The role of pre-synaptic DC bias is investigated in three-terminal organic neuromorphic architectures based on Electrolyte gated Organic Transistors - EGOTs. By means of presynaptic offset it is possible to finely control the number of discrete conductance states in short-term plasticity experiments, to obtain, at will, both depressive and facilitating response in the same neuromorphic device and to set the ratio between two subsequent pulses in paired-pulse experiments. The charge dynamics leading to these important features are discussed in relationship with macroscopic device figures of merit such as conductivity and transconductance, establishing a novel key enabling parameter in devising the operation of neuromorphic organic electronics.

Organic Electrochemical Transistors (OECTs) are suitable for developing ultra-sensitive bioelectronic sensors. In the OECT architecture, the source-drain channel is made of a conductive polymer film either cast from a formulated dispersion or electrodeposited from a monomer solution. The commercial poly(3,4-ethylenedioxidethiophene)/poly(styrene sulfonate) (PEDOT:PSS) water dispersion is the workhorse of organic bioelectronics for its high conductance, low impact and ease of processability. In this study, a hybrid OECT channel fabrication strategy is presented, where electrochemical deposition of a PEDOT/X (with X indicating the counterion) is performed on a dispersion-cast PEDOT:PSS film. Six different counterions where used: X = PSS, Nafion, Hyaluronate, Dextran sulfate, Dexamethasone phosphate and tauroursodeoxycholic acid, each potentially endowing OECT with additional functions such as ion exchange and pharmacological activity upon release of X. The PEDOT/X-PEDOT:PSS bilayers were characterized by means of electrochemical impedance spectroscopy (EIS), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and focused ion beam tomography combined with scanning electron microscopy (FIB-SEM). In addition, their respective OECTs were characterized and compared to PEDOT:PSS OECT. Our results show that the hybrid bilayer strategy is viable to fabricate multifunctional OECTs with biologically-relevant function, thereby retaining the outstanding figures of merit of commercial PEDOT:PSS.

Successful translation of organic transistors as sensors and transducers to clinical settings is hampered by safety and stability issues. The operation of such devices demands driving voltages across the biotic/abiotic interface, which may result in undesired electrochemical reactions that may harm both the patient and the device. In this study, a novel operational mode is presented for electrolyte-gated organic transistors that avoid these drawbacks: the common-drain/grounded-source configuration. This approach reverts the standard common-source/common-ground configuration and achieves maximum signal amplification while applying null net bias across the electrolyte, with no parasitic currents. The viability of the proposed configuration is demonstrated by recording in vivo the somatosensory evoked activity from the barrel cortex of rats. The main inherent advantage of transistors with respect to passive electrodes is preserved in the proposed scheme: a superior signal-to-noise ratio is achieved which enables the detection of evoked activity at the single-trial level. Then, common-drain/grounded-source organic transistors are proposed as ideal candidate devices for a harmless translational recording platform.

Multi-electrode arrays with 3D micropillars allow the recording of electrophys-iological signals in vitro with higher precision and signal-to-noise ratio than planar arrays. This is the result of the tight interaction between the 3D elec-trode and the cell membrane. Most 3D electrodes are manufactured on rigid substrates and their integration on flexible substrates is largely unexplored. Here, a straightforward approach is presented for fabricating soft inter-faces featuring 3D poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) micropillars on a soft flexible substrate made of polydimethyl-siloxane (PDMS). Large-area isotropic arrays of PEDOT:PSS micropillars with tailored geometric area, surface properties, and electrochemical characteris-tics are fabricated via a combination of soft-lithography and electrodeposi-tion. A 60% increase in capacitance is achieved for high density micropillars compared to planar electrodes and this is found to be correlated with the increased electroactive surface area. Furthermore, 3D PEDOT:PSS micro-pillars support adhesion, growth and differentiation of SH-SY5Y cells, and influence the direction of neurite outgrowth. Finally, by virtue of their elas-ticity, soft micropillars act as excellent anchoring loci for elongating neurites, facilitating their bending and twisting around the micropillar, increasing the number of contact points between the cells and the electrode, a key require-ment to obtain high performance neural interfaces.

Charge injection in Organic Field Effect Transistors is investigated by monitoring in real-time the electrical conduction, while in situ growing pentacene films. The source and drain electrodes are made of gold functionalized with alkanethiol Self-Assembled Monolayers (SAMs), whose number of carbon atoms ranges from 5 to 10. Measuring the current flowing into the channel allows us to establish a correlation between the charge injection and the pentacene film growth. In particular, the thickness dependence of both the charge mobility and the charge carrier accumulation can be explained in terms of the molecular order at the interface between the pentacene films and the SAMs. Specifically, the threshold voltage, contact resistance and temperature-dependent constant exhibit parabolic trends for increasing alkanethiol chain length. Conversely, both the band mobility and the charge mobility are characterized by oscillations that follow an odd-even trend with a linear decay for increasing number of the carbon atoms. These results corroborate the theoretical interpretation, previously proposed by Stoliar et al., that the odd-even effect is ascribable to the order degree and orientation of the pentacene molecules interacting with the SAMs, while the parabolic trend depends on the chain length of the alkanethiol SAMs.

Organic neuromorphic devices mimic signal processing features of biological synapses, with short-term plasticity, STP, modulated by the frequency of the input voltage pulses. Here, an artificial synapse, made of intracortical microelectrodes, is demonstrated that exhibits either depressive or facilitative STP. The crossover between the two STP regimes is controlled by the frequency of the input voltage. STP features are described with an equivalent circuit where an inductance component is introduced in parallel with the RC circuit associated with poly(3,4-ethylenedioxythiophene)/polystyrene sulfonate (PEDOT/PSS)||electrolyte interface. The proposed RLC circuit explains the physical origin of the observed STP and its two timescales in terms of charge build up in PEDOT/PSS.

The nanomechanical properties of ultrathin and nanostructured films of rigid electronic materials on soft substrates are of crucial relevance to realize materials and devices for stretchable electronics. Of particular interest are bending deformations in buckled nanometer-thick films or patterned networks of rigid materials as they can be exploited to compensate for the missing tensile elasticity. Here, we perform atomic force microscopy indentation experiments and electrical measurements to characterize the nanomechanics of ultrathin gold films on a polydimethylsiloxane (PDMS) elastomer. The measured force-indentation data can be analyzed in terms of a simple analytical model describing a bending plate on a semi-infinite soft substrate. The resulting method enables us to quantify the local Young's modulus of elasticity of the nanometer-thick film. Systematic variation of the gold layer thickness reveals the presence of a diffuse interface between the metal film and the elastomer substrate that does not contribute to the bending stiffness. The effect is associated with gold clusters that penetrate the silicone and are not directly connected to the ultrathin film. Only above a critical layer thickness, percolation of the metallic thin film happens, causing a linear increase in bending stiffness and electrical conductivity.

Poly(3,4-ethylenedioxythiophene)-Nafion (PEDOT:Nafion) is emerging as a promising alternative to PEDOT-polystyrene sulfonate (PEDOT:PSS) in organic bioelectronics. However, the biocompatibility of PEDOT:Nafion has not been investigated to date, limiting its deployment toward in vivo applications such as neural recording and stimulation. In the present study, the in vitro cytotoxicity of PEDOT:Nafion coatings, obtained by a water-based PEDOT:Nafion formulation, was evaluated using a primary cell culture of rat fibroblasts. The surface of PEDOT:Nafion coating was characterized by Atomic Force Microscopy (AFM) and water contact angle measurements. Fibroblasts adhesion and morphology was investigated by scanning electron microscopy (SEM) and AFM measurements. Cell proliferation was assessed by fluorescence microscopy, while cell viability was quantified by 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT), lactate dehydrogenase (LDH) and neutral red assays. The results showed that PEDOT:Nafion coatings obtained by the water dispersion were not cytotoxic, making the latter a reliable alternative to PEDOT:PSS dispersion, especially in terms of chronic in vivo applications.

Circular economy (CE) is now gaining attention in academia and industry as an emerging model for minimizing primary resource depletion, waste and greenhouse gas emissions. In the present work, we present a learning pathway, designed for high schools, useful to introduce some basic concepts of CE among youngsters by starting from a laboratory experience. The path was developed in the framework of the European project Raw Matters Ambassadors at Schools (RM@Schools), an innovative program to make science education attractive for youngsters which and to promote a wide dissemination action on raw material-related themes in Schools and Society. In this context, lab experiments to approach raw materials (RMs) considered critical by EU and the necessity of their recovery were set up for high school students. Phosphate rock (P) is one of the critical RMs for EU, and it is primarily used in agriculture. After 2033 Iit is expected a huge decline in P extraction and consequently, a dramatic decrease in fertilizers, food and feed. The goal of the lab experience presented here is to educate students that P can be recovered from secondary resources such as urine, a component of wastewater. The laboratory activities are planned in a theoretical training under the teacher guidance and another practice where students become the main protagonists of all phases of the work (from design to evaluation). The laboratory activity is composed by three experiments with various levels of difficult. By using the material created for this learning path, students become familiar with the concept of biogeochemical cycles and specifically nitrogen and phosphorous cycling, and learn that in CE end-of-life products are considered as resources for another cycle. In addition, consideration must be given to the interactions between materials to determine the best circular solution. Students can be aware of the benefits of closing material loops in a simple and engaging way.

Circular economy (CE) is now gaining attention in academia and industry as an emerging model for minimizing primary resource depletion, waste and greenhouse gas emissions. In the present work, we present a learning pathway, designed for high schools, useful to introduce some basic concepts of CE among youngsters by starting from a laboratory experience. Virtual presentation at the conference The Future of Education - 11th Edition. Recorded video conference on the Pixel Conferences youtube channel.

Circular economy (CE) is now gaining attention in academia and industry as an emerging model for minimizing primary resource depletion, waste and greenhouse gas emissions. In the present work, we present a learning pathway, designed for high schools, useful to introduce some basic concepts of CE among youngsters by starting from a laboratory experience. The path was developed in the framework of the European project Raw Matters Ambassadors at Schools (RM@Schools), an innovative program to make science education attractive for youngsters which and to promote a wide dissemination action on raw material-related themes in Schools and Society. In this context, lab experiments to approach raw materials (RMs) considered critical by EU and the necessity of their recovery were set up for high school students. Phosphate rock (P) is one of the critical RMs for EU, and it is primarily used in agriculture. After 2033 Iit is expected a huge decline in P extraction and consequently, a dramatic decrease in fertilizers, food and feed. The goal of the lab experience presented here is to educate students that P can be recovered from secondary resources such as urine, a component of wastewater. The laboratory activities are planned in a theoretical training under the teacher guidance and another practice where students become the main protagonists of all phases of the work (from design to evaluation). The laboratory activity is composed by three experiments with various levels of difficult. By using the material created for this learning path, students become familiar with the concept of biogeochemical cycles and specifically nitrogen and phosphorous cycling, and learn that in CE end-of-life products are considered as resources for another cycle. In addition, consideration must be given to the interactions between materials to determine the best circular solution. Students can be aware of the benefits of closing material loops in a simple and engaging way.

A paradigm shift towards a new industrial policy aimed at sustainability and innovation is underway in Europe. Circular Economy (CE) is a model to rethinks the systems of production and consumption to create a waste-free future. This transition requires a cultural and structural change that can be obtained by aligning the educational programs in order to train people needed to build a sustainable development in Europe. In the present work, we present a learning pathway, designed for High schools, useful to introduce some basic concepts of CE among youngsters by starting from a laboratory experience which is part of the European project Raw Matters Ambassadors at Schools, an innovative program to make science education attractive for youngsters [1]. RM@Schools promotes a wide dissemination action on RM-related themes in Schools and Society through strategic European partnerships among Research, School, and Industry. In this context, the students of a high school class of Bologna (IT) were involved in lab experiments to approach the topic of raw materials (RMs) considered critical by EU and the necessity of their recovery. Phosphate rock (P) is one of the critical RM for EU, and it is primarily used in agriculture [2-3]. It is expected after 2033 a huge decline in P extraction and consequently, a dramatic decrease in fertilizers, food and feed [4]. The goal of the lab experience was to educate students that P can be recovered from secondary resources such as urine, a component of wastewater. The laboratory activities were planned in a theoretical training under the guidance of the teacher and another practice where students become the main protagonists of all phases of the work (from design to evaluation). The laboratory activity involved three experiments with various levels of difficult: i) production of synthetic urine from which struvite is extracted; ii) to build a simple reactor to recovery struvite; iii) to test the fertilizer property of struvite on basil plants in hydroponics. By using the material created for this learning path, students become familiar with the concept of biogeochemical cycles and specifically nitrogen and phosphorous cycling and learn that in CE end-of-life products must be considered as resources for another cycle. In addition, interactions between materials must be considered in order to define the best circular solution. Awareness of the benefits of closing material loops can be raised among students in a simple and engaging way.

Reversibly tunable short-term plasticity (STP) of the channel current in organic neuromorphic devices is demonstrated with a three-terminal architecture. Electrolyte-gated organic transistors--EGOTs--are driven with square voltage pulses at the drain electrodes, while the gate bias enables the modulation of the amplitude and characteristic time scale of the depressive STP spiking response up to 1 order of magnitude. The gate potential sets the baseline and the steady-state current, preluding multilevel memory writing. The fine-tuning of the STP response, which is not possible with two-electrode organic neuromorphic devices, is reversible and does not imply chemical modifications of the active layer.

Poly(3,4-ethylentedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is one of the most studied materials for organic bioelectronics, supercapacitors and organic photovoltaics. Its low impedance is ascribed to the so-called volumetric capacitance, a property that phenomenologically correlates the capacitive coupling/charge storage in devices to the PEDOT:PSS volume/thickness. Here we investigate the correlation between the capacitance and the electroactive surface area (ESA) for large-volume spin-cast PEDOT:PSS electrodes. We measure the capacitance with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), and characterize the surface morphology by atomic force microscopy and X-ray photoelectron spectroscopy. Capacitance of PEDOT:PSS films scales with volume up to ~5 × 106 ?m3 but is saturated at larger volumes. This scaling behavior is paralleled by the scaling of the ESA, hence the ratio between the effective capacitance and ESA remains constant across the whole data set, thus showing that the specific areal capacitance is indeed the relevant material property of PEDOT:PSS. EIS data fit supports the experimental evidence obtained by CV, further revealing that the diffusion time constant is also saturated at high volumes. This supports the scenario where the effective capacitance relates to the ion accessible ESA, and shows that the saturation of the capacitance arises from a change of ion penetration from a diffusive (at small volumes) to a non-diffusive regime at large volumes.

The water dispersion of the conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) is one of the most used material precursors in organic electronics also thanks to its industrial production. There is a growing interest for conductive polymers that could be alternative surrogates or replace PEDOT:PSS in some applications. A recent study by our group compared electrodeposited PEDOT:Nafion vs PEDOT:PSS in the use for neural recordings. Here, we introduce an easy and reproducible synthetic protocol to prepare a water dispersion of PEDOT:Nafion. The conductivity of the pristine material is on the order of 2 S cm-1 and was improved up to ?6 S cm-1 upon treatment with ethylene glycol. Faster ion transfer was assessed by electrochemical impedance spectroscopy (EIS), and, interestingly, an improved adhesion was observed for coatings of the new PEDOT:Nafion dispersion on glass substrates, even without the addition of the silane cross-linker needed for PEDOT:PSS. As proof of concept, we demonstrate the use of this novel water dispersion of PEDOT:Nafion in three different organic electronic device architectures, namely, an organic electrochemical transistor (OECT), a memristor, and an artificial synapse.

In situ atomic force microscopy (AFM) allowed us to investigate the evolution at the early stages of the growth of organic thin films. An ultrahigh-vacuum atomic force microscope, integrated with a Knudsen effusion cell for the sublimation of ?-sexithiophene (6T), continuously scans the same region during the deposition of sublimed molecules on native silicon oxide as a function of the substrate temperature. Noncontact AFM images acquired sequentially provide snapshots of the time evolution of the film morphology that is monitored up to the deposition of five monolayers. At all substrate temperatures, a Stranski-Krastanov growth mode of organic films is observed: the first two monolayers grow layer-by-layer (two-dimensional?2D), then films evolve into islands (three-dimensional?3D). Despite the apparent similarity, we find an anomalous dynamic scaling characterized by the abrupt change of the growth exponent ? vs substrate temperature. This novel transition, induced by the substrate temperature, is ascribed to the morphological transition from ziggurat islands to large terraces. The analysis of the evolution of the root-mean-square (RMS) roughness based on the distributed growth model underlines the role of down-hill mass transport for the growth of the first two monolayers, transport that is progressively hindered for the next monolayers.

Attività, dimostrazioni, exhibit e altro sul tema delle Materie Prime, dell'Economia Circolare e della Bioeconomia, proposte dagli studenti delle scuole medie e superiori al pubblico di tutte le età!

IV European Conference of RM@Schools. Raw MatTERS Ambassadors at Schools (RM@Schools) is a European project, which is elaborating strategic planning of dissemination capacity and methodology to improve the image of science & technology in schools by explaining the value of raw materials while promoting new professional careers in this sector. This project aims to involve 10 - 19 years old students in hands-on experiments and communication activities. RM@Schools started in 2016 with 6 partners. In 2018 it became the Flagship project in the Wider Society Learning segment of the EIT RawMaterials thanks to the support of the RawMaterials Academy, and in 2019 it was extended to East Europe Countries. Nowadays, the Consortium involves 28 partners from 18 EU countries and a strategic network composed of 26 Universities/ Research Centres, 60 Schools and 22 Companies. Besides, many connections are established with other European projects, which take advantage of the educational method developed by RM@Schools.

Ultrathin layers of gold, from 2 to 25 nm of nominal coverage, have been deposited on sodium-alginate biopolymer foils applying two alternative approaches: low power sputtering and thermal evaporation. The morphology of the deposited layers was obtained by means of atomic force microscopy. In the early stages of growth, thermal evaporation gives rise to a top surface resembling the underlying substrate, whereas low power sputtering produces a topography characterized by smoother areas. This indicates that the film growth occurs in different ways. X-ray photoelectron spectroscopy with two photon energies, corresponding to Al K? and Ag L? photons, was used to get information on the chemistry at the interface and on the degree of intermixing between Au and sodium-alginate. While no chemical modifications with respect to the bare materials could be detected, the evolution of the intensities of the relevant core levels of Au and sodium alginate (Au 4f and Na 1s in particular) indicated a strong intermixing in the case of films deposited by low power sputtering. This is further supported by optical measurements. The observed behaviour can be correlated with the enhanced adhesion of sputtered films compared to thermally evaporated ones.