A simple all-PEDOT:PSS electrochemical transistor for ascorbic acid sensing

Abstract

An ascorbic acid (AA) sensor was developed by employing an organic electrochemical transistor (OECT) based only on PEDOT:PSS as conductive material. The device was prepared by spin coating using the CLEVIOS TM PH 1000 suspension (PEDOT:PSS) masking the gate and the channel areas with tape. The device was electrically characterized while the doping level of the PEDOT:PSS in the channel was controlled using both the gate electrode and the potentiostat. It was demonstrated that the current that flows in channel (Id) is controlled by the concentration of oxidized sites in the examined potential range. AA reacts with the conductive polymer leading to the extraction of charge carriers from the channel, and thus resulting in a decrease of the absolute value of Id. It was observed that Id linearly depends on the logarithm of AA concentration between 10 -6 and 10 -3 M. The OECT response to AA was studied by varying the gate voltage or the PEDOT:PSS thickness. The performance of the device for optimized conditions shows a limit of detection equal to 10 -8 M and a sensitivity of 4.5 ± 0.1 10 -6 A decade -1 . Symbol AA = Ascorbic Acid SCE = saturated calomel electrode I d = drain current that flows in the channel between source and drain collector I g = gate current that flows is measured between source and gate collector V g = potential applied to the gate electrode V d = potential applied to the drain collector E s = electrochemical potential of the source measured/applied vs SCE E g = electrochemical potential of the gate measured/applied vs SCE E d = electrochemical potential of the drain measured/applied vs SCE Among the materials employed as electrode modifiers, conducting polymers are widely used 19 . Electrochemical sensors offer many advantages with respect to the other

Hybridization of Layered Iron Hydroxide Nanoclays and Conducting Polymer for Controlled Oxygen Scavenger

“…In general, the oxidation process of Fe 2+ (−0.506 V vs. saturated calomel electrode (SCE)) is thermodynamically favored combined with the reduction of oxygen (0.57 V vs. SCE) so that the green rust could be easily transformed to goethite (Fe(III)OOH) under ambient air as we reported in the previous literature [22]. However, the oxidation potential of PEDOT:PSS is relatively higher than that of Fe 2+ [29,30], and thus the oxidation of PEDOT by O 2 is less feasible than oxidation of Fe 2+ . The action of PEDOT on the GR surface could be (i) protecting GR from oxidation, and (ii) retarding oxidation by atmospheric O 2 through adjusted reduction potential.…”

Rising advancements in the application of PEDOT:PSS as a prosperous transparent and flexible electrode material for solution-processed organic electronics

“…PEDOT:PSS has also been suggested as a promising material for the fabrication of G, S, and D polymer electrodes for solution-processed flexible organic transistors like OFETs and OECTs [16,116]. For these devices, the solution processability of PEDOT:PSS is also frequently incorporated with the outstanding electrical and optical properties of Ag NWs, CNTs, and graphene to realize high-performance composite electrodes for OTFTs [64].…”

Fabrication and Use of Organic Electrochemical Transistors for Sensing of Metabolites in Aqueous Media

“…It should be pointed out that there are also some examples of enzyme-free OECTs where the electroactive target molecules, such as ascorbic acid [57] (Figure 2) or dopamine [58], are directly electrooxidized on the gate electrode. However, this is often at the price of weak selectivity compared to the extreme selectivity of most enzymes.…”

“…Illustration of ascorbic acid oxidation at the gate electrode; PEDOT:PSS is, in turn, reduced leading to a drain current decrease. Reproduced from [57] with permission of The Royal Society of Chemistry.…”

“…Gualandi et al developed an all-PEDOT:PSS OECT sensor for ascorbic acid detection [57], without the presence of either enzyme or other redox mediators; ascorbic acid was directly electrooxidized at the gate electrode. A limit of detection of 13 nM and a sensitivity of 4.5 × 10 −6 A decade −1 have been reached, with a linearity domain between 10 −6 and 10 −3 M.…”