A plastic electronic circuit based on low voltage, organic thin-film transistors for monitoring the X-Ray checking history of luggage in airports
Stefano Lai, Giulia Casula, Piero Cosseddu, Laura Basiricò, Andrea Ciavatti, Franck D’Annunzio, Christophe Loussert, Vincent Fischer, Beatrice Fraboni, Massimo Barbaro, Annalisa Bonfiglio
Organic Electronics 58, 263-269 (2018)
A circuit based on low voltage Organic Field-Effect Transistors (OFETs) and conceived for monitoring the security check history of luggage in airport environment is reported. An OFET-based, direct X-Rays detector is used as sensing element and integrated in an organic circuit for digitization and memorization of the X-Ray exposure event. An integrated interface to a commercial RFID chip and antenna is also realized to allow remote readout of the circuit status. The operation mechanism of the circuit is described and a complete explanation of the strategy adopted for circuit design is reported. Simulations of the systems in Cadence® Virtuoso environment are presented: X-Ray response of the sensor is modelled, and the overall functionality of the detection and memorization schema are demonstrated. Fabrication and characterization of the circuit under X-Rays in laboratory environment are described. In particular, the correct functionality of the circuit is demonstrated, as well as its actual capability in driving the commercial RFID tag system. The robustness of the circuit to aging and exposure to X-Rays in operation conditions is finally discussed.
Electronic Detection of DNA Hybridization by Coupling Organic Field-Effect Transistor-Based Sensors and Hairpin-Shaped Probes
Corrado Napoli, Stefano Lai, Ambra Giannetti, Sara Tombelli, Francesco Baldini, Massimo Barbaro, Annalisa Bonfiglio
Sensors 18 (4), 990 (2018)
In this paper, the electronic transduction of DNA hybridization is presented by coupling organic charge-modulated field-effect transistors (OCMFETs) and hairpin-shaped probes. These probes have shown interesting properties in terms of sensitivity and selectivity in other kinds of assays, in the form of molecular beacons (MBs). Their integration with organic-transistor based sensors, never explored before, paves the way to a new class of low-cost, easy-to-use, and portable genetic sensors with enhanced performances. Thanks to the peculiar characteristics of the employed sensor, measurements can be performed at relatively high ionic strengths, thus optimizing the probes’ functionality without affecting the detection ability of the device. A complete electrical characterization of the sensor is reported, including calibration with different target concentrations in the measurement environment and selectivity evaluation. In particular, DNA hybridization detection for target concentration as low as 100 pM is demonstrated.
Floating Gate, Organic Field-Effect Transistor-Based Sensors towards Biomedical Applications Fabricated with Large-Area Processes over Flexible Substrates
Stefano Lai, Fabrizio Antonio Viola, Piero Cosseddu, Annalisa Bonfiglio
Sensors 18 (3), 688 (2018)
Organic Field-Effect Transistors (OFETs) are attracting a rising interest for the development of novel kinds of sensing platforms. In this paper, we report about a peculiar sensor device structure, namely Organic Charge-Modulated Field-Effect Transistor (OCMFET), capable of operating at low voltages and entirely fabricated with large-area techniques, ie, inkjet printing and chemical vapor deposition, that can be easily upscaled to an industrial size. Device fabrication is described, and statistical characterization of the basic electronic parameters is reported. As an effective benchmark for the application of large-area fabricated OCMFET to the biomedical field, its combination with pyroelectric materials and compressible capacitors is discussed, in order to employ the proposed device as a temperature pressure sensor. The obtained sensors are capable to operate in conditions which are relevant in the biomedical field (temperature in the range of 18.5–50 C, pressure in the range of 10 2–10 3 Pa) with reproducible and valuable performances, opening the way for the fabrication of low-cost, flexible sensing platforms.
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.
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.
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.
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.
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.
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)
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.