What Is Electrochemical Impedance Spectroscopy?
Electrochemical impedance spectroscopy (EIS) is a technique used in chemistry to measure the resistance of two substances or one substance with another substance. The method involves passing current through the sample material while measuring its resistance. If the measured value differs from zero, then it means that there are differences between the two materials. For example, if you were to measure the resistance of a battery with a resistor and found out that the resistors resistance was higher than the battery’s resistance, this would mean that there is some sort of electrical difference between them. The main advantage of using EIS over other methods such as inductive testing is that it does not require any special equipment which could affect results.
The main disadvantage of EIS is that it requires more time and effort on your part. You need to have a suitable test device and the instrumentation needs to be calibrated before use.
Also, the sensitivity of EIS depends upon how much current you want to measure.
How Does Electrochemical Impedance Spectroscopy Work?
EIS works by measuring the voltage across two electrodes separated by a small distance. When electricity flows through these electrodes, they generate different voltages when connected together. The greater the distance between two electrodes, the lower the resistance will be and the higher the voltage measured. When you plot this voltage against the separation of the two electrodes, you get a graph with a distinctive slope. This slope is entirely unique to specific materials such as biological or non-biological matter.
In biological samples, the two most common components are water and fat. Their unique electrical slopes allow us to identify their presence and measure the amounts present in the sample.
The slope can also help detect other types of materials with different compositions and densities.
While a lot of EIS devices are built for basic research, there are also more portable and affordable versions available for use in the field. Some of these are even integrated into smartphones so you can gather real-time data anywhere you want.
Why Use Electrochemical Impedance Spectroscopy?
EIS can be used to measure the electrical value of a wide range of materials such as minerals, rocks, soil, fuel, and even organic materials. It is also possible to identify and determine the different types of materials present in a mixture. EIS is also very easy to use because you do not require any complicated equipment. All you need is to connect the two electrodes and the measuring device will handle the rest.
EIS is also very good at detecting and measuring the impedance of a sample over a wide range of frequencies. This allows you to analyze the electrical response of the sample over a large range of frequencies.
Changes in the material composition are reflected in changes in the slope of this graph. This can be used to identify different types of materials with unique impedance spectra. This means the same instrument can be used to measure a wide range of samples. Finally, since this technique is non-destructive, it allows you to test multiple samples without damaging the first one.
More and more people are starting to use this technology for a wide range of applications.
What Are The Applications Of EIS?
EIS has many different uses in different fields. It is most commonly used in geology for identifying different types of minerals, rocks, and soil compositions. It can also identify types of more complex materials such as fuels, alloys, organic materials and other mixtures. EIS is used in the food industry to analyze different products for safety and quality. It is also used in clinical trials to analyze the effect of new drugs. This method is non-invasive so it is much safer than other testing methods.
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- Electrochemical impedance spectroscopy (ME Orazem, B Tribollet – New Jersey, 2008 – iopscience.iop.org)
- Electrochemical impedance spectroscopy and its applications (A Lasia – Modern aspects of electrochemistry, 2002 – Springer)
- Peer reviewed: electrochemical impedance spectroscopy for better electrochemical measurements (SM Park, JS Yoo – 2003 – ACS Publications)
- Electrochemical impedance spectroscopy as a tool for investigating underpaint corrosion (PL Bonora, F Deflorian, L Fedrizzi – Electrochimica acta, 1996 – Elsevier)
- Evaluation of organic coatings with electrochemical impedance spectroscopy (D Loveday, P Peterson, B Rodgers – JCT coatings tech, 2004 – egmont.com.pl)
- CPE analysis by local electrochemical impedance spectroscopy (JB Jorcin, ME Orazem, N Pébère, B Tribollet – Electrochimica Acta, 2006 – Elsevier)
- Electrochemical impedance spectroscopy (EIS) of corrosion processes on inhomogeneous surfaces (K Jüttner – Electrochimica Acta, 1990 – Elsevier)