Pencil Lead as a Material for Microfluidic 3D-Electrode Assemblies

Abstract

We present an electrochemical, microfluidic system with a working electrode based on an ordered 3D array of pencil leads. The electrode array was integrated into a plexiglass/PDMS channel. We tested the setup using a simple redox probe and compared the results with computer simulations. As a proof of concept application of the device we showed that the setup can be used for determination of dopamine concentration in physiological pH and ultrasensitive, although only qualitative, detection of p-nitrophenol with a limit of detection below 1 nmol L−1. The observed limit of detection for p-nitrophenol is not only much lower than achieved with similar methods but also sufficient for evaluation of exposure to pesticides such as methyl parathion through urinalysis. This low cost setup can be fabricated without the need for clean room facilities and in the future, due to the ordered structure of the electrode could be used to better understand the process of electroanalysis and electrode functionalization. To the best of our knowledge it is the first application of pencil leads as 3D electrochemical sensor in a microfluidic channel.

Methods of Protection of Electrochemical Sensors against Biofouling in Cell Culture Applications

“…We have decided to use pencil lead electrodes, which are low cost and easy to prepare in large quantities, allowing many tests to be performed simultaneously. Besides low-cost sensing applications, pencil lead electrodes can be used as easily available, disposable sensors from high-quality graphite . Softer leads (2 or even 8B) with higher graphite to filler content should be used for electrochemical applications. , Graphite’s sp2 hybridization should also allow for efficient modification with syringaldazine.…”

Methods of protection of electrochemical sensors against biofouling in cell culture applications

“…We have decided to use pencil lead electrodes, which are low cost and easy to prepare also in large quantities allowing many tests to be performed simultaneously. Apart from low cost sensing applications pencil lead electrodes can be used as easily available, disposable sensors from high quality graphite(Witkowska Nery et al, 2018). Softer leads (2 or even 8B), with higher graphite to filler content should be used for electrochemical applications (Kariuki, 2012;Navratil et al, 2016).…”

Microfluidic devices for photo-and spectroelectrochemical applications

“…The photoelectrochemical applications also require the efficient transfer of electrons between the reactants and the electrode surface. With standard microband electrodes, a large proportion of the reactant can pass over the electrodes without interacting with them [37]. This limitation can be overcome by the development of 3D structured or flowthrough electrodes with paper-or carbon-cloth-based electrodes and microflow systems.…”