History of the potentiostat

Knowing the history of a device is helpful to understand certain terminologies or identify obsolete parts of a device that are still used because this is how it was always done.

Jaroslav Heyrovský developed the first polarographic instrument in 1922 for use with a dropping mercury electrode (see Figure 3.6). He received the Nobel Prize for Chemistry in 1959.

Figure 3.6 | A polarograph designed by Jaroslav Heyrovský

A more versatile instrument is the polarograph’s successor, the potentiostat. A three electrode setup became possible and most potentiostats can also be used as galvanostats, that is either the potential or the current can be controlled and the other component measured. Until the 1980’s potentiostats were bulky instruments.

The instruments were built using quite complicated analogue electronics and had a front panel with switches, multi-turn potentiometers, and one or two meters for the potential and current. At the rear panel some inputs (for additional potential control) and outputs (for potential and current) were found. These outputs could be used for an X-Y recorder. Before computers were commonly available the X-Y recorder was often a plotter. This machine was drawing the measuring results on scaled paper with a felt tip.

Figure 3.7 | Modern analogue potentiostat

For specific applications analogue instruments are still being used (Figure 3.7). Nowadays computer and analogue digital / digital analogue (AD/DA) converters are used for recording the results of a measurement, but the potentiostat itself is still a very bulky instrument. Furthermore the necessary cable connections are vulnerable to noise by acting as antennas and bad connection due to damaged cables can occur.

In the 1980’s digital potentiostats became available. These instruments were initially still quite big. The development of digital electronics was and still is progressing with high speed and the advantages of digital signals (noise reduction and fewer connections) were beneficial to the measurements.

The first digital instruments required many different digital as well as analogue components. In 2003 the EmStat, a new general purpose, low power instrument, made on a single PCB with a size of 5 cm x 3.5 cm (see Figure 3.8) became available. By far the largest component is the connector needed to make connections to the working, reference, and counter electrode.

Figure 3.8 | An EmStat digital potentiostat board by PalmSens BV

Since the measuring device itself, the potentiostat, and the means to record the measured values, a computer, shrunk the electrochemical workplace shrunk, too. Due to this development the area of research and the number of applications for electrochemistry are growing. In 2001 a battery powered potentiostat controlled by a pocket PC was introduced by PalmSens BV, at that time still named Palm Instruments BV.

In 2018, more than 15 years later, this idea of a truly mobile electrochemical device lead to the release of PStouch, an Android App to control PalmSens BV’s potentiostats. Electrochemistry has unplugged itself from the lab and is taking more and more steps into the world of point-of-care devices.

In less than a hundred years the basic equipment for electrochemical analysis was invented and shrunk from the size of a big coffer to pocket size.

 

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