is coupled with the gate electrode via an electrolyte. The application of a bias to a polarizable gate electrode may either induce the formation of two electrical double layers or allow the intercalations of ions in the OSC film. In the first case, the transistors are operating in the field-effect mode and they are called electrolyte-gated organic field-effect transistors (EGOFETs), while in the second case, an electrochemical doping occurs and the devices are named organic electrochemical transistors (OECTs). EGOTs can operate with voltages below 1 V and are extremely sensitive to any change that occurs either on the gate electrode or on the OSC. For this reason, these devices are exploited in biosensing applications for the detection of specific binding events occurring at the gate surface, which is functionalized to match the targeted analyte. Indeed, EGOTs can be used as biosensors to detect low concentrations of relevant biomolecules (proteins, [1][2][3] nucleic acids, [4,5] drugs [6][7][8] ), but the manufacturing of these devices for scale production and commercial applications is still far to be achieved. In fact, one of the main disadvantages of EGOTs is their poor operational stability, whose origins are still under investigation. [9][10][11] Several works in the literature concerning organic transistors address the instability related to the electrical bias stress (EBS), but most of the proposed models deal with solid-state organic field-effect transistor (OFET). [12,13] For this kind of devices, the EBS is responsible for mobile charges trapping either in the OSC material, or in the insulating dielectric, or at the OSC/dielectric interface. This mechanism is usually related to high-voltageinduced water electrolysis phenomena affecting adsorbed adventitious water molecules present on the oxide surface. [12,14] The EBS in EGOTs should be ascribed to different causes since the low operating voltages prevent any water electrolysis to occur. In addition to this, the different nature of the dielectric material avoids any charge accumulation in the dielectric, being the ions in the electrolyte free to move. Concerning the operational stability of EGOTs, only a limited number of works are found in the literature addressing the issue. For instance, Blasi et al. investigated the long-term stability of EGOFETs based on poly(3hexylthiophene) (P3HT), showing that the maximum current drift over time could be modeled with a biexponential function, in which two processes with different timescales occur. [15] Electrolyte-gated organic transistors (EGOTs) are emerging as an important tool in advanced biosensing applications. However, their widespread exploitation is still limited by their poor operational stability. In order to understand the causes of this unreliability, the proposed study focuses on the influence of electrical bias stress (EBS) on EGOTs operating in aqueous electrolytes. Poly(3-hexylthiophene) (P3HT)-and poly[3-(5-carboxypentyl)thiophene)] (P3CPT)-based transistors are studied under the application o...

In biosensing applications, the exploitation of organic transistors gated via a liquid electrolyte has increased in the last years thanks to their enormous advantages in terms of sensitivity, low cost and power consumption. However, a practical aspect limiting the use of these devices in real applications is the contamination of the organic material, which represents an obstacle for the realization of a portable sensing platform based on electrolyte-gated organic transistors (EGOTs). In this work, a novel contamination-free microfluidic platform allowing differential measurements is presented and validated through finite element modeling simulations. The proposed design allows the exposure of the sensing electrode without contaminating the EGOT device during the whole sensing tests protocol. Furthermore, the platform is exploited to perform the detection of bovine serum albumin (BSA) as a validation test for the introduced differential protocol, demonstrating the capability to detect BSA at 1 pM concentration. The lack of contamination and the differential measurements provided in this work can be the first steps towards the realization of a reliable EGOT-based portable sensing instrument.

A programmable dynamic cell culture chamber compatible with a standard multi-well plate was designed and characterized. The system is integrated with an array of OECT biosensors, in view of an in-situ monitoring of the dynamic cultures.

No abstract

In this work a new microfluidic platform is designed and validated to remove analyte contamination problem in EGOFETs biosensors.