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In this work a new Single Layer Graphene (SLG) transfer technique exploiting a hot embossing process was carried out. Flexible electrolyte gated Graphene Field Effect Transistors (G-FET) were fabricated and tested electrically. A polymeric transparent foil suitable for optics and flexible electronics, Cyclic Olefin Copolymer (COC) was used as flexible substrate. Raman characterization confirmed that the new Hot Embossing Graphene Transfer (HEGT) is suitable for the deposition of SLG and the fabrication of G-FETs. A Comparison with SLG common transfer method was carried out and proven for G-FETs fabrication. The HEGT devices showed typical characteristics and maintained the same performances when the substrate was bent. This demonstrated that the HEGT allows for efficient transfer of high quality SLG on large area thus providing the opportunity for the exploitation on a large scale production process for flexible substrates.

This work proposes a novel approach to investigate the behavior of single chamber microbial fuel cells (SCMFCs) based sensors by implementing fluid dynamic simulations to especially investigate the role of diffusion phenomena. When different flow rates are applied (i.e., 25 mL/h and 100 mL/h) the electrolyte flows differently into the cell, changing its speed and the drift-area (Adrift) in which the fluid/electrolyte is directly pushed during the drift process. Asymmetric squared SCMFCs (a-SCMFCs) ensure optimal fluid motion thanks to their architecture that maximizes the drift-area. In this work a-SCMFCs are tested as acetate bio-sensors using carbon paper and carbon felt as anodes. Experimental results show that the behavior of a-SCMFCs-based sodium acetate biosensors is strongly influenced by the morphology of both carbon felt and carbon paper-based anodes. We used fluid dynamics simulations implementing both the drift and the diffusion processes to gain new information on the behavior of carbon paper and carbon felt anodes. We especially investigated the role of their porosity, in determining the actual fluid distribution and analyte concentration inside the device, at the surface of the porous material and into its volume. We demonstrate that less porous materials, as carbon paper, are more adequate to be used in single chamber MFC-based biosensors. Indeed they can favor an optimal fluid motion, especially favoring more uniform diffusion phenomena and interaction between biofilm and surface than corrugates surfaces, as those characterizing carbon felt, resulting in a more effective analyte conversion and signal transduction.

In several biomedical applications, the detection of biomarkers demands high sensitivity, selectivity and easy-to-use devices. Organic electrochemical transistors (OECTs) represent a promising class of devices combining a minimal invasiveness and good signal transduction. However, OECTs lack of intrinsic selectivity that should be implemented by specific approaches to make them well suitable for biomedical applications. Here, we report on a biosensor in which selectivity and a high sensitivity are achieved by interfacing, in an OECT architecture, a novel gate electrode based on aptamers, Au nanoparticles and graphene hierarchically organized to optimize the final response. The fabricated biosensor performs state of the art limit of detection monitoring biomolecules, such as thrombin-with a limit of detection in the picomolar range (≤ 5 pM) and a very good selectivity even in presence of supraphysiological concentrations of Bovine Serum Albumin (BSA-1mM). These accomplishments are the final result of the gate hierarchic structure that reduces sterich indrance that could contrast the recognition events and minimizes false positive, because of the low affinity of graphene towards the physiological environment. Since our approach can be easily applied to a large variety of different biomarkers, we envisage a relevant potential for a large series of different biomedical applications.

Microbial fuel cells (MFCs) are bio-electrochemical devices able to directly transduce chemical energy, entrapped in an organic mass named fuel, into electrical energy through the metabolic activity of specific bacteria. During the last years, the employment of bio-electrochemical devices to study the wastewater derived from the food industry has attracted great interest from the scientific community. In the present work, we demonstrate the capability of exoelectrogenic bacteria used in MFCs to catalyze the oxidation reaction of honey, employed as a fuel. With the main aim to increase the proliferation of microorganisms onto the anode, engineered electrodes are proposed. Polymeric nanofibers, based on polyethylene oxide (PEO-NFs), were directly electrospun onto carbon-based material (carbon paper, CP) to obtain an optimized composite anode. The crucial role played by the CP/PEO-NFs anodes was confirmed by the increased proliferation of microorganisms compared to that reached on bare CP anodes, used as a reference material. A parameter named recovered energy (Erec) was introduced to determine the capability of bacteria to oxidize honey and was compared with the Erec obtained when sodium acetate was used as a fuel. CP/PEO-NFs anodes allowed achieving an Erec three times higher than the one reached with a bare carbon-based anode.

Two Photon Polymerization (2PP) is a powerful additive manufacturing technology already employed in the field of micro-/nano- engineering. The resolution achieved by 2PP 3D printing systems is in the range of hundreds of nanometers, but the printing volume is limited to few mm3 and printing times are not negligible. Therefore, it cannot be considered economically efficient with respect to standard clean room technologies or other Stereolitography (SL) techniques. A possible solution to this limitation is the embedding of micro-/nano- features fabricated by 2PP inside a low-resolution object obtained by SL printers. Moreover, 2PP optimized strategies should be adopted to maximize the resolution and maintain a high printing velocity. In this work, a suspended microfilter obtained by a 2PP system has been successfully integrated in a 3D printed microfluidic structure. The microchannel was fabricated by a standard SL printer using a low-cost 3D printing resin, while the suspended microfilter was obtained using a 2PP Micro-3-Dimensional Structuring System (M3D) and a drop of Femtobond D resin. An innovative printing strategy was carried out to maximize the 2PP resolution and optimize the fabrication time. In particular, the X,Y plan was exploited to build the high-resolution mesh, thus obtaining a suspended microfilter that has a final pores size of 4 μm on a considerable area of 0.5 mm2 in an only 30 min process. Finally, the microfluidic filtration system was carried out and its efficiency was evaluated employing size-controlled fluorescent microparticles.

This paper presents a critical review and the state of the art of graphene porous membranes, a brand-new technology and backdrop to discuss its potential application for efficient water desalination in low salinity water injection (LSWI). LSWI technology consists in injecting designed, adequately modified, filtered water to maximize oil production. To this end, desalination technologies already available can be further optimized, for example, via graphene membranes, to achieve greater efficiency in water-oil displacement. Theoretical and experimental applications of graphene porous membranes in water desalination have shown promising results over the last 5-6 years. Needless to say, improvements are still needed before graphene porous membranes become readily available. However, the present work simply sets out to demonstrate, at least in principle, the practical potential graphene membranes would have in hydrocarbon recovery processes.

We demonstrate the label-free and selective detection of interleukin-6 (IL-6), a key cell-signaling molecule in biology and medicine, by integrating an OECT with an immuno-affinity regenerated cellulose membrane. The objective of the membrane is to increase the local concentration of IL-6 at the sensing electrode and, thereby, enhance the device response for concentrations falling within the physiological concentration range of cytokines. The OECT gate electrode is functionalized with an oligo(ethylene glycol)-terminated self-assembled alkanethiolate monolayer (SAM) for both the immobilization of anti IL-6 antibodies and the inhibition of non-specific biomolecule binding. The OECT gate/electrolyte interface is exploited for the selective detection of IL-6 through the monitoring of antigen-antibody binding events occurring at the gate electrode.

In the study of conductive conjugated polymers, electrical doping has long played an important role. A new polymeric gas sensor has been successfully fabricated by means of an ink-jet printer using a conductive aqueous formulation of poly(3,4-ethylenedioxythiophene) poly(styrene-sulfonate) (PEDOT:PSS). A simple yet robust treatment method for the irreversible secondary doping was performed (by H2SO4 and MeOH post-treatments) to enhance conductivity and improve gas sensing performance. Real time gas sensing measurements were carried out by exposing the devices with eight different analytes in a low concentrations range of VOCs vapors up to 5 % of the saturated vapor pressure, 10 ppm of NO2 and up to 10 % of relative humidity (RH) at 21 °C, exploiting dry air as carrier and diluting gas. The gas response, obtained as the ratio between the steady-state resistance variation and the baseline resistance of the device, was evaluated for different PEDOT:PSS post-treated sensors. An unexpected behavior of PEDOT:PSS post-treated with concentrated H2SO4 was observed, while MeOH and diluted H2SO4 post-treated sensors exhibited improved response towards all investigated analytes. The best performances were obtained towards 5 % of ammonia and NO2 with a gas response of 6 % and 28 % respectively with the device post-treated with pure methanol and 16 % with the sensor post-treated with diluted sulfuric acid. Furthermore, long-term stability and the influence of temperature were evaluated on the fabricated sensors. Altogether, these promising results allow a better understanding of the secondary doping effects on the electrical and sensing properties, paving the way for electronic nose development.

Purpose In this process the electrical contact is brought to the backside of a standard silicon wafer. The details of the entire process are disclosed, from the photolithography processes to the electrodepositing step, and a model for electrical contact was designed. Design/methodology/approach The localized Cu growth of high aspect ratio (AR) microstructures was obtained through an SU-8 photolithography by exploiting the optimal adhesion on the silicon surface and the possibility of generating thick layers with a single spun process Findings The experimental results showed an unexpected behaviour that is theoretically explained in detail considering the energy band theory. The obtained geometries showed a remarkable 6:1 AR without any adhesion problem. The non-invasive front-side manipulation represents a noteworthy improvement and simplification for the design of a multi-step production process. Originality/value An alternative technological approach, called back plate electroplating, has been carried out to obtain Cu growth on the front side of a standard n-type Si wafer through a back side electrical contact. This technique was then applied to fabricate a master for hot-embossing in a LIGA (Lithographie, Galvanoformung, Abformung)-like process flow. For this purpose, an SU-8 thick mask on a standard n-doped wafer was used. Finally, by using this process, it was possible to obtain high AR Cu geometries, avoiding any complex designing and patterning of the contacts on the front side and thus ensuring good adhesion of the SU-8.

The present work describes a novel microfluidic free-flow electrophoresis device developed by applying three-dimensional (3D) printing technology to rapid prototype a low-cost chip for micro- and nanoparticle collection and analysis. Accurate reproducibility of the device design and the integration of the inlet and outlet ports with the proper tube interconnection was achieved by the additive manufacturing process. Test prints were performed to compare the glossy and the matte type of surface finish. Analyzing the surface topography of the 3D printed device, we demonstrated how the best reproducibility was obtained with the glossy device showing a 5% accuracy. The performance of the device was demonstrated by a free-flow zone electrophoresis application on micro- and nanoparticles with different dimensions, charge surfaces and fluorescent dyes by applying different separation voltages up to 55 V. Dynamic light scattering (DLS) measurements and ultraviolet&minus, visible spectroscopy (UV&minus, Vis) analysis were performed on particles collected at the outlets. The percentage of particles observed at each outlet was determined in order to demonstrate the capability of the micro free-flow electrophoresis (&micro, FFE) device to work properly in dependence of the applied electric field. In conclusion, we rapid prototyped a microfluidic device by 3D printing, which ensured micro- and nanoparticle deviation and concentration in a reduced operation volume and hence suitable for biomedical as well as pharmaceutical applications.

This work aims to show the feasibility of an innovative approach for the manufacturing of organic-based devices with a true three-dimensional and customizable structure that is made possible by plastic templates, fabricated by additive manufacturing methods, and coated by conducting organic thin films. Specifically, a three-dimensional prototype based on a polyamide structure covered by poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) using the dip-coating technique demonstrated a multifunctional character. The prototype is indeed able to operate both as a three-terminal device showing the typical response of organic electrochemical transistors (OECTs), with a higher amplification performance with respect to planar (2D) all-PEDOT:PSS OECTs, and as a two-terminal device able to efficiently implement a resistive sensing of water vaporization and perspiration, showing performances at least comparable to that of state-of-art resistive humidity sensors based on pristine PEDOT:PSS. To our knowledge, this is the first reported proof-of-concept of a true 3D structured OECT, obtained by exploiting a Selective laser sintering approach that, though simple in terms of 3D layout, paves the way for the integration of sensors based on OECTs into three-dimensional objects in various application areas.

Initially considered little more than a scientific curiosity, the family of 2D nanomaterials has become increasingly popular over the last decade [...]

Two-step hot embossing process was used to transfer graphene and to fabricate Gr/Si Schottky photodiodes. As a direct graphene transfer technique, through a hot embossing system, CVD Gr monolayer was transferred from copper foil to Cyclic Olefin Copolymer (COC) foil without PMMA sacrificial layer. Then hot embossing was employed once again to bond graphene with the prepared Si substrate to form Schottky contact. Electrical and photoelectrical characterizations have been performed to evaluate the Schottky photodiode. The photocurrent increase linearly with light intensity under 633 nm illumination. With an appropriate bias voltage, the maximum responsivity reaches 0.73 A/W. Extracted from I-V characteristics by Cheung's function, the Schottky barrier height and ideality factor are 1.01 eV and 2.66, respectively. The experimental result shows the feasibility and effectiveness of this hot embossing fabrication process, which demonstrates the opportunity for large scale production and provides a new approach for graphene optoelectronics. This is the author's peer reviewed, accepted manuscript. However, the online version of record will be different from this version once it has been copyedited and typeset.

The perspective of downscaling organic electrochemical transistors (OECTs) in the nanorange is approached by depositing poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) on electrodes with a nanogap designed and fabricated by electromigration induced break junction (EIBJ) technique. The electrical response of the fabricated devices is obtained by acquiring transfer characteristics in order to clarify the specific main characteristics of OECTs with sub-micrometer-sized active channels (nanogap-OECTs). On the basis of their electrical response to different scan times, the nanogap-OECT shows a maximum transconductance unaffected upon changing scan times in the time window from 1 s to 100 µs, meaning that fast varying signals can be easily acquired with unchanged amplifying performance. Hence, the scaling down of the channel size to the nanometer scale leads to a geometrical paradigm that minimizes effects on device response due to the cationic diffusion into the polymeric channel. A comprehensive study of these features is carried out by an electrochemical impedance spectroscopy (EIS) study, complemented by a quantitative analysis made by equivalent circuits. The propagation of a redox front into the polymer bulk due to ionic diffusion also known as the "intercalation pseudocapacitance" is identified as a limiting factor for the transduction dynamics.

A new flexible polymeric gas sensor is developed by photocrosslinking poly(ethylene glycol) diacrylate resin (PEGDA) containing multi-walled carbon nanotubes (MWCNTs) as conductive filler. The cured material shows a percolative threshold conductivity which changes when in contact with various gas analytes with different chemical and physical properties. The different behavior of the sensors toward the different gases is explained either on the basis of chemical affinity toward the polymeric matrix or due to the interactions that can occur between the analyte and the surface of the nanotubes in the case of the aromatic gas.

Herein the concomitant synthesis of a MoS2- and Cu7S4-decorated graphene aerogel is reported. The material is fully characterized and used as an active material to coat carbon fiber electrodes for the fabrication of a fiber-shaped supercapacitor. The device provides excellent capacitance values warranting stable performance even under high bending angle conditions. Moreover, a photocurable resin is selected as a smart packaging material to overcome stability problems usually affecting this class of devices. It is noteworthy that superior stability is demonstrated with a retention of almost 80% of the initial capacitance after one month. Flexible supercapacitors were also coupled with third-generation solar cells to successfully demonstrate the fabrication of wearable, portable, and integrated smart energy devices.

In this work an electrolyte gated Graphene field effect transistor (G-FET) has been developed exploiting a Hot-embossing assisted technique to transfer Single Layer Graphene (SLG) on a Cyclo Olefin Copolymer (COC) foil. An investigation on the processing and materials related effects has been carried out by a comparison with a more traditional Poly(methyl methacrylate) (PMMA) transfer approach. The fabricated G-FETs were tested as pH sensors and the electrical characteristics were investigated.

In this paper, a three-layer dielectric structure is presented as innovative unit-cell element for transmitarray (TA) antennas with enhanced bandwidth. It consists of a central layer, with a varying size square hole, used to compensate the phase of the incident field and located between two other identical layers with linearly tapered square holes, acting as matching circuits. The effectiveness of this unit-cell is demonstrated by the numerical and the experimental results here presented. As a first step, three different TAs with increasing size are designed and simulated: their 1-dB gain bandwidth, centered at 30 GHz, varies from the 30.9% of the smallest configuration, having size of 10λ0 x 10λ0, to the 17.5% of the 20λ0 x20λ0 TA. A slightly modified unit-cell is then designed, with the aim of realizing a prototype with an additive manufacturing (AM) technique. A 3D-printed dielectric TA with a size of 15.6λ0 x15.6λ0 has been manufactured and experimentally characterized. The measured prototype shows excellent performances, achieving a 1-dB gain bandwidth of 21.5%: these results prove the enhanced features of the introduced unit-cell and demonstrate the TA feasibility with AM techniques.

Additive manufacturing techniques using three dimensional (3D) printing have been shown to be suitable for a wide range of applications. In this study, stereolithography (SLA) is applied to the field of microfluidic fabrication of lab-on-a-chip (LOC) devices. LOCs deal with different milli/microsized channels and chambers, which are the key features of the devices, so an appropriate manufacturing process should provide high precision as well as high versatility. In this work, the goal was to overcome the common drawbacks of 3D printing and multistep processes, by implementing multiple polymeric materials in the same printing process. Using a customized SLA machine, a novel process was developed to print microfluidic channels enclosed between two poly(methyl methacrylate) layers in a sandwichlike structure. For microfluidic walls, two distinct commercial resins with different properties were used. Once thermal and pressure resistance of the obtained LOCs were assessed, deoxyribose nucleic acid was amplified by polymerase chain reaction inside the microfluidic chambers. Test results indicated favorable mechanical and thermal resistance, as well as chemical compatibility with the assay reagents. Such observations suggest that this novel approach can be applied to 3D printing of customized microfluidics with embedded features.

A reliable clinical assay based on circulating microRNAs (miRNAs) as biomarkers is highly required. Microdevices offer an attractive solution as a fast and inexpensive way of concentrating these biomarkers from a low sample volume. A previously developed polydimethylsiloxane (PDMS) microdevice able to purify and detect circulating miRNAs was here optimized. The optimization of the morphological and chemical surface properties by nanopatterning and functionalization is presented. Surfaces were firstly characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), fluorescamine assay and s-SDTB (sulphosuccinimidyl-4-o-(4,4-dimethoxytrityl) butyrate) assay and subsequently tested for their capacity to adsorb a fluorescent miRNA. From our analysis, modification of surface charge with 0.1% APTMS ((3-Aminopropyl)trimethoxysilane) and 0.9% PEG-s (2-[Methoxy-(polyethyleneoxy)propyl]trimethoxysilane) performed at 60 °C for 10 min was identified as the best purification condition. Our optimized microdevice integrated with real-time PCR detection, was demonstrated to selectively purify both synthetic and natural circulating miRNAs with a sensitivity of 0.01 pM.

A microfluidic platform for cell motility analysis in a three-dimensional environment is presented. The microfluidic device is designed to study migration of both single cells and cell spheroids, in particular under spatially and temporally controlled chemical stimuli. A layout based on a central microchannel confined by micropillars and two lateral reservoirs was selected as the most effective. The microfluidics have an internal height of 350 mu m to accommodate cell spheroids of a considerable size. The chip is fabricated using well-established micromachining techniques, by obtaining the polydimethylsiloxane replica from a Si/SU-8 master. The chip is then bonded on a 170-mu m-thick microscope glass slide to allow high spatial resolution live microscopy. In order to allow the cost-effective and highly repeatable production of chips with high aspect ratio (5:1) micropillars, specific design and fabrication processes were optimized. This design permits spatial confinement of the gel where cells are grown, the creation of a stable gel-liquid interface and the formation of a diffusive gradient of a chemoattractant (>48 h). The chip accomplishes both the tasks of a microfluidic bioreactor system and a cell analysis platform avoiding critical handling of the sample. The experimental fluidic tests confirm the easy handling of the chip and in particular the effectiveness of the micropillars to separate the Matrigel T from the culture media. Experimental tests of (i) the stability of the gradient, (ii) the biocompatibility and (iii) the suitability for microscopy are presented.

In-liquid biosensing is the new frontier of health and environment monitoring. A growing number of analytes and biomarkers of interest correlated to different diseases have been found, and the miniaturized devices belonging to the class of biosensors represent an accurate and cost-effective solution to obtaining their recognition. In this study, we investigate the effect of the solvent and of the substrate modification on thin films of organic semiconductor Poly(3-hexylthiophene) (P3HT) in order to improve the stability and electrical properties of an Electrolyte Gated Organic Field Effect Transistor (EGOFET) biosensor. The studied surface is the relevant interface between the P3HT and the electrolyte acting as gate dielectric for in-liquid detection of an analyte. Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS) characterizations were employed to study the effect of two solvents (toluene and 1,2-dichlorobenzene) and of a commercial adhesion promoter (Ti Prime) on the morphological structure and electronic properties of P3HT film. Combining the results from these surface characterizations with electrical measurements, we investigate the changes on the EGOFET performances and stability in deionized (DI) water with an Ag/AgCl gate electrode.

Graphene and 2D materials have been exploited in a growing number of applications and the quality of the deposited layer has been found to be a critical issue for the functionality of the developed devices. Particularly, Chemical Vapor Deposition (CVD) of high quality graphene should be preserved without defects also in the subsequent processes of transferring and patterning. In this work, a lift-off assisted patterning process of Few Layer Graphene (FLG) has been developed to obtain a significant simplification of the whole transferring method and a conformal growth on micrometre size features. The process is based on the lift-off of the catalyst seed layer prior to the FLG deposition. Starting from a SiO2 finished Silicon substrate, a photolithographic step has been carried out to define the micro patterns, then an evaporation of Pt thin film on Al2O3 adhesion layer has been performed. Subsequently, the Pt/Al2O3 lift-off step has been attained using a dimethyl sulfoxide (DMSO) bath. The FLG was grown directly on the patterned Pt seed layer by Chemical Vapor Deposition (CVD). Raman spectroscopy was applied on the patterned area in order to investigate the quality of the obtained graphene. Following the novel lift-off assisted patterning technique a minimization of the de-wetting phenomenon for temperatures up to 1000 &deg, C was achieved and micropatterns, down to 10 &micro, m, were easily covered with a high quality FLG.

Stereolithography 3D printing is today recognized as an effective rapid prototyping technique in the field of polymeric materials, which represents both the strengths and the weaknesses of this technique. The strengths relate to their easy handling and the low energy required for processing, which allow for the production of structures down to the sub-micrometric scale. The weaknesses are a result of the relatively poor mechanical properties. Unfortunately, the choice of the right material is not sufficient, as the printing parameters also play a crucial role. For this reason, it is important to deepen and clarify the effect of different printing conditions on final product characteristics. In this paper, the behavior of commercial Standard Blend (ST Blend) acrylic resin printed with stereolithography (SL) apparatus is reported, investigating the influence of printing parameters on both the tensile properties of the printed parts and the build accuracy. Twenty-four samples were printed under different printing conditions, then dimensional analyses and tensile tests were performed. It was possible to find out the optimum printing setup to obtain the best result in terms of mechanical resistance and printing accuracy for this kind of resin. Finally, a micrometric spring was printed under the optimal conditions to demonstrate the possibility of printing accurate and tiny parts with the commercial and inexpensive STBlend resin.

In the sensors field the active sensing material frequently needs a controlled temperature in order to work properly. In microsystems technology, micro-machined hotplates represent a platform consisting of a thin suspended membrane where the sensing material can be deposited, usually integrating electrical stimuli and temperature readout. The micro-hotplate ensures a series of advantages such as miniaturized size, fast response, high sensitivity, low power consumption and selectivity for chemical sensing. This work compares the coplanar and the buried approach for the micro-hotplate heaters design with the aim to optimize the fabrication process and to propose a guideline for the choice of the suitable design with respect to the applications. In particular, robust Finite Element Method (FEM) models are set up in order to predict the electrical and thermal behavior of the micro-hotplates. The multiphysics approach used for the simulation allows to match as close as possible the actual device to the predictive model: geometries, materials, physics have been carefully linked to the fabricated devices to obtain the best possible accuracy. The materials involved in the fabrication process are accurately selected in order to improve the yield of the process and the performance of the devices. The fabricated micro-hotplates are able to warm the active region up to 400 °C (with a corresponding power consumption equal to 250 mW @ 400 °C) with a uniform temperature distribution in the buried micro-hotplate and a controlled temperature gradient in the coplanar one. A response time of about 70 ms was obtained on the virtual model, which perfectly agrees with the one measured on the fabricated device. Besides morphological, electrical and thermal characterizations, this work includes reliability tests in static and dynamic modes.

In this paper, an innovative process flow developed to improve the thermal resistance of power ICs was presented. In this field, one of the major device failure mechanisms is related to the high temperatures reached during the working cycles due to the extremely critical electrical current densities. Therefore, heat transfer and dissipation are crucial aspects that need continuous improvements. Usual approaches to face this issue deal with package heat sinks design, solder selection, and wafer thinning. In this paper, a novel technological approach was settled, in which heat sinks microstructures were successfully integrated at wafer level stage on standard p-i-n diodes. To this aim, the bulk Si on the backside was partially replaced with Cu, a material characterized by a higher thermal conductivity material. Moreover, the well microstructures filled by Cu provide the advantage of wafer self-support, without requiring dedicated and more expensive thinning and handling technologies. An extensive characterization of the final devices was also carried out to evaluate the process and the thermal and electrical improvements. Finally, a failure analysis on selected devices was performed to identify any critical issue with the standard packaging process.

none 14 si Biorecognition is a central event in biological processes in the living systems that is also widely exploited in technological and health applications. We demonstrate that the Electrolyte Gated Organic Field Effect Transistor (EGOFET) is an ultrasensitive and specific device that allows us to quantitatively assess the thermodynamics of biomolecular recognition between a human antibody and its antigen, namely, the inflammatory cytokine TNFα at the solid/liquid interface. The EGOFET biosensor exhibits a superexponential response at TNFα concentration below 1 nM with a minimum detection level of 100 pM. The sensitivity of the device depends on the analyte concentration, reaching a maximum in the range of clinically relevant TNFα concentrations when the EGOFET is operated in the subthreshold regime. At concentrations greater than 1 nM the response scales linearly with the concentration. The sensitivity and the dynamic range are both modulated by the gate voltage. These results are explained by establishing the correlation between the sensitivity and the density of states (DOS) of the organic semiconductor. Then, the superexponential response arises from the energy-dependence of the tail of the DOS of the HOMO level. From the gate voltage-dependent response, we extract the binding constant, as well as the changes of the surface charge and the effective capacitance accompanying biorecognition at the electrode surface. Finally, we demonstrate the detection of TNFα in human-plasma derived samples as an example for point-of-care application. Berto, Marcello; Casalini, Stefano; Di Lauro, Michele; Marasso, Simone L; Cocuzza, Matteo; Perrone, Denis; Pinti, Marcello; Cossarizza, Andrea; Pirri, Candido F; Simon, Daniel T; Berggren, Magnus; Zerbetto, Francesco; Bortolotti, Carlo A; Biscarini, Fabio Berto, Marcello; Casalini, Stefano; Di Lauro, Michele; Marasso, Simone L; Cocuzza, Matteo; Perrone, Denis; Pinti, Marcello; Cossarizza, Andrea; Pirri, Candido F; Simon, Daniel T; Berggren, Magnus; Zerbetto, Francesco; Bortolotti, Carlo A; Biscarini, Fabio

This article reports on the heat transfer characteristics of columnar, vertically aligned, multiwall carbon nanotubes grown on a patterned Si surface. In the first part, we describe the procedure for patterning the silicon (Si) surface and the growth of multiwall carbon nanotubes (MWCNTs) on these patterned surfaces. The diameter of MWCNTs grown by chemical vapor deposition technique was in the range of 30–80 nm. In the second part, structures mimicking macroscopic finned heat sinks are used for enhancing forced convective heat transfer on a silicon substrate. Convective heat transfer coefficient has been experimentally measured for silicon substrates with and without MWCNT-based fins on it. The configuration with MWCNTs based fins shows an enhancement in convective heat transfer of 40% and 20%, as maximum and average value, respectively, compared to the bare silicon. Experiments have been carried out in a wind tunnel with air as coolant in fully turbulent regime. These encouraging results and the possibi...