An all-PEDOT:PSS electrochemical transistor as a platform for biosensing

Organic electrochemical transistors (OECTs) are devices which find growing interest in the field of biological and chemical sensing. Although the OECT transduction is based on electrochemical reactions, the transistor architecture offers several advantages respect to amperometric sensors such as signal amplification, use of an easy and cheap readout electronics, low supply voltage (usually < 1 V), low power operation (< 100 μW), bio-compatibility. Moreover, they can be easily miniaturized and adapted to non-flat, flexible and even textile devices [1]. This contribution reports on the potentiality of such devices by describing an OECT based only on PEDOT:PSS as conductive material, which can be exploited to obtain low cost sensors [2, 3] with very high performance. The sensor was optimized by studying its response to different redox compounds of biological interest such as ascorbic acid, dopamine, adrenaline and uric acid. The bio-molecules react with PEDOT:PSS by extracting charge carriers from the transistor channel, and, consequently, when the analyte concentration increases the absolute value of the drain current decreases. Typically, the main drawback of such devices is the lack of selectivity which hinders their wide use in real applications. To overcome this problem we have developed a potentiodynamic approach that exploits the variation of the operating gate bias voltage in order to obtain a trans-conductance curve wherein the waves due to different redox compounds are separated. The intensity of the signal linearly depends on the analyte concentration. The sensitivities and limit of detection obtained with the OECT have been compared with those obtained by potential step amperometric techniques employing a PEDOT:PSS working electrode. The OECT performance is comparable or even better than those obtained by DPV. References: [1] I. Gualandi, M. Marzocchi, A. Achilli, D. Cavedale, A. Bonfiglio, B. Fraboni, Scientific Reports 6 (2016) 33637. [2] I. Gualandi, M. Marzocchi, E. Scavetta, M. Calienni, A. Bonfiglio, B. Fraboni, J. Mater. Chem. B 3 (2015) 6753-6762. [3] I. Gualandi, D. Tonelli, F. Mariani, E. Scavetta, M. Marzocchi, B. Fraboni, Scientific Reports 6 (2016) 35419