Miniaturized Electrodes in Electrochemistry: From Flexible Screen-Printed to PCB or CVD-Grown Carbon

When one sees a tiny three-electrode strip, the term “screen-printed electrode” (SPE) often comes to mind. Indeed, SPEs are among the most popular miniaturized electrodes, but not all mini electrodes are screen-printed, even if some are identical in terms of geometry and shape.

Miniaturized electrode describes a broad family of small-scale electrochemical systems, encompassing diverse materials and fabrication methods tailored to microliter volumes. Below, we highlight a few key examples of these devices, or visit our miniaturized electrode section to learn more and contact suppliers directly.

Carbon Screen-Printed Electrodes (SPEs)

Carbon-based screen-printed electrodes are perhaps the most widespread miniaturized electrodes in applied electrochemistry and biosensor development. They are made by printing conductive carbon ink onto substrates such as polymer films or ceramics. Typically, the working and counter electrodes are carbon and the reference is a printed Ag/AgCl pseudo-reference. Carbon provides a practical balance of low cost, adequate conductivity, and reasonable reproducibility, making it suitable for most standard electrochemical techniques.

The classic carbon SPE uses a rigid substrate and a basic three-electrode design without any extras. However, many variations exist. For example, there are flexible screen-printed carbon electrodes, designs with silver conductive tracks to reduce resistance, and even custom-designed SPEs tailored for specific applications.

Modified Screen-Printed Electrodes

To boost sensitivity or target specific analytes, many SPEs feature additional surface modifications. For instance:

• Activated carbon-modified electrode offers a much larger electroactive surface area
• SWCNT-modified electrode achieves higher conductivity and faster electron transfer kinetics.

These enhancements are very useful in chemical and biosensing applications, but they also introduce extra variability in terms of reproducibility and stability.

Gold-Based Miniaturized Electrodes

Biosensors often require attaching biomolecules (e.g. via thiol groups) to an electrode surface, for which gold is the preferred material. As a result, many miniaturized electrode formats employ gold. The best known examples are microfabricated thin-film gold electrodes made by lithography, which provide clean, precisely defined surfaces.

There are also gold screen-printed electrodes (using gold ink similarly to carbon SPEs) and PCB-based gold electrodes produced with standard circuit board processes. PCB-fabricated electrodes offer a cost-effective way to mass-produce disposable gold sensors for various assays.

CVD-Grown Carbon Electrodes

A more novel approach moves away from printing inks entirely: growing a carbon film via Chemical Vapor Deposition (CVD). In a CVD electrode, a thin layer of pure carbon is deposited directly on a substrate like alumina.

Because this carbon contains no binders or additives (unlike printed carbon inks), the surface is extremely clean and well-defined. Pristine CVD carbon electrodes – for example, the C3 electrode platform – provide a pure carbon interface that often yields improved baseline stability and reproducibility in measurements.

Conclusion

Choosing the right miniaturized electrode ultimately depends on the needs of the application:

• Gold electrodes are ideal when a thiol-compatible surface is required for attaching biomolecules.
• CVD-grown carbon electrodes are beneficial when a binder-free carbon surface is needed for greater stability.
• Meanwhile, classic carbon screen-printed electrodes remain the go-to choice for general use thanks to their versatility and low cost.

Future articles will explore in more detail the experimental nuances of working with these miniature electrode systems. To stay updated on new content and insights, you can subscribe to our newsletter.