What is Electrochemical Impedance Spectroscopy (EIS)? скачать в хорошем качестве

What is Electrochemical Impedance Spectroscopy (EIS)?

Lets dive into Electrochemical Impedance Spectroscopy (EIS) with Dr. Lutz Stratmann. Would you like more information about EIS: have a look at the PalmSens Knowledgebase: https://www.palmsens.com/knowledgebas.... For an overview of PalmSens potentiostats that support Electrochemical Impedance Spectroscopy, please have a look here: https://www.palmsens.com/product-select/ Transcript: Hello everyone! Impedance spectroscopy is a very complicated technique, so we would like to give you a short introduction to, you know, just get you going. First we should talk about what is impedance. Impedance is basically the same as resistance, but resistance is for DC currents, while impedance is for AC currents, so you need sine wave shaped waves to do this. How do we measure it? Well, usually we use our potentiostat to send sine wave shaped potential to our cell, and then we get a sine wave current back, and we use that for analysis. So first we use the amplitude of the potential and the amplitude of the current to calculate the impedance itself. But there's a second important parameter, which is the phase shift, and that's basically the delay between the two waves that we're measuring. So now we have measured impedance and we know how to do it, but our real system is super complicated. We have capacitive charging current, we have faradaic current, we have diffusion, we have solution resistance. How are we going to deal with all of this? Because all of this is giving us one impedance value. Well, first with scientists, we like to simplify things. We try to find simple electronic components to replace our electrochemical system. And now we want to find out what is the contribution of each of these components. Fortunately for us, the dependency on the frequency of our AC sine wave is different for the impedance of each of these components. So the trick is, we are just measuring the impedance of our system at different frequencies. And then we have no longer an impedance measurement, but we have an impedance spectroscopy, because we're measuring at multiple different frequencies. But that also means we get a lot of data. How do we present this data visually? Well, there are two popular plots, the border plot, where you just plot the logarithm of the impedance and the phase shift against the logarithm of the frequency. So you get two curves in one graph. Or the other very popular one is the Nyquist plot, where you plot the negative imaginary impedance versus the real impedance. What can you do with impedance spectroscopy? Well, you could, for example, design with this very interface sensitive technique, label-free sensors. This is an example for a DNA sensor, which was done by a friend of mine during her PhD. So she could detect the hybridization of DNA, so going from single-stranded to double-stranded DNA, without adding labels to her DNA. Other examples can be for to look at coatings. So I have coated steel here. You see that's the blue line. And then I scribed it, so I made a scratch in it. And I measured again. And I get this red curve. And you see it's a lot smaller. You had to zoom in to even see it. You can do something similar with batteries, for example, also to see the health of a battery without opening it up. If you want to use our instruments for impedance spectroscopy, that's great, because they're very compact. You can use them anywhere. They have Bluetooth, like our PalmSens4 has Bluetooth and battery integrated. Or our EmStat4S is very, very compact. You can get it into any lab to do impedance spectroscopy. So this is what we wanted to show you about impedance spectroscopy. Thanks for watching. Chapters: 0:00 Introduction 0:15 What is impedance? 0:30 How to measure impedance? 1:00 How to deal with all the components that forms the impedance? 1:52 How Electrochemical Impedance Spectroscopy helps 2:25 Two example applications for impedance spectroscopy 3:13 Which instruments support impedance spectroscopy? 3:30 Please subscribe to our YouTube channel and find us on LinkedIn   / palmsens-bv