An EIS (Electrochemical Impedance Spectroscopy) Analyzer is a device that can measure how a particular substance or electrode surface responds to a potential that is constantly increased and decreased within certain predefined limits (a potential wave).
Just like a potentiostat an EIS Analyzer ensures that a potential is applied to a particular (liquid) substance. However a potentiostat is stable and the EIS Analyzer is continuously moving between a minimum and maximum.
With an EIS Analyzer, this potential wave can be increased or decreased in a sinusoidal wave at an accurately controlled frequency. For example the PalmSens4 can apply sinusoidal waves with a frequency between 1 MHz and 10 μHz.
EIS Analyzer measurements
The potential wave (Figure 1: blue) provides periodical potential differences between electrode connected to the device and the object or the (liquid) substance in contact with the electrode. This causes an electron current which also shows a wavy motion (Figure 1: green).
The EIS Analyzer measures the difference between the maximum current and the minimum current (the height of the waves), but also the time difference between the potential wave and the current wave. This allows the calculation of the electrical resistance of the liquid or object. If multiple frequencies are tested, single components and effects that are responsible for the resistance, can be identified.
EIS Analyzer applications
An EIS analyzer is mainly used for Electrochemical Impedance Spectroscopy (EIS) to investigate the electrical resistance (measured in Ohm) of substances and objects. A few examples:
- How resilient is a paint coating? In other words, how will a paint coat behave in time? Without EIS Analyzer a dye manufacturer could only reproduce the resilience of his paint layer in practice. However with an EIS analyzer it’s easy to predict the behaviour for the next ten years with a short test. Read more about this at our Palmsens Corrosion website.
- How resilient is a concrete wall, so the steel in the wall does not corrode quickly? With an EIS analyzer, you can predict in which concrete steel corrodes faster.
- How resistant is the DNA of a particular cell? DNA always appears in double strands forming a helix. It is build up in a way that the two strands of the pair match each other perfectly. If one strand is attached to an electrode, a coupling with a matching DNA strand is accompanied by a change in resistance. This can be observed with an EIS Analyzer.
Benefits of an EIS Analyzer
The big advantage of an EIS Analyzer is that it allows the user to perform a test without having to break an object. This allows a manufacturer to test any of his products before they actually leave the factory without actually using or damaging them.
A second advantage is the predictive value of tests that are made by an EIS Analyzer. An EIS Analyzer test does not take much time at all, while testing forcorrosive properties by the salt spray test takes a long time and is very pricey.
EIS Analyzer sensors
Many items can be analyzed with an EIS Analyzer. In corrosion research the corroding materials are connected directly to the EIS analyzer. This is similar in fuel cell or battery research. In analytical chemistry, a number of sensors were developed that only change their resistance in contact with specific substances.
EIS Analyzer software
An EIS Analyzer is of no use without associated software. Of course, you would like to see the measurements in a graph. The PalmSens4 includes its own easy-to-use software, which allows you to run smoothly and use the equivakent circuit fitting to get the most information out of your data. But you can also use your own current spreadsheet software for creating charts.
EIS Analyzer prices
The cost of an EIS Analyzers can be pretty high. However PalmSens managed to develop an EIS analyzer that is highly affordable, especially considering its specifications.