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What are Screen-Printed Electrodes (SPEs)?
Screen-Printed Electrodes, or SPEs, are devices to perform electrochemical measurements. These electrodes consist in a small card with an integrated circuit. This circuit is a miniaturized electrochemical cell that enables electrochemical analysis. while there are different configurations for electrochemical cells, the most common one consists in 3 electrodes:
- A Working Electrode (WE): This is the electrode where the reaction that we measure happens.
- A Counter Electrode (CE): This is the electrode that allows us to close the electrical circuit. Together with the Reference Electrode, it allows us to apply a known potential to the working electrode. The surface area of the counter electrode tends to be larger than that of the working electrode. This is to avoid any interference with the measurements on the WE.
- A Reference Electrode (RE): This electrode’s function is to act as a reference to apply or measure the potential on the WE. This electrode is made from a material that has a known and stable redox potential. While there are several materials available, the most common in SPEs is Ag/AgCl.
How are SPEs made?
As shown by their name, SPEs are fabricated via a screen-printing process.
Screen-printing is a printing technique that uses a mesh to transfer ink onto a substrate. These meshes are designed with wettable and non-weattable areas to control where the ink will go on the substrate.
During the printing process, a squegee moves accross the mesh twice:
- During the first travel, the squegee fills with ink the wettable areas of the mesh, preparing it for the printing process.
- During the second travel, the mesh is put in close contact with the substrate. Then, as the squegee presses onto the mesh as it travels, the mesh gets in touch with the substrate. As a consequence, the ink is pushed out of the mesh and onto the substrate resulting in a printed circuit.
Advantages of SPEs
While electrochemical cells are the standard to study electrochemical reactions, SPEs offer numerous advantages. Specially to develop sensors and biosensors.
- Zero maintenance: SPEs are single use. Thus, there is no maintenance associated with them.
- High reproducibility: same dimensions, same distances, every time. This makes them highly reproducible and excelent to develop sensors.
- Low cost: thinner than disk electrodes, price can be as low as 99 cents per electrode.
- Reduced size: SPEs have small featured electrodes that can be used in areas of difficult access or in portable applications.
- Reduced sample volume: due to their smaller size, SPEs can get results with just a few microliters of sample. This is ideal for applications where samples are precious, like in biosensors.
- Flexible design: due to the screen-printing process, the design can be adjusted easily.
- Easy functionalisation: SPEs can be readily functionalized with state of the art techniques to make them selective and sensitive to certain compounds.
At Macias Sensors we offer the following SPEs:
Economic inert electrode
High quality inert electrode
High quality catalitic electrode