Metallic pins as electrodes in low-cost (bio)electroanalytical devices

The increasing demand of fast and on-site information has grown the interest in developing simple and portable analytical devices that provide reliable responses. Electrochemical biosensors fit perfectly with these purposes because of the combination of their selectivity and ease-of-use with the simplicity, low-cost and facility of miniaturization of the electrochemical transducers. Moreover, the growing attention that has attracted the construction of do-it-yourself electronic devices in the last years has spread the use of common and mass-produced materials for the development of analytical devices. In this work, we present the use of gold-plated pins from standard connections and stainless-steel pins from needlework as electrodes in (bio)electroanalytical platforms.

In the first example, the gold-plated pins, which acted as reference (RE) and counter (CE) electrodes, were combined with a paper-based working electrode (WE). This platform showed good analytical features and it was used for developing an enzymatic glucose sensor.

The performance of stainless-steel pins as electrodes was also demonstrated constructing an enzymatic glucose sensor in which a transparency sheet was used as substrate and the pin acting as WE was modified with carbon ink. In a different design, the high versatility of the pins as electrodes allowed to insert them in a micropipette tip to obtain a system able to take the sample and perform electrochemical measurements in the same tip. This device was used for determining anionic surfactants using methylene blue as indicator.

All these innovative low-cost platforms showed good features for analytical determinations and those metallic commercial pins have demonstrated to be extremely useful for the design of interesting and simple electrochemical devices.