An organic ultralow voltage field effect transistor for DNA hybridization detection is presented. The transduction mechanism is based on a field-effect modulation due to the electrical charge of the oligonucleotides, so label-free detection can be performed. The device shows a sub-nanometer detection limit and unprecedented selectivity with respect to single nucleotide polymorphism.

The attention on the application of organic electronics for the detection of ionizing radiation is rapidly growing among the international scientific community, due to the great potential of the organic technology to enable large-area conformable sensor panels. However, high-energy photon absorption is challenging as organic materials are constituted of atoms with low atomic numbers.Here it is reported how, by synthesizing new solution-processable organic molecules derived from 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene) and 2,8-Difluoro-5,11bis(triethylsilylethynyl)anthradithiophene (diF-TES-ADT), with Ge-substitution in place of the Si atoms to increase the material atomic number, it is possible to boost the X-ray detection performance of organic thin films on flexible plastic substrates. TIPGe-pentacene based flexibleOTFTs show high electrical performance with higher mobility (0.4 cm 2 V -1 s -1 ) and enhanced X-ray sensitivity, up to 9.0 x 10 5 µC Gy -1 cm -3 , with respect to TIPS-pentacene based detectors. Moreover, similar results are obtained for diF-TEG-ADT devices, confirming that the proposed strategy, i.e.increasing the atomic number of organic molecules by chemical tailoring to improve X-ray sensitivity, can be generalized to organic thin film detectors, combining high X-ray absorption, mechanical flexibility and large area processing.

In the last four decades, substantial advances have been done in the understanding of the electrical behavior of excitable cells. From the introduction in the early 70's of the Ion Sensitive Field Effect Transistor (ISFET), a lot of effort has been put in the development of more and more performing transistor-based devices to reliably interface electrogenic cells such as, for example, cardiac myocytes and neurons. However, depending on the type of application, the electronic devices used to this aim face several problems like the intrinsic rigidity of the materials (associated with foreign body rejection reactions), lack of transparency and the presence of a reference electrode. Here, an innovative system based on a novel kind of organic thin film transistor (OTFT), called organic charge modulated FET (OCMFET), is proposed as a flexible, transparent, reference-less transducer of the electrical activity of electrogenic cells. The exploitation of organic electronics in interfacing the living matters will open up new perspectives in the electrophysiological field allowing us to head toward a modern era of flexible, reference-less, and low cost probes with high-spatial and high-temporal resolution for a new generation of in-vitro and in-vivo monitoring platforms.

A very simple procedure for fabricating inkjet‐printed organic field effect transistors (OFETs) is reported. A reliable process for the deposition of a thin and uniform polymeric dielectric film of poly(4‐vinylphenol) (PVP) is established as a key factor for obtaining high performance devices operating at low voltages. To this aim, ink formulations, printing parameters, and cross‐linking processes are investigated. Morphological characterization of the fabricated films by means of contact profilometry and atomic force micro­scopy is provided, as well as capacitive measurements proving ideal dielectric properties. OFET structures based on PVP gate dielectric are reported: in particular, inkjet‐printed devices operated at voltages below 1 V with remarkable transistor performances such as high charge carrier mobility and low subthreshold swing are presented.

We investigate and optimize the Aerosol Jet Printing of PEDOT:PSS by studying the role of parameters determining the final quality of the printed features. Printing thin films of organic materials requires a high control in the deposition process to control the morphology/structure of the films that determine the electrical and functional performance of organic devices. We studied aerosol jet printed lines of the PEDOT:PSS semiconductive polymer on flexible Kapton substrates. We choose the focus ratio, defined as the ratio between the sheath and carrier gas flow rates, as the main parameter that best characterizes the process and hence the characteristics of printed lines. A detailed analysis of the line width and thickness, as a function of the focus ratio and carrier gas flow for different nozzle sizes and sheath gas flow rates, is reported. The edge profile definition of printed PEDOT:PSS lines has been found to be affected by a combination of overspray, typical of aerosol deposition, and pinholes due to the Kapton/PEDOT:PSS interaction, while their core profile results to be almost defects free. An optimal printing window for different nozzle sizes has been determined in terms of a minimization of overspray/pinholes effects with respect to the whole line width. Finally, an array of whole-plastic, planar Organic Electrochemical Transistors, having both the channel and the gate electrode made of PEDOT:PSS, has been manufactured using the best combination of process parameters. Transistors have been characterized for different channel/gate area ratios and the transconductance analysed as a function of channel to gate area.

A novel organic transistor‐based sensor for direct X‐ray detection is proposed. The device operates at low voltages (≤3 V) and is entirely fabricated on flexible, plastic substrates with techniques that can be easily upscaled to an industrial scale. It is claimed that flexible, low voltage organic transistors have never been employed as direct ionizing radiation detectors, as two terminal photodetectors are typically considered for this application. It is demonstrated that, differently from two‐terminal photodetectors, X‐ray detection ability of the proposed sensor can be tuned acting on the transistor polarization conditions. Thanks to such a peculiar feature of the device, outstanding values of sensitivity are observed (up to 1200 nC Gy−1), much larger than the ones reported for two terminal direct organic photodetectors. It is notable that, the reported performances have been obtained using as sensing layer a standard, commercially available organic semiconductor: a complete explanation of the mechanism behind the detection ability is thoroughly discussed. The device functionality is perfectly maintained even after the exposure to high X‐ray doses (160 Gy), thus demonstrating the significant radiation hardness of the detector.

Organic thin film transistors have been fabricated on plastic substrates using a combination of two\ud ultrathin insulating films, namely a 6 nm Al2O3 film (grown by UV-Ozone treatment of a\ud pre-deposited aluminium film) and a 25 nm parylene C film deposited by vapour phase, as gate\ud dielectric. They show a very low leakage current density, around 2109 A/cm2, and, most\ud importantly, can be operated at voltages below 1V. We demonstrate that this low-cost technique is\ud highly reproducible and represents a step forward for the routine fabrication of ultra-low voltage\ud plastic electronics

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