potentiometery)
 Two types of electrode
 Reference Electrode (fixed potential)
 Indicator Electrode (Analyte activity)
Working
10

10. Types of reference electrodes used;
 Standard Hydrogen electrode
 Ag/AgCl electrode
Reference Electrode
11

11. Potentiometric solid state gas sensors have been generally classified into three
broad groups
 Type I
 Type II
 Type III
Classification of sensors
12

12. • Type I sensors have an electrolyte containing mobile ions of the
chemical species in the gas phase that it is monitoring. The commercial
product, YSZ oxygen sensor, is an example of type I.
Type I
Type II
• Type II sensors do not have mobile ions of the chemical species to be
sensed, but an ion related to the target gas can diffuse in the solid
electrolyte to allow equilibration with the atmosphere.
13

13. Type III sensors make the electrode concept even more confusing.
With respect to the design of a solid state sensor, the auxiliary phase
looks as part of the electrode.
Type III
13

14. Potentiometric sensors are broadly used to measure position, displacement,
level, motion, pressure, airflow, and many other physical parameters. They are
also integrated into other sensors to monitor chemicals, gases, or bio cells.
Applications
15

15. Potentiometric pressure sensors
16

16. Potentiometric Airflow sensors
17

17. Potentiometric Gas Sensors
18

18. Potentiometric Biosensors
19

19.  Response is very rapid.
 Simple and low cost.
 Easy to prepare and use.
 It is not affected by catalytic poisons.
 Chemically resistant to oxidizing and reducing agents, dissolved gases, salts
,etc…
 When lithia-silica glasses are used. It can be used over the entire ranges.
Advantages
20

20.  Extremely fragile
 Minute abrasions on the surface of the tip, damages the electrode.
 It cannot be used with simple potentiometers, because of the high resistance.
 Upper limit of electrode pH is 8.
 It needs to be used freshly.
Disadvantages
21