The development of wearable chemical sensors is receiving a great deal of attention in view of non-invasive and continuous monitoring of physiological parameters in healthcare applications. This paper describes the development of a fully textile, wearable chemical sensor based on an organic electrochemical transistor (OECT) entirely made of conductive polymer (PEDOT:PSS). The active polymer patterns are deposited into the fabric by screen printing processes, thus allowing the device to actually “disappear” into it. We demonstrate the reliability of the proposed textile OECTs as a platform for developing chemical sensors capable to detect in real-time various redox active molecules (adrenaline, dopamine and ascorbic acid), by assessing their performance in two different experimental contexts: i) ideal operation conditions (i.e. totally dipped in an electrolyte solution); ii) real-life operation conditions (i.e. by sequentially adding few drops of electrolyte solution onto only one side of the textile sensor). The OECTs response has also been measured in artificial sweat, assessing how these sensors can be reliably used for the detection of biomarkers in body fluids. Finally, the very low operating potentials (<1 V) and absorbed power (~10−4 W) make the here described textile OECTs very appealing for portable and wearable applications.

An all PEDOT:PSS Organic Electrochemical Transistor (OECT) has been developed and used for the selective detection of dopamine (DA) in the presence of interfering compounds (ascorbic acid, AA and uric acid, UA). The selective response has been implemented using a potentiodynamic approach, by varying the operating gate voltage and the scan rate. The trans-conductance curves allow to obtain a linear calibration plot for AA, UA and DA and to separate the redox waves associated to each compound; for this purpose, the scan rate is an important parameter to achieve a good resolution. The sensitivities and limits of detection obtained with the OECT have been compared with those obtained by potential step amperometric techniques (cyclic voltammetry and differential pulse voltammetry), employing a PEDOT:PSS working electrode: our results prove that the all-PEDOT:PSS OECT sensitivities and limits of detection are comparable or even better than those obtained by DPV, a technique that employs a sophisticate potential wave and read-out system in order to maximize the performance of electrochemical sensors and that can hardly be considered a viable readout method in practical applications.

PSS films with different oxidation states, finding that the effect of the substrate on the cell growth rate is strongly cell-dependent: T98G growth is enhanced by the reduced samples, while hDF growth is more effective only on the oxidized substrates that show a strong chemical interaction with the cell culture medium.

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

An amperometric sensor based on an ITO electrode coated with ferrocene clicked PEDOT:PSS is described and the electrocatalytical performance of the device towards dopamine is assessed.