Abstract
Contamination of drinking water by hazardous agents is becoming a serious global threat, so it is necessary to develop more efficient sensing technologies for applications in liquid media. The limited working lifetime of electrochemical biosensors, especially when measurements are made continuously in liquid media, remains an unsolved challenge. We studied the effect of PEDOT:PSS surface area on platinum microelectrodes with respect to electrode ability to conduct reversible ion-to-electron transduction in liquid media. Electropolymerization of 3,4-ethylenedioxythiophene:poly(styrene sulfonate) EDOT:PSS to poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) was conducted on microplatinum electrodes 5 and 10 mm long using a galvanostatic mode. Cyclic voltammetry was used to determine capacitive peak current; higher peak current indicates higher redox capacitance. Field-emisison scanning-electron microscopy was used to study the surface morphology of the PEDOT:PSS transucer layer after measurement in liquid media. The anodic capacitive peak currents did not differ significantly between the two electrodes at day one (~0.20 mA); however, peak current decreased by ~ 20% and ~ 80% at day six for 10- and-5 mm electrode lengths, respectively. The results imply that PEDOT:PSS surface area plays a role in transduction of PEDOT:PSS in aqueous media.
Highlights
The ability to evaluate food quality and freshness, as well as water quality, requires sensors that can operate in aqueous media
We studied the effect of the PEDOT:PSS surface area on anodic capacitive peak current
Cyclic voltammetry (CV) was performed in 0.1 M potassium ferrocyanide K4[Fe(CN)6] solution to assess the capacitive peak current of PEDOT:PSS on μPtEs 10 mm and 5 mm long for six consecutive days against a control
Summary
The ability to evaluate food quality and freshness, as well as water quality, requires sensors that can operate in aqueous media. PEDOT:PSS is highly hydrophilic and unstable in liquid media because of the presence of the water-soluble PSS chain [8], which has a tendency to degenerate in an aqueous medium; with time, it can be peeled off from the electrode surface, leading to a decrease in biosensor performance [9] and limiting PEDOT:PSS application as the transducer layer in biosensors. To fabricate PEDOT:PSS transducers that are stable with long lifetime in liquid media, good adhesion is required between the transducer and the electrode surface. In this preliminary work, we studied the effect of the PEDOT:PSS surface area on anodic capacitive peak current. Field-emission scanning-electron microscopy (FESEM) was used to verify PEDOT:PSS adhesion to the platinum electrode surface after electrode measurement in aqueous media
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