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Apr 112017
 

The 3rd Conference on Organic BioElectronics in Italy – 2017 (OrBItaly – 2017) will be held on October 25 – 27, 2017 in Cagliari, Italy.

ORBITALY – ORganic BIoelectronics ITALY is a cross-disciplinary, international, conference that has attracted in the years a growing interest by scientists coming from all over the world on the emerging field of Organic Bioelectronics (see the list of the past speakers at: http://www.orbitaly.com/speakers.html).

OrBItaly-2017 will bring together the most excellent researchers in the field to discuss fundamental aspects of organic bioelectronics and to exchange ideas on future materials, technologies, and applications.

Please visit the OrBItaly-2017 web-site  http://sites.unica.it/orbitaly2017/  for further details.

 Scritto da in 11 aprile 2017  Avvisi  Commenti disabilitati su OrBItaly 2017: Conference on Organic BioElectronics in Italy
Dic 222016
 

Direct imaging of defect formation in strained organic flexible electronics by Scanning Kelvin Probe Microscopy

Tobias Cramer, Lorenzo Travaglini, Stefano Lai, Luca Patruno, Stefano de Miranda, Annalisa Bonfiglio, Piero Cosseddu, Beatrice Fraboni

Scientific Reports 6, 38203 (2016)

The development of new materials and devices for flexible electronics depends crucially on the understanding of how strain affects electronic material properties at the nano-scale. Scanning Kelvin-Probe Microscopy (SKPM) is a unique technique for nanoelectronic investigations as it combines non-invasive measurement of surface topography and surface electrical potential. Here we show that SKPM in non-contact mode is feasible on deformed flexible samples and allows to identify strain induced electronic defects. As an example we apply the technique to investigate the strain response of organic thin film transistors containing TIPS-pentacene patterned on polymer foils. Controlled surface strain is induced in the semiconducting layer by bending the transistor substrate. The amount of local strain is quantified by a mathematical model describing the bending mechanics. We find that the step-wise reduction of device performance at critical bending radii is caused by the formation of nano-cracks in the microcrystal morphology of the TIPS-pentacene film. The cracks are easily identified due to the abrupt variation in SKPM surface potential caused by a local increase in resistance. Importantly, the strong surface adhesion of microcrystals to the elastic dielectric allows to maintain a conductive path also after fracture thus providing the opportunity to attenuate strain effects.

 Scritto da in 22 dicembre 2016  Avvisi  Commenti disabilitati su NEW PUBLICATION: “Direct imaging of defect formation in strained organic flexible electronics by Scanning Kelvin Probe Microscopy”
Dic 222016
 

An Inkjet-Printed, Ultralow Voltage, Flexible Organic Field Effect Transistor

Silvia Conti, Stefano Lai, Piero Cosseddu, Annalisa Bonfiglio

Adv. Mater. Technol. 2016, 1600212

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.

 Scritto da in 22 dicembre 2016  Avvisi  Commenti disabilitati su NEW PUBLICATION: “An Inkjet-Printed, Ultralow Voltage, Flexible Organic Field Effect Transistor”
Apr 282016
 

Tailoring the sensing performances of an OFET-based biosensor

Stefano Lai, Massimo Barbaro, Annalisa Bonfiglio

Sensors and Actuators B: Chemical, Volume 233, pp. 314-319 (2016)

An approach for the fabrication of organic-FET based biosensors with precisely tailored sensing performances is here proposed. A specific device structure, namely Organic Charge-Modulated Field-Effect Transistor (OCMFET), has been analyzed in details and modeled in order to move beyond the pure phenomenological observation of its biochemical sensitivity and precisely determining its sensitivity. Thanks to a complete comprehension of the relationship between sensing ability and device structure, design rules have been derived for tailoring the sensing performances. The layout of the sensor has been optimized according to these design rules. The effectiveness of the approach and of the design is demonstrated by providing a complete electrical characterization of the device in a specific application, namely DNA hybridization detection. Record performances of the OCMFET for direct DNA hybridization detection, both in terms of sensitivity and selectivity, will be reported. As the sensing ability of the device is completely independent of the semiconductor employed for the transistor, the presented results are completely general and may be replicated also for other kinds of semiconductors, thus paving the way to a new generation of biosensing devices based on a variety of semiconducting materials.

 Scritto da in 28 aprile 2016  Avvisi  Commenti disabilitati su NEW PUBLICATION: “Tailoring the sensing performances of an OFET-based biosensor”
Dic 152015
 

Toward Low-Voltage and Bendable X-Ray Direct Detectors Based on Organic Semiconducting Single Crystals

A. Ciavatti, E. Capria, A. Fraleoni-Morgera, G. Tromba,  D. Dreossi, P. J. Sellin, P. Cosseddu, A. Bonfiglio, and B. Fraboni

Adv. Mater. 27 (44), pg. 7213–7220, 2015

Organic materials have been mainly proposed as ionizing radiation detectors in the indirect conversion approach. The first thin and bendable X-ray direct detectors are realized (directly converting X-photons into an electric signal) based on organic semiconducting single crystals that possess enhanced sensitivity, low operating voltage (≈5 V), and a minimum detectable dose rate of 50 μGy s−1.

 Scritto da in 15 dicembre 2015  Avvisi  Commenti disabilitati su NEW PUBLICATION:”Toward Low-Voltage and Bendable X-Ray Direct Detectors Based on Organic Semiconducting Single Crystals”
Dic 152015
 

Integration of an Organic Resistive Memory with a Pressure-Sensitive Element on a Fully Flexible Substrate

Giulia Casula, Piero Cosseddu, Annalisa Bonfiglio

Adv. Electron. Mater. 1, 12 (2015)

aelm201570048-gra-0001-m

Organic memories are promising candidates for the fabrication of electronic integrated systems, including sensing units, and for their use in applications such as smart packaging and artificial skin. Flexible arrays of mechanically switchable, organic resistive memory elements are successfully developed by Giulia Casula and co-workers in article number 1500234. The pressure-triggered memory system is obtained by connecting a memory element in series with a pressure-sensitive rubber. It can be operated in ambient conditions with high retention time.

 Scritto da in 15 dicembre 2015  Avvisi  Commenti disabilitati su NEW PUBLICATION: “Integration of an Organic Resistive Memory with a Pressure-Sensitive Element on a Fully Flexible Substrate”
Set 092015
 

The role of polarization-induced reorientation of DNA strands on organic field-effect transistor-based biosensors sensitivity at high ionic strength

Stefano Lai, Massimo Barbaro, Annalisa Bonfiglio

Appl. Phys. Lett. 107, 103301 (2015)

The detection of the intrinsic charge of biochemical molecules is a promising strategy for the fabrication of field-effect transistor (FET)-based sensors for direct, non-destructive detection of several biochemical reactions. Nevertheless, the high ionic concentration of standard environments for biochemical species represents a significant limitation to this sensing strategy. Here, an investigation on the physical mechanisms behind the ability of an organic FET-based sensor to detect DNA hybridization at high ionic strengths is proposed. The capability of the device to correctly detect single-stranded DNA oligonucleotides and their hybridization with a complementary target sequence has been analyzed in detail. In particular, the electrical response in solutions with different ionic strengths was investigated and put in relation with the nano-scale properties of DNA strands employed as receptors. Fluorescence analysis shows that it is possible to electrically modify their orientation and consequently improve the device sensitivity in conditions close to those occurring during hybridization.

 Scritto da in 9 settembre 2015  Avvisi  Commenti disabilitati su NEW PUBLICATION:”The role of polarization-induced reorientation of DNA strands on organic field-effect transistor-based biosensors sensitivity at high ionic strength”
Set 022015
 

Self-encapsulation of organic thin film transistors by means of ion implantation

P. Cosseddu, B. Fraboni, A. Scidà, Y.Q. Wang, M. Nastasi, A. Bonfiglio

Synthetic Metals, Volume 209, November 2015, Pages 178-182

doi:10.1016/j.synthmet.2015.07.018

Long-term stability of devices based on organic materials is still impeding the diffusion of these structures in real applications. In this paper we have investigated the effects of low energy, combined, ion implantation (N and Ne) in the evolution of the electrical performances of pentacene-based Organic Thin Film Transistors (OTFTs) over time by means of current–voltage and photocurrent spectroscopy analyses. We have demonstrated that the selected combination of ions allows reducing the degradation of charge carriers mobility, and also stabilization of the devices threshold voltage over a long time (over 2000 h).

 Scritto da in 2 settembre 2015  Avvisi  Commenti disabilitati su NEW PUBLICATION: “Self-encapsulation of organic thin film transistors by means of ion implantation”
Mag 262015
 

Maria Girleanu , Giulia Casula , Christian Blanck , Marc Schmutz , Christophe Contal , Navaphun Kayunkid , Piero Cosseddu , Annalisa Bonfiglio , Ovidiu Ersen , and Martin Brinkmann

J. Phys. Chem. C, 2015, 119 (23), pp 13115–13123
DOI: 10.1021/acs.jpcc.5b03646
Publication Date (Web): May 22, 2015
Nucleation and growth of silver nanoparticles were studied on the surface of an n-type organic semi-conductor (N′-bis(n-octyl)-dicyanoperylene-3,4:9,10- bis(dicarboxyimide) (N1400)) as a function of the deposition rate τ and the substrate temperature Ts. Electron tomography was used to probe the bulk diffusion of Ag in the N1400 layers. No Ag nanoparticles are formed in the bulk of N1400 even for high substrate temperatures Ts = 125 °C, indicating that Ag diffusion in the organic semiconductor is marginal. The NPs distribution on the surface of N1400 is essentially determined by the surface roughness of the N1400 films. A transition in the nucleation mode of Ag NPs on N1400 is evidenced as a function of Ts: for Ts ≤ 50°C, Ag NPs form random patterns whereas for Ts ≥ 75 °C linear arrays of aligned NPs are observed. Such arrays result from step edge decoration of the N1400 terraces. The surface density of Ag NPs is thermally activated but the activation energy depends on the structure of the N1400 films: the smaller the crystal size of the N1400 grains, the larger the activation energy.
 Scritto da in 26 maggio 2015  Avvisi  Commenti disabilitati su NEW PUBLICATION: “Controlling the Growth of Silver Nanoparticles on Thin Films of an n-type Molecular Semiconductor”
Mar 062015
 

An organic transistor-based system for reference-less electrophysiological monitoring of excitable cells

Andrea Spanu, Stefano Lai, Piero Cosseddu, M. Tedesco, Sergio Martinoia & Annalisa Bonfiglio

Scientific Reports 5, Article number: 8807, doi:10.1038/srep08807

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.

 Scritto da in 6 marzo 2015  Avvisi  Commenti disabilitati su NEW PUBLICATION: “An organic transistor-based system for reference-less electrophysiological monitoring of excitable cells”
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