Screen-printed electrodes

Screen-printed electrodes (SPEs) are electrochemical measurement devices that are manufactured by printing different types of ink on plastic or ceramic substrates, allowing quick in-situ analysis with high reproducibility, sensitivity and accuracy. The composition of the different inks (carbon, silver, gold, platinum) used in the manufacture of the electrode determines its selectivity and sensitivity. This fact allows the analyst to design the most optimal device according to its purpose.
The evolution of these electrochemical cells arises from the need to reduce the size of the devices, that implies a decrease of the sample volume required in each experiment. In addition, the development of SPEs has enable the reduction of the production costs.
One of the principal advantages is the possibility of modifying the screen-printed electrodes, modifying the composition of its inks by adding different metals, enzymes, complexing agents, polymers, etc., which is useful for the preparation of multitude electrochemical analyses.
Description.
Screen printing is one of the oldest methods of reproduction. The screen-printed electrodes (SPEs) are presented as a single device in which there are three different electrodes:
The three electrodes could be printed on different types of substrates (plastic or ceramic) and could be manufactured with a great variety of inks. The most common inks are those composed of silver and carbon, however, they can be based on other metals such as platinum, gold, palladium or copper. In addition, the electrodes can be modified with enzymes, metallic nanoparticles, carbon nanotubes, polymers or complexing agents. The electrode ink composition is chosen according to the final application and the selectivity and sensitivity required for the analysis.2,5,6
The electrode manufacturing process involves the sequential deposition of different layers of conductive and/or insulating inks on the substrates of interest. The process consists of several stages:
On the other hand, as mentioned above, the most commonly used inks are silver and carbon, therefore, their printing and manufacturing characteristics should be highlighted:
Advantages and applications.
Screen-printed electrodes offer several advantages such as low cost, flexibility of their design, great reproducibility of the process and of the electrodes obtained, the possibility of manufacturing them with different materials and the wide capacity of modification of the work surface. Another advantage is the possibility of connection to a portable instrumentation allowing the in-situ determination of specific analytes. In addition, screen-printed electrodes avoid tedious cleaning processes.
Currently, they are used as a support to produce portable electrochemical biosensors for environmental analysis. Some applications are:
On the other hand, a correct manufacturing process is important to avoid low reproducibilities, to encourage mineral binders or insulating polymers that achieve a high resistance of SPE, and to use inks that do not significantly affect the kinetics of the reactions that take place. In manufacturing, surface treatments are used to remove organic contaminants from the ink. This improves their electrochemical properties by increasing the surface roughness.