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The need to produce high quality films at low and normal atmospheric pressure had led to the adaptation of electrochemical methods in thin film deposition. This project “Design and Construction of a two electrode potentiostat” is aimed at improving on the cost effectiveness of commercially available three electrode potentiostat, for thin film fabrication in Physics Department as the department does not have any working deposition system. The two electrode potentiostat was designed and constructed to realize an electronic module. The module was interfaced to a computer unit using a lab view software program, the results obtained indicated that the two electrode potentiostat electronic design produced the required voltage range for thin film deposition. The system though needs optimization will be of great use in the thin film preparation for research purposes.


Cover page                                                                                                                  i

Title page                                                                                                                    ii

Certification                                                                                                                iii

Dedication                                                                                                                  iv

Acknowledgement                                                                                                      v

Abstract                                                                                                                      vi

Table of content                                                                                                          vii

List of  Figure                                                                                                             xii

List of table                                                                                                                 xiv


INTRODUCTION                                                                                                     1

1.1 Background History                                                                                             1

1.2 Aims and Objectives                                                                                             2

1.3 Significance of the study                                                                                      3

1.4 Scope of the study                                                                                                            4


LITERATURE REVIEW                                                                                          5

2.1 Electrochemistry                                                                                                   5

2.2 The Potentiostat                                                                                                    6

2.2.1 The Potentiostat and History                                                                             7

2.2.2 Problems Encountered in Potentiostat                                                               8

2.3 Applications of Potentiostats                                                                                9

2.3.1 Potentiostats for use in corrosion studies                                                          9

2.3.2 Potentiostats for use in biosensor applications                                                  10

2.3.3 Potentiostats in electrodeposition of thin films                                                 11

2.3.4 Potentiostats in electrochemical energy Sources                                               12

2.4 Characteristics of Potentiostats                                                                            13

2.4.1 Control Speed                                                                                                    13

2.4.2 Accuracy                                                                                                            14

2.4.3 Current Range and Dynamics                                                                            14

2.4.4 Noise                                                                                                                  14

2.4.5 Stability                                                                                                              15

2.5 Electrodes                                                                                                             15

2.5.1 Counter Electrodes                                                                                            16

2.5.2 Reference Electrode                                                                                          16

2.5.3 Working Electrode                                                                                             17

2.6 Two-Electrode versus Three-Electrode                                                                17

2.6.1 Two- Electrode Experiment                                                                               17

2.6.2 Three Electrode Experiments                                                                             19


MATERIALS, METHODS AND TECHNIQUES                                                   21

3.1 Materials/circuit components                                                                                21

3.1.1 Diode                                                                                                                 21

3.1.2 Capacitor                                                                                                            23

3.1.3 Resistor                                                                                                              24

3.1.5 Tl074 Operational Amplifier                                                                              25

3.1.6 L7905 Negative Fixed Voltage Regulators                                                       27

3.1.7 L7805 Positive Fixed Voltage Regulators                                                         28

3.1.8 The Arduino Microcontroller                                                                             30

3.2 Electrodes                                                                                                             37

3.3.1 Working Electrode                                                                                             38

3.3.2 Reference Electrode                                                                                          38

3.4 Two Electrode Setup                                                                                            38

3.5 Description and Operating Principles Of The Two Electrode Potentiostat

Circuit Diagrams                                                                                                         39

3.5.1 Power Supply and Conditioning Circuit                                                           39

3.5.2 Signal Pre-Amplifier and Voltage Conditioning Circuit                                   40

3.5.3 Signal Post-Amplifier Output and Conditioning Circuit                                   41

3.5.4 Signal Output Processing Circuit                                                                       42

3.6 Features of The Finished Three Electrode Potentiostat                                        45


  • Software Features 46

4.2 Operating Procedures                                                                                           47

4.3 Software Development IDE Used for the Programming                                     51

4.4 Serial Port Using Visual Basic .Net For Windows Software Development         52

4.5 Checking the Virtual Serial Port Connection                                                       53

4.6 Testing Of the Potentiostat                                                                                   53

4.7 Discussion                                                                                                             54


5.1 Conclusion                                                                                                            55

5.2 Recommendation                                                                                                  55

References                                                                                                                  56


Fig. 2.1: Schematic Diagram of the 2-Electrode Set-Up                                            17

Fig. 2.2: Measured Potential Map across A Whole Cell                                             18

Fig. 2.3: Schematic diagram of the 3 electrode setup                                                 19

Fig 3.1: Diodes used and Symbol as in the Circuit                                                    21

Fig 3.2 Diode Characteristic Curve                                                                            21

Fig 3.3: Capacitors Used                                                                                            23

Fig 3.4: Resistor Used and Electronic Symbol                                                           23

Fig 3.5 TL074 Operational Amplifier                                                                         24

Fig 3.6 L7905 Negative Voltage Regulator in various packaging form                     27

Fig 3.7 Voltage Regulator Pinouts                                                                             28

Fig 3.8: The Arduino Microcontroller                                                             29

Fig 3.9: Arduino Uno Board with its various parts                                                    30

Fig 3.10: Arduino sketch IDE version 1.6.4                                                               35

Fig 3.11: The Two electrode setup                                                                             39

Fig 3.12: Power supply and conditioning circuit                                                        40

Fig 3.13: Signal Pre-amplifier and voltage conditioning circuit                                 41

Fig 3.14: Signal Post-amplifier output and conditioning circuit                                 42

Fig 3.15: Signal output processing circuit                                                                   43

Fig 3.16: Two Electrode Potentiostat circuit                                                              44

Fig 3.17: The Potentiostat Software interface when the hardware was not detected            47

Fig 4.1: No-connection detection of the Potentiostat                                                51

Fig 4.2: The Software Run a Plot in Demo Mode of operation                                 52

Fig. 4.3: software interface showing the available port                                              53


Table 3.1: Absolute Maximum Ratings of the Operational Amplifier                        26

Table 3.2: Arduino Pin functions                                                                                30



During the year 1950, metallurgist and physiochemist tried to bring some light into a fascinating electrochemical phenomenon (Bard and Faulkner, 2001) called electrochemistry.

Electrochemist discovered that if an iron electrode is dropped into diluted sulphuric acid (electrolyte), it will instantly start to corrode and if another electrode which will not corrode is inserted into the same electrolyte e.g. Platinum and iron electrode is connected to the negative pole of the current source and the platinum electrode to the positive pole of the current source, the iron dissolves will slow down or even stop depending on the voltage applied. This phenomenon was discovered already in the 17th century by Sir Humphery Davy. When the iron electrode is connected to the positive pole and the voltage increased from very low value to higher ones, the dissolution grows exponentially with increasing voltage. Above a certain current limit depending on the electrode area, the electrolytic composition and temperature, it is found that current suddenly drops to a very low value and the iron electrode stops to dissolve. This phenomenon was detected by Michael Faraday which he called ‘passivity’. Although, this phenomenon has been an object of controversy since then a better understanding of this phenomenon was possible after the invention of the potentiostat.

Although potentiostats are the foundation of modern electrochemical research, they have seen relatively little application in resource poor setting such as undergraduate laboratory courses and the developing world (Aaron et al, 2011). One reason for low penetration of potentiostat is their cost as even the least expensive potentiostat sells for more than a thousand dollars. Inexpensive electrochemical workstations could prove useful in educational laboratories, increasing access to electrochemical based analytical techniques. But with this project work, constructing a potentiostat will not even cost up to a hundred thousand naira as locally sourced material and electronic components available on the shelf will be used.



This project work is done so as to produce a cheap electrochemical analytical device which can be interfaced with dedicated computer software for real time recording and plotting ofexperimental results.



This device is a basic device used in electrochemical research which includes.

  1. Electroplating: Used in electroplating experiments.
  2. Biosensors: Used in microbial sensors for testing DNA and other proteins in the health sector.
  • It is also used in the health sector as a sensor that can be used to test for sugar level indiabetics.
  1. Energy source: Used to create electrochemical source of energy as in fuel cells super caps, batteries etc.
  2. Thin film deposition: Used for the deposition of thin films, characterizing of properties of the thin films used in solar cells.




The two-electrode potentiostat or bipotentiostat is basically an operational amplifier circuit in conjunction with an electrochemical case which comprises of the electrodes dipped into an electrolyte. It is a device which controls the potential between a pair of electrodes (working electrode and reference electrode) while measuring current flow. It is a control and measuring device.It comprises of an electric circuit which controls the potential across the cell by increasingly sensing changes in the resistance, varying according to the current supplied to the system; a higher resistance will result in a decreased current and vice-versa, in order to keep the voltage constant as described by Ohm’s law.

Most early potentiostats could function independently providing output through a physical data trace. Modern potentiostats are designed to interface with a personal computer and operate through a dedicated software package.  This automated software allows rapid shifting between experiments and experimental condition. This computer allows data to be stored and analyzed more effectively rapidly and accurately than historic methods.

The potentiostat to be designed involves electrodes in electrolyte which is activated by the following circuits or sections:

  1. Control amplifier: This amplifies the potential between the working and reference electrodes.
  2. Electrometer: This measure the potential difference between the working and reference electrodes.
  • Current -to- voltage converter: This measures the current flow.

This device is to be interfaced with operating system software on the computer so that results can be easily recorded in real time by measuring, recording and plotting of results into tables and graphs respectively. In this work it will be shown how this device can be designed, constructed and applied in electrochemical research.



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