How to Choose a Potentiostat
Posted on Fri, Aug 28, 2020 by Chris Bracher
Choosing a potentiostat can be complicated.
Modern potentiostats differ significantly from one another in terms of both functionality and price. They are all electronic devices which use feedback circuitry to control the potential across an electrochemical cell but the similarities often end there.
The main distinguishing factor between the different types of potentiostat is their intended application. It may sound obvious, but when choosing a potentiostat, the main thing to consider is what you plan to use it for. The term ‘potentiostat’ is generally used to describe lab equipment designed for the electrochemical analysis of materials, but it can also refer to portable devices designed for environmental testing or for health applications like blood testing.
Other types of potentiostat include multi-channel devices known more properly as bipotentiostats or polypoteniostats. Finally, matters are further complicated by the confusion and similarities between potentiostats and similar similar pieces of electrochemistry equipment such as galvanostats.
Potentiostats vs. Galvanostats
Galvanostats (sometimes referred to as amperostats) are similar to potentiostats in a lot of ways, and the two are often confused for one another.
Both galvanostats and potentiostats control and measure electrochemical cells by using the basic relationship between potential, current, and resistance described by Ohm’s law.
However, the two devices have very different feedback circuitry. Whereas potentiostats maintain a constant potential across a cell with a varying resistance by supplying more or less current, galvanostats maintain a constant current by varying their output potential.
Galvanostats are often used in a research setting for galvanostatic cycling. Outside of the lab, you are most likely to come across a galvanostat in the form of an everyday battery charger.
Portable and Handheld Potentiostats
Portable potentiostats are small, handheld, battery powered devices. Compared to desktop models, they are typically less powerful and are more likely to be limited to a specific function. Handheld potentiostats are most useful for testing in the field, particularly for environmental measurements where a quick quantitative result is more important than a full electrochemical analysis.
Many portable devices are designed to detect the presence and quantity of a single material in a sample. For example, they might be able to measure the amount of lead in drinking water or the amount of iron in a sample of blood. The ability to get an instant result without needing to bring the sample to the lab is clearly desirable in these situations.
USB potentiostats are the opposite of handheld potentiostats. While the latter might use an inbuilt screen or a smartphone app to display the results of a scan, USB potentiostats interface with a computer.
The pairing of a potentiostat with dedicated PC software gives the user more control over the experiment and means that the results can be analysed in more depth. The Ossila Cyclic Voltammetry software allows you to quickly and easily set up your experiment, save scan profiles so that you can easily repeat experiments, and export the results as a comma-separated value (.csv) file for use with nearly any analytical tool.
Equipment designed for voltammetric methods like cyclic voltammetry control and measure a three electrode cell using a single working electrode and channel. For some less common methods such as rotating ring-disc electrode (RRDE), a cell with more than one working electrode (and hence multiple channels) is required.
Potentiostats that control two working electrodes are known as bipotentiostats and those that can control more than two electrodes are known as polypoteniostats. In both cases, aside from the additional channels, the basic operating principles remain the same.
Multichannel potentiostats cost much more than ‘normal’ potentiostats and most people will never need the extra functionality. Choose a bipotentiostat or polypoteniostat if you intend to perform experiements that require multiple channels, but otherwise, opt for a single channel potentiostat.
Low Cost Potentiostats
Low price potentiostats are perfect for those looking for a cost effective way to equip their lab for the electrochemical analysis of materials. Others, including teaching labs, will benefit from being able to purchase multiple units without exceeding their budget.
The Ossila Potentiostat offers unparalleled value for money. When bought as a package deal with an electrochemical cell and electrodes, it comes with everything you need to start taking measurements in just a few minutes.
The Ossila Potentiostat for Cyclic Voltammetry
The Ossila Potentiostat is compact, has been designed specifically for performing cyclic voltammetry using the included PC software, and is available from just £1,300 as a standalone unit. We also offer a ‘with cell’ bundle for £1,600 that comes with an electrochemical cell, working electrode, reference electrode, and counter electrode (all available separately).
Author: Chris Bracher
Chris joined Ossila in 2016 after completing a PhD in polymer and perovskite solar cells at the University of Sheffield. During his PhD, he gained expertise in photovoltaic device fabrication and characterisation, thin-film solution processing, and the construction of automated testing systems. Formerly part of the OFET and 2D materials teams at Ossila, he now focuses on the development of new test and measurement systems, with an emphasis on software.