DIY nanoelectrodes: an innovative, affordable, and cleanroom-free fabrication technique

by Virginia Greco

A recent publication in 'Small’ introduces a method for manufacturing nanoelectrodes for sensing applications using readily available, low-cost materials and laboratory equipment. Performance tests have demonstrated these electrodes’ high sensitivity. This new fabrication technique, developed by researchers from the ICN2 Nanobielectronics and Biosensors Group, holds the potential to significantly influence the fields of electrochemistry and point-of-care sensing.

Nanoscale electrodes used for electrochemical sensing applications exhibit enhanced sensitivity and shorter functionalization times compared to microelectrodes, making them better suited for detecting low-concentration analytes, such as in the case of early-stage viral infections. Their fabrication, though, requires complex and lengthy methods as well as expensive equipment, in particular if they are produced in cleanrooms to improve purity and smoothness.

A team of researchers from the ICN2 Nanobioelectronics and Biosensors Group have developed a method to fabricate sensitive nanoelectrodes using inexpensive materials and tools. This technique allows for quick and easy production of custom devices which provide a sensitivity comparable to that of other nanoelectrodes on the market. This work has been recently published in an article in the journal Small, with Prof. Arben Merkoçi and Dr Andrew Piper –group leader and senior researcher, respectively– as corresponding authors. Gabriel Maroli and Vernalyn Abarintos, PhD students in Prof. Merkoçi’s group, are credited as co-first authors.

As explained in the paper, the nanoelectrodes are fabricated by depositing a thin film of metal on a substrate of a flexible plastic material, using a conventional sputter coater and a mask, acting as a stencil in which the desired shape is etched. Sputtering machines are common in many chemical laboratories and the masks can be custom made by cutting a plastic sheet with a plotter, or with aluminium. A protective layer, which can be made of Kapton tape, thin acrylic, or plastic film, is applied over the sputtered metal. The electrode is then carefully cut apart using scissors or a precision cutter.

The authors of this work ensure that the time needed to fabricate a single batch of electrodes is less than 1 hour. Furthermore, making the masks is a straightforward and quick process, taking no more than 20 minutes. This allows for easy iteratitions to vary or adjust the shape of the final electrode. Different designs can also be combined into complex 3D devices.

The scientists inspected the devices obtained with this technique by SEM imaging and put them to the test to assess their sensing performance. They functionalized some samples for the detection of a DNA sequence specific to the diagnosis of SARS-COV-2 viral infections. The outcomes of the experiments served as a proof of concept, demonstrating that the electrodes fabricated using this method exhibited sensitivity superior to that of macroelectrodes (as expected) and were comparable in performance to the best available nanoelectrodes.

The technique envisioned and developed by Prof. Merkoçi’s group enables the fabrication of sensitive nanoelectrodes without the need for cleanroom facilities or lengthy procedures. These nanoelectrodes are cost-effective, customizable in terms of shape and substrate, and can be easily produced using standard laboratory equipment and supplies. Furthermore, they demonstrate great performance even in low-concentration analyte sensing. As a result of these numerous advantages, this study is expected to make a significant impact on the fields of electrochemistry and point-of-care sensing, especially in the development of affordable sensors for early-stage disease diagnosis.

Reference article:

Gabriel Maroli, Vernalyn Abarintos, Andrew Piper, Arben Merkoçi, The cleanroom-free, cheap, and rapid fabrication of nanoelectrodes with low zM limits of detection. Small, 2023. DOI: 10.1002/smll.202302136