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Open Position on Wearable Electronics

Nov 302020

We are opening a position on the “Realization of Flexible Electronic Devices for Wearable Application”

The activities will be carried out within the Project PON “TEX-STYLE – Nuovi tessuti intelligenti e sostenibili multi-settoriali per design creativo e stile made-in-Italy (Novel smart, sustainable, multi-sector textiles, for creative design and made-in-Italy style)” and will include the realization and characterization of smart monitoring devices on ultra-conformable substrates (as plastic, textiles, etc).

The deadline for applications submission is December 15th 2020

For more details on the call, visit:https://dirpersonale.unica.it/concorsi/?page=assegni&bando=1072

NEW PUBLICATION: “A flexible organic memory device with a clearly disclosed resistive switching mechanism”

Nov 152018

A flexible organic memory device with a clearly disclosed resistive switching mechanism

Giulia Casula, Yan Busby, Alexis Franquet, Valentina Spampinato, Laurent Houssiau, Annalisa Bonfiglio, Piero Cosseddu

Organic Electronics, Volume 64, January 2019, Pages 209-215

Flexible electronics is one of the main challenges for future hi-tech electronics. Since information storage elements are essential in any electronic system, the development of high-performance and flexible organic memories is a key requirement. Organic resistive switching memories represent a viable and promising technology ensuring scalability, flexibility, low cost and easy processing. However, despite of the remarkable progress, organic memory reliability, long term stability, ambient operation and large-area processing still need to be improved. Moreover, the rational device implementation lacks of a clear understanding of resistive switching mechanisms. In this work, high-performance cross-bar resistive memories based on a Parylene-C resistive layer sandwiched between silver electrodes are fabricated by means of large-area and high-throughput procedure. Parylene-C is a biocompatible, thermoplastic polymer, which can be deposited at room temperature. Memory elements show a reliable and reproducible switching behavior with low operating voltages, high I_ON/I_OFF current ratio and record retention time in ambient conditions as well as high mechanical stability under bending conditions. The 3D molecular distribution of pristine and programmed devices is determined by state-of-the-art time-of-flight secondary ion mass spectrometer combined with an in-situ scanning probe microscopy (TOF-SIMS/SPM). The depth profile analysis indicates that resistive switching is driven by the formation of few localized nanometer scale conductive filaments formed by the diffusion of silver and oxygen across the organic layer which are activated, locally interrupted and re-activated during the memory cycling. The SPM images allow separating surface morphology related effects from the 3D molecular analysis and to identify some typical artefacts in TOF-SIMS image reconstructions due to preferential sputtering.

NEW PUBLICATION: “Survey on Textile Electrode Technologies for Electrocardiographic (ECG) Monitoring, from Metal Wires to Polymers”

Ott 152018

Survey on Textile Electrode Technologies for Electrocardiographic (ECG) Monitoring, from Metal Wires to Polymers

Danilo Pani, Andrea Achilli, Annalisa Bonfiglio

Advanced Materials Technologies, 1800008, (2018)

Wearable technologies represent the new frontier of vital sign monitoring in different applications, from fitness to health. With the progressive miniaturization of the electronic components, enabling the implementation of portable and hand‐held acquisition and recording devices, the research focus has shifted toward the development of effective and unobtrusive textile electrodes. These electrodes can represent an alternative to the Ag/AgCl disposable gelled electrodes usually adopted in clinical practice. This survey presents the main requirements for these electrodes, with a particular emphasis on those conceived for electrocardiographic signals, and the main challenges to be faced. An overview of the main materials and fabrication technologies presented so far in the scientific literature for this purpose is also given. The pieces of evidence resulting from the test of these electrodes clearly reveal the virtues and vices of current technologies, prospectively opening to their use in smart garments for real application scenarios.

NEW PUBLICATION: “A plastic electronic circuit based on low voltage, organic thin-film transistors for monitoring the X-Ray checking history of luggage in airports”

Ott 152018

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.

NEW PUBLICATION: “Electronic Detection of DNA Hybridization by Coupling Organic Field-Effect Transistor-Based Sensors and Hairpin-Shaped Probes”

Ott 152018

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.

NEW PUBLICATION: “Floating Gate, Organic Field-Effect Transistor-Based Sensors towards Biomedical Applications Fabricated with Large-Area Processes over Flexible Substrates”

Ott 152018

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.

OrBItaly 2017: Conference on Organic BioElectronics in Italy

Apr 112017

The 3^rd 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.

NEW PUBLICATION: “Direct imaging of defect formation in strained organic flexible electronics by Scanning Kelvin Probe Microscopy”

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.

NEW PUBLICATION: “An Inkjet-Printed, Ultralow Voltage, Flexible Organic Field Effect Transistor”

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.

NEW PUBLICATION: “Tailoring the sensing performances of an OFET-based biosensor”

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.

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