Chemo and biodetection in liquid with organic transistor

In the past, quality and quantity of the substances could be evaluated only in analytical chemistry laboratories, well-equipped with centralized and powerful data centres. The rising of miniaturized technology has made possible to conceive the realization of portable devices, i.e. chemical sensors capable to analyse small quantities in situ. Nowadays, the availability of portable devices allows to test those samples which are dicult or impossible to transport for long distances without degradation. This work concerns the realization of two kinds of devices for detection of chemical and biological species in liquids by using organic transistor technology. One device, which is named Organic Charge Modulated Field Eect Transistor (OCMFET), is a charge sensor which was tested as pH and DNA sensor. The other device is an Organic Electrochemical Transistor (OECT) entirely made of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) which was realized by ink-jet printing. As these devices can be fabricated with low-cost processes, they can be considered portable and disposable. A brief introduction on sensors, organic technology and the aim of this work is de- scribed in chapter one. In order to explain the reasons and the specic choices behind the development of these sensors, an overview of the most relevant sensing applications realized with Organic Thin Film Transistors and Organic Electrochemical Transistors is reported in chapter two. The working principle, the materials and methods and the recorded experimental results related to the OCMFET are treated in chapter three. A brief introduction on OECTs with a PEDOT:PSS channel and the study carried out to elucidate the operating regime of the OECT all made of PEDOT:PSS is treated in chapter four. The conclusions about this work are brie y summarized in chapter ve. An overview on organic semiconductors and Organic Thin Film Transistors (OTFTs), the electrochemical techniques used in this work are treated in the appendixes.