Thermoplastic Electrode Arrays in Electrochemical Paper-Based Analytical Devices

Abstract

Electrochemical paper-based analytical devices (ePADs) have garnered significant interest as an alternative to traditional benchtop methods due to their low cost and simple fabrication. Historically, ePADs have relied almost exclusively on single electrode detection, limiting potential gains in sensitivity and selectivity achievable with multiple electrodes. Herein we describe incorporation of thermoplastic electrode (TPE) arrays into flow ePADs. Quasi-steady flow was solely generated by capillary action through a fan-shaped paper device. The electrode arrays were fabricated using a simple solvent-assisted method with inexpensive materials (i.e., graphite and thermoplastic binder). These electrodes can be employed as an array of individually addressable detectors or connected as an interdigitated electrode array. The TPEs were characterized through SEM, optical profilometry and cyclic voltammetry. Chronoamperometry was used to characterize the flow-based TPE-ePADs. Trace detection of a ferrocene complex (FcTMA + ) was demonstrated through generation-collection experiments, achieving a limit of detection of 0.32 pmol. These TPE arrays containing ePADs show great promise as a rapid, sensitive, and low-cost sensor for point-of-need (PON) applications.

SECM Investigation of Carbon Composite Thermoplastic Electrodes

“…8,11 However, the signals from PCL TPEs change over time (PMMA and COC TPEs have not shown bulk signal changes over several months). 9,10 PCL is also a well-known biodegradable polymer, but its degradation time is not well controlled and takes up to two years in physiological conditions. [37][38][39] Here, we used Fc(MeOH)2 as redox mediator in SECM experiments to probe the electrochemical response of PCL TPEs at three different times: fresh, two days and two weeks after fabrication.…”

“…TPEs were fabricated as previously described. [8][9][10] Briefly, PMMA (Optix, Plaskolite), COC (8007, TOPAS, MI, USA), and PCL (ThermoMorph) were dissolved in ethyl acetate, toluene, and dichloromethane, respectively. Carbon was added in specified ratios to the thermoplastic solution by mass (1:4 thermoplastic:carbon is equivalent to 80% carbon by mass) and thoroughly mixed.…”

“…[1][2][3][4][5][6][7] There has been a recent revitalization of using carbon composite thermoplastic electrodes (TPEs) using a simple, solvent-assisted fabrication method. [8][9][10] TPEs are thermoplastic and carbon mixtures that are inexpensive and easy to prepare. They retain similar physical properties of the thermoplastic and the excellent electrochemical performance from the carbon additive.…”

Desenvolvimento de dispositivos analíticos baseados em papel usando materiais de custo baixo

“…Eletrodos metálicos apresentam condutividade superior comparado aos eletrodos desenhados em papel. No entanto, esses materiais apresentam custo relativamente alto Noviana et al (NOVIANA et al, 2019). recentemente apresentaram o uso de eletrodos termoplásticos (ETs), do inglês "thermoplastic electrodes" (TPEs), para criar os sistemas de detecção em dispositivos microfluídicos.…”

“…Em comparação com eletrodo de Pt, eletrodo de carbono vítreo e eletrodos impressos, o ET/PMMA mostrou desempenho superior ou similar para o íon ferrocianeto, o qual foi usado como sonda eletroquímica. Além disso, esse trabalho mostrou a possibilidade de melhorar a resposta eletroquímica produzida por ETs por meio do tratamento da superfície dos eletrodos com polimento e exposição a uma fonte de plasma Noviana et al (NOVIANA et al, 2019). fabricaram ETs utilizando COC e grafite.…”