Electrochemical impedance spectroscopy (EIS) is an analysis method used for studies of surfaces, batteries, photovoltaic systems, and some life science applications. It is based on introducing a perturbation into the system being studied by means of a sine wave current or small amplitude potential. The instrument puts out an impedance diagram that provides useful data.
EIS has applications across many areas of science, including physical sciences, material science, biology, and medicine.
EIS is commonly used to study corrosion. The current is proportional to the amount of corrosion on the surface of the metal. This approach has utility in a number of areas. EIS can be used to observe corrosion resistance of dental alloys in artificial saliva, corrosion rates of biodegradable medical implants, and monitoring lithium-ion and fuel cells.
EIS has wide applicability in biology. Some examples of biological applications include:
- Studying antibody-antigen binding: Siddiqui et al interpreted an antibody-antigen binding mechanism by EIS combined with ultrananocrystalline diamond microelectrode array, showing that antibody binding on the electrode surface introduces charge transfer resistance to the system.
- Detection of tuberculosis: Mathebula et al developed a novel method to self-assemble an antigen layer on a gold electrode, then used the electrode in EIS experiments in HIV and TB positive and negative human sera to detect tuberculosis via the binding of an antibody on the electrode surface.
- Detection of HbA1c: Development of a competitive inhibition assay to detect HbA1c, a type of hemoglobin that is related to blood glucose concentration. The method could be used to develop a more accurate glucose detection system for diabetics.
- Study of electron transfer mechanisms of horseradish peroxidase: Santos et al linked charge transfer resistance to electron-hopping between the iron center of the HRP molecule and O2 and H2O2 target molecules, finding that charge transfer resistance decreases with cycling in the electrochemical system due to a slow electron transfer rate between the enzyme and O2.
Study of Tissues
EIS can be used to study the structure of tissues and differentiate between normal and cancerous tissue, and can characterize cellular changes in a quantitative manner. Information about a cell population can be collected by measuring the electrical impedance. EIS can provide impedance data over a wide frequency range, which is not available through other non-invasive techniques.
Some examples of EIS used for the study of cells and tissues include:
- Differentiation of normal and malignant prostate tissue by Halter et al: A probe measuring impedance spectra over a range of 10 kHz to 1 MHz was used to acquire spectra from five radical prostatectomy samples, finding higher conductivity and permittivity in normal prostate tissues than in malignant tissue, making these suitable parameters for tissue differentiation.
- Study of malignant and normal breast tissue: EIS was used to image breast tissue of 26 women, identifying 83 percent of ACR 4-5 lesions using visual criteria, and 67 percent using numerical criteria. EIS has potential as a technology for detection of breast malignancies.
- Determination of the state of organs: Gersing et al used EIS to detect cellular changes associated with ischemia, including accumulation of metabolic products, cell swelling caused by osmosis, and closing gap junctions.
- Application of electrochemical impedance spectroscopy (EIS) to monitor corrosion of reinforced concrete: A new approach, https://www.sciencedirect.com/science/article/pii/S0950061816301064
- Electrochemical impedance spectroscopy: an overview of bioanalytical applications, pubs.rsc.org/en/content/articlelanding/2013/ay/c3ay26476a#!divAbstract
- A quantitative study of detection mechanism of a label-free impedance biosensor using ultrananocrystalline diamond microelectrode array, https://www.ncbi.nlm.nih.gov/pubmed/22456097
- Recognition of anti-mycolic acid antibody at self-assembled mycolic acid antigens on a gold electrode: a potential impedimetric immunosensing platform for active tuberculosis, https://www.ncbi.nlm.nih.gov/pubmed/19503865
- An electrochemical impedance immunosensor based on gold nanoparticle-modified electrodes for the detection of HbA1c in human blood, onlinelibrary.wiley.com/.../elan.201200233#support-information-section
- Electrochemical impedance spectroscopy: an overview of bioanalytical applications, www.researchgate.net/.../235982768_Electrochemical_impedance_spectroscopy_An_overview_of_bioanalytical_applications
- Electrical impedance spectroscopy of the human prostate, https://www.ncbi.nlm.nih.gov/pubmed/17605363/
- Electrical impedance spectroscopy of the breast: clinical imaging results in 26 subjects, https://www.ncbi.nlm.nih.gov/pubmed/12166860/
- Impedance spectroscopy on living tissue for determination of the state of organs, www.researchgate.net/.../223047407_Impedance_spectroscopy_on_living_tissue_for_determination_of_the_state_of_organs