Pencil it in: pencil drawn electrochemical sensing platforms

Abstract

Inspired by recent reports concerning the utilisation of hand drawn pencil macroelectrodes (PDEs), we report the fabrication, characterisation (physicochemical and electrochemical) and implementation (electrochemical sensing) of various PDEs drawn upon a flexible polyester substrate. Electrochemical characterisation reveals that there are no quantifiable electrochemical responses upon utilising these PDEs with an electroactive analyte that requires an electrochemical oxidation step first, therefore the PDEs have been examined towards the electroactive redox probes hexaammineruthenium(iii) chloride, potassium ferricyanide and ammonium iron(ii) sulfate. For the first time, characterisation of the number of drawn pencil layers and the grade of pencil are examined; these parameters are commonly overlooked when utilising PDEs. It is demonstrated that a PDE drawn ten times with a 6B pencil presented the most advantageous electrochemical platform, in terms of electrochemical reversibility and peak height/analytical signal. In consideration of the aforementioned limitation, analytes requiring an electrochemical reduction as the first process were solely analysed. We demonstrate the beneficial electroanalytical capabilities of these PDEs towards p-benzoquinone and the simultaneous detection of heavy metals, namely lead(ii) and cadmium(ii), all of which are explored for the first time utilising PDEs. Initially, the detection limits of this system were higher than desired for electroanalytical platforms, however upon implementation of the PDEs in a back-to-back configuration (in which two PDEs are placed back-to-back sharing a single connection to the potentiostat), the detection limits for lead(ii) and cadmium(ii) correspond to 10 μg L(-1) and 98 μg L(-1) respectively within model aqueous (0.1 M HCl) solutions.

Paper‐Based Polymer Electrodes for Bioanalysis and Electrochemistry of Neurotransmitters

“…The typical scale of the electrodes presented here is in the mm to cm range. This is in agreement with some of the devices presented in the literature, and is consistent with sizes compatible with tabletop fabrication methods …”

Pencil Graphite Electrodes: A Versatile Tool in Electroanalysis

“…In recent years, graphite pencils were used for the development of interesting electronic applications like bilayer chemiresistor [ 217 ], photoconductive PbS photodetector realized by pencil graphite electrodes drawn on stone paper acting as substrate, or a hand drawn pencil electrode for determination of lead traces in water [ 73 ], dopamine [ 74 ], or p-nitrophenol [ 30 ]. It was demonstrated that pencil drawn electrodes present the best reversibility and the highest signal if they were drawn 10 times with a 6B pencil [ 75 ]. Doped pencil leads for paper based analytical devices with chemical modified electrodes have been also reported [ 76 ].…”

Single strip solid contact ion selective electrodes on a pencil-drawn electrode substrate

“…More recently, pencil drawn electrodes (PDEs) prepared via mechanical abrasion of graphite on solid substrate have been developed and used as voltammetric sensors for the detection of metal ions. [36][37][38] They offered very water by capillary action in paper is identified as an important advantage in designing microfluidic devices. However, the same phenomenon may lead to potential instability in ISEsdiffused water is absorbed by the paper and transported towards the connectors.…”