Microelectrodes offer a wide range of applications in the biomedical field due to their small size and unique ability to measure electrical signals in biological systems. They can be used to measure the electrical activity of individual cells, to detect electrical potentials of neurons, and to measure local concentrations of neurotransmitters and metabolites. In addition, they have been used to deliver drugs and to image the local environment of cells. This review provides an overview of the principles and applications of microelectrodes, including their design, fabrication, and functionalization.
Microelectrodes are miniature electrodes that measure electrical signals in biological systems. They can be made from a variety of materials, including gold, platinum, and carbon nanotubes. The size of microelectrodes is usually in the range of 10−5 to 10−1 m, and they typically have an active sensing area of about 10−15 m2. The main components of microelectrodes are a conducting surface, an insulating layer, and a sensing layer. The conducting surface can be made from metals or semiconductors, and the insulating layer can be composed of various dielectrics, such as polymers, ceramics, and carbon nanotubes. The sensing layer is usually composed of a biological material, such as enzymes, antibodies, or DNA.
The fabrication of microelectrodes involves several steps, including lithography, thin-film deposition, etching, and packaging. The lithography step involves the patterning of the electrodes on a substrate, such as a silicon or glass wafer. Thin-film deposition is used to deposit the conducting and insulating layers on the patterned substrate. Etching is then used to define the shape and size of the electrode, and the final packaging step is used to protect the device from external influences.
The performance of microelectrodes is largely dependent on their functionalization. This involves the modification of the electrode surface to improve its electrical and chemical properties. For example, the surface can be modified with polymers, ligands, or antibodies to increase the sensitivity and selectivity of the electrode. Functionalization also helps to reduce the surface non-specific adsorption of biological molecules.
Microelectrodes have several applications in the biomedical field, including the detection of electrical signals from individual cells and neurons, the measurement of local concentrations of neurotransmitters and metabolites, the delivery of drugs, and the imaging of the local environment of cells. For example, microelectrodes have been used to measure the electrical activity of single cells, to detect electrical potentials of neurons, and to detect the release of neurotransmitters from synapses. They have also been used to image the local environment of cells and to deliver drugs to targeted cells.
In conclusion, microelectrodes offer a wide range of applications in the biomedical field due to their small size and unique ability to measure electrical signals in biological systems. They can be used to measure the electrical activity of individual cells, to detect electrical potentials of neurons, and to measure local concentrations of neurotransmitters and metabolites. In addition, they have been used to deliver drugs and to image the local environment of cells.
References
Hou, C. P., & Chen, T. Y. (2020). Microelectrodes: Fabrication, Functionalization, and Applications. Materials, 13(13), 3243. https://doi.org/10.3390/ma13133243
Klein, A. G., & Gray, S. K. (2020). Microelectrode Technology: A Review. Trends in Biotechnology, 38(7), 826-837. https://doi.org/10.1016/j.tibtech.2020.03.009
Völlm, B., & Höllt, V. (2018). Microelectrodes: A Tool for Neuronal Activity Detection. Frontiers in Neuroscience, 12, 661. https://doi.org/10.3389/fnins.2018.00661