Construction and Electrochemical Characterization of Microelectrodes for Improved Sensitivity in Paper-Based Analytical Devices

Abstract

This work presents a simple, low cost method for creating microelectrodes for electrochemical paper-based analytical devices (ePADs). The microelectrodes were constructed by backfilling small holes made in polyester sheets using a CO2 laser etching system. To make electrical connections, the working electrodes were combined with silver screen-printed paper in a sandwich type two-electrode configuration. The devices were characterized using linear sweep voltammetry and the results are in good agreement with theoretical predictions for electrode size and shape. As a proof-of-concept, cysteine was measured using cobalt phthalocyanine as a redox mediator. The rate constant (kobs) for the chemical reaction between cysteine and the redox mediator was obtained by chronoamperometry and found to be on the order of 105 s−1 M−1. Using a microelectrode array, it was possible to reach a limit of detection of 4.8 μM for cysteine. The results show that carbon paste microelectrodes can be easily integrated with paper-based analytical devices.

Design and development of novel screen-printed microelectrode and microbiosensor arrays fabricated using ultrafast pulsed laser ablation

“…However, mass transport of redox species to macroelectrodes is by planar diffusion and is characterised by peak shaped cyclic voltammograms. Table 1 shows a compilation of the microelectrode array configurations and electrochemical performance for the electrodes manufactured on valox using the carbon ink C10903D14 and dielectric ink D2060131D1 and processed using a femtosecond laser (except geometries [17][18][19] which were to be processed using a picosecond laser). The distances between holes were calculated from the diameter of the hole and the number hemispheres apart.…”

“…Laser etching systems have been used to create holes in polyester sheets with the aim of creating microelectrode behaviour for electrochemical paper-based analytical devices (ePADs) [19]. Therefore, in the present study we wished to explore the possibility of developing a generic platform for the mass production of biosensors using the convenient combination of screenprinting and pulse laser technologies.…”

Electroanalysis moves towards paper-based printed electronics: carbon black nanomodified inkjet-printed sensor for ascorbic acid detection as a case study

“…The test zone of the electrochemical cell was then loaded with glucose oxidase, lactate oxidase, and uricase to detect glucose, lactate, and uric acid, respectively. After this pioneering work, several electrochemical paper-based sensors were developed using different paper-based substrates, such as Japanese paper [9], standard filter paper (e.g., Cordenons) [10], office paper [11], and chromatography paper (e.g., Whatman #1), [12,13]). However, these paper types are not suitable for printed electronics since the substrate should be characterized by minimized roughness and low humidity sensitivity.…”

Sustainable monitoring of Zn(II) in biological fluids using office paper

“…Although the lignin removal during pulping processes requires the use of chemicals that may pollute the environment, plastic is made by monomers derived from oil or gas, by addition of various additives, reflecting in a higher pollution when compared with paper. Whitesides' group [6][7][8] and others [9][10][11][12][13][14][15][16] reported intriguing paper-based sensing platforms capable of measuring glucose, ethanol, proteins, ions, pollutants, etc. To realize paper-based POC devices, the presence of hydrophobic/hydrophilic areas is necessary to accomplish the measurement.…”