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An integrated full polymeric sensing platform composed by a self-assembled bottle microresonators packaged with planar waveguide in a stable structure is presented. Microbottles made of SU-8 resist and NOA resins have been fabricated and characterized. The interrogation system is constituted by evanescently coupled planar waveguide fabricated in SU-8 on polymethyl methacrylate substrate. A simple and effective method for the packaging of the microbottle has been adopted. It provides high mechanical stability to avoid surrounding disturbance able to affect the coupling efficiency between the resonator and the waveguide. The choice of polymers as fabrication material enables the use of this method for low-cost lab-on-chip production. The viability of the platform has been demonstrated via refractometric sensing establishing a bulk sensitivity of 120 nm per refractive index unit.

Coating of high-Q whispering gallery mode micro-resonators is typically performed in order to add the functionalities of the coating material to the unique properties of this type of resonators. Silica microspheres or microtoroids are typically used as high-Q cavity substrate on which a functional film is deposited. In order to effectively exploit the coating properties a critical step is the efficient excitation of WGMs mainly contained inside the deposited layer. We developed a simple method able to assess whether or not these modes are selectively excited. The method is based on monitoring the thermal shift of the excited resonance, which uniquely depends on the thermo-optic coefficient and on the thermal expansion coefficient of the material in which the mode is embedded. We applied this technique to the case of a SU-8 layer deposited on a silica microsphere. Main tests were performed around the wavelength of 770 nm because of potential application in biochemical sensing requiring low light absorption in aqueous environment. We show that by using integrated waveguides made with SU-8 polymer (rather than silica fiber tapers) we can fulfill the proper phase matching conditions thus exciting the fundamental WGM mainly confined in the coating. A further proof of the validity of the approach is obtained assessing the free spectral range of the excited modes which depends on the refractive index of the material in which the mode is confined.

A multifunctional lab-on-a-chip platform for spectroscopic analysis of liquid samples based on an optofluidic jet waveguide is reported. The optofluidic detection scheme is achieved through the total internal reflection arising in a liquid jet of only 150 mu m diameter, leading to highly efficient signal excitation and collection. This results in an optofluidic chip with an alignment-free spectroscopic detection scheme, which avoids any background from the sample container. This platform has been designed for multiwavelength fluorescence and Raman spectroscopy. The chip integrates a recirculation system that reduces the required sample volume. The evaluation of the device performance has been accomplished by means of fluorescence measurements performed on eosin Y in water solutions, achieving a limit of detection of 33 pM. The sensor has been applied in Raman spectroscopy of water-ethanol solutions, leading to a limit of detection of 0.18%. As additional application, analysis of riboflavin using fluorescence detection demonstrates the possibility of detecting this vitamin at the 560 pM level (0.21 ng l(-1)). Although measurements have been performed by means of a compact and low-cost spectrometer, in both cases the microjet optofluidic chip achieved similar performances if not better than high-end benchtop based laboratory equipment. This approach paves the way towards portable lab-on-a-chip devices for high sensitivity environmental and biochemical sensing, using optical spectroscopy.

Whispering Gallery Mode (WGM) micro-resonators like microspheres or microtoroids are typically used as high-Q cavity substrate on which a functional film coating is deposited. In order to exploit the coating properties a critical step is the efficient excitation of WGMs mainly contained inside the deposited layer. We developed a simple method able to assess whether or not these modes are selectively excited. The method is based on monitoring the thermal shift of the excited resonance, which uniquely depends on the thermo-optic coefficient and on the thermal expansion coefficient of the material in which the mode is embedded.

We developed a biophotonic ring resonators for label-free biosensing. We first study an optimization approach for improving the optical performance of Su-8 based ring resonator. The effects of an ultrathin Su-8 under-layer are evaluated in terms of quality factor. An improvement of about 20% is obtained, as a consequence of the improved polymeric affinity between the substrate and the ring material. The biophotonic device is, than, integrated with polydimethylsiloxane (PDMS) microfluidic channel for biomolecule detection. The experimental results indicated that the ring resonators are able to detect the biomolecules of bovine serum albumin (BSA) after their immobilization on the Su-8 surface.

An all polymeric platform based on planar microring resonator employing a microfluidic flow-through approach is presented and exploited for biosensing applications. A micromilled hole in the center of the microring resonator drives the analyte flow towards the sensing surface, so optimizing the transport kinetic. A simulated and experimental evaluation of the improved performances in terms of kinetic transport and response time is also presented. Biosensing experiments with bovine serum albumin (BSA) based solutions at different concentrations are performed. Optical characterizations by resonance peak shift show a linear behaviour up to 200 nM and a saturation condition at higher concentrations in SU-8 based microring resonators. A reduction of more than 4 times of the response times, as compared with the standard flow-over approach, is obtained with the proposed flow-through approach. The proposed sensing architecture, allowing the single addressing of ring resonator, gives numerous advantages related to time responses and multiplexing of different analytes for a label-free biosensing.

Infectious diseases and sepsis, as a severe and potential medical condition in which the immune system overreacts and finally turns against itself, are a worldwide problem. As a matter of fact, it is considered the main cause of mortality in intensive care. For such a pathology, a timely diagnosis is essential, since it has been shown that each hour of delay in the administration of an effective pharmacological treatment increases the mortality rate of 7%. Therefore, the advent of a POCT platform for sepsis is highly requested by physicians. Biomarkers have gained importance for the diagnosis and treatment monitoring of septic patients, since biomarkers can indicate the severity of sepsis and can differentiate bacterial from viral and fungal infection, and systemic sepsis from local infection. The present paper deals with the development of fluorescence-based bioassays for the sepsis biomarkers and their integration on a multianalyte chip. Among the different biomarker candidates, the attention was focused on procalcitonin (PCT), C-reactive protein (CRP) and interleukine-6 (IL-6) as well as on soluble urokinase plasminogen activator receptor (suPAR) recently proposed as a very effective inflammatory marker, potentially capable of acting also as a prognostic biomarker. Starting point of this new setup was an already developed fluorescence-based optical platform, which makes use of multichannel polymethylmetacrylate chips for the detection of different bioanalytes, and the serial interrogation of the microfluidic channels of the chip. The novel proposed optical setup makes use of a suitable fluorescence excitation and detection scheme, capable of performing the simultaneous interrogation of all the channels. For the excitation part of the optical setup, a diffractive optical element is used which generates a pattern of parallel lines, for the simultaneous excitation of all the channels and for the optimization of the optical power distribution. For the detection part, an array of optical absorbing waveguides (long-pass coloured glass filters) is used, which collects the scattered light and the emitted fluorescence, filters out the excitation component, and is faced to a large area rectangular detector, for the simultaneous fluorescence detection. The implemented sandwich immunoassays comprise a capture antibody immobilized onto the surface of the chip channel and a detection antibody properly labelled with a fluorophore. Limits of detection of 2.7 ng/mL, 0.022 µg/mL, 12 ng/mL and 0,3 ng/mL were achieved for PCT CRP, IL-6 and suPAR, respectively.

The realization of a simple real time biosensor, in which antibodies are immobilized onto surfaces, represents a promising application in the immunoassay development. Among the various sensing approaches, one of the most promising is based on microring resonators, offering a lot of advantages such as mass production, reduced dimensions, label-free and real time detection. The use of the evanescent field as optical transduction principle allows the development of label-free biosensors, in which the antibody is usually immobilized on the sensor surface and the binding of the antigen can be controlled and followed in real-time. The overall performances of immunosensors are strongly related to the optimization of the immobilization process and the integration between the microfluidic parts and the optical detection system. The combination of these two aspects makes the biosensing process very efficient, with a consequent reduction of the response time and improvement of the immobilization process efficiency. In this work we explore the working mechanism of a flow-through microresonator platform. A drilled hole, in the center of the ring, allows the active transport mechanism of the analyte toward the sensing surface with a consequent reduction of the response time. Moreover, we study the effects of oxygen plasma, in terms of duration times and plasma power, on immobilization efficiency of immunoglobulin G (IgG). An improvement of about 20% of the protein adsorption is ascribed to chemico-physical modification of SU-8. The measured sensor response time in flow-through configuration is about five times shorter respect to standard flow-over configuration.

A novel therapeutic drug monitoring point of care testing (POCT) optical device for the detection of immunosuppressants in transplanted patients was designed and tested, with the body interface constituted by an intravascular microdialysis catheter (MicroEye®) which provides the dialysate as clinical sample. An optical biochip with 10 microchannels, based on total internal reflection fluorescence (TIRF), enables the frequent measurement of immunosuppressants. Heterogeneous competitive immunoassays for the detection of mycophenolic acid, tacrolimus and cyclosporine A are implemented on the different microchannels, with the derivative of the immunosuppressants immobilised on the bottom part of the micro-channels.

In recent years, microbottle resonators that support non-degenerate whispering gallery modes (WGMs), propagating by successive total internal reflections close to the resonator surface and all along its axis, have been widely investigated due to their potential applications in optical sensing, microlasers and nonlinear optics. To overcome some drawbacks of the standard silica microbottle resonators, we focused our attention on polymers such as SU-8 resist and NOA resins. A drop of polymeric material is dispensed onto a fiber stem, providing a mechanical support for the bottle resonator, and is photo-polymerized by an UV lamp. The interrogation system, usually constituted by a tapered silica fiber evanescently coupled with the microresonator, is substituted by a more stable planar waveguide realized in SU-8 by means of standard photolithography technique. Moreover, for guarantying the stability to surrounding disturbance of the coupling between the microbottle resonator and the planar waveguide, the fiber stem is glued to substrate. Two drilled holes in the substrate allow the rise of the glue at the ends of the fiber stem and the fixing of sensor on PMMA substrate. In the present work, we presented an integrated full polymeric platform with self-assembled bottle microresonators packaged in a stable structure. SU-8 and NOA based microbottles are realized and morphologically characterized. The low autofluorescence emission and long term stability make the NOA based bottles suitable to be employed in a great variety of conditions. Bulk sensing measurements are performed by using water:ethanol solutions and a bulk sensitivity of 120 nm/RIU is estimated.

The most exploited active material for photovoltaic devices is the regioregular poly(3-hexylthiophene) (P3HT), p-type conjugated polymer, blended with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), n-type material. The deposition methods and the induced morphology strongly influence the functionality of the active material and in turn the final charge generation performances of a photoactive layer. In the present work, we studied the influence of PCBM concentration on the morphological and spectroscopic properties of the inkjet printed P3HT:PCBM blends through atomic force microscopy (AFM), Raman spectroscopy and transient absorption spectroscopy. The aim is to value the charge formation yield in the blends, prepared by inkjet technology, as function of the acceptor concentrations in correlation with morphology and intermixing of the two components. For the inkjet printed samples the blends composition that corresponds to the best intermixing between P3HT and PCBM and the higher charges formation yield should be between 20% and 45% in weight (wt)., differently for what has been found previously for spin-coated samples. Indeed, for inkjet prepared film, the 45 wt.% blend ratio leads to much bigger domains with respect to the spin-coated samples as shown from the AFM measurements. © 2013 Elsevier B.V. All rights reserved.

Organic thin film phototransistor (OPTs) devices in bottom-gate/top-contact configuration were fabricated and used as analytic system to study the electrical and optical properties of pentacene. The channel of the OTFT devices was illuminated by laser radiation of wavelength 670 nm and the effect of irradiation on the electrical responses of the devices was investigated at different temperatures and incident optical powers. The photoresponse and the electrical parameters of the devices (mobility, threshold voltages and on/off ratios – ION/IOFF) were evaluated in order to investigate the relationship between the light sensing behavior of the phototransistors and their electrical performances. Moreover, the OPT's time-resolved electrical response to light irradiation was modelled to decouple the fast-varying photoexcitation effects from slow bias stress decays in order to investigate the reversibility properties, the time stability of electrical responses and the photocurrent.

In this article, we describe the development of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)-based ink for the fabrication of indium tin oxide (ITO)-free polymer solar cells (PSCs). The ink consisted of PEDOT:PSS, suitably doped with dimethyl sulfoxide (DMSO) in solution. The printed PEDOT:PSS showed electrical conductivity of 1000 S/cm and transparency around 85% in the visible range. Then, they were employed as anodes in ITO-free polymer PSCs based on a bulk heterojunction of poly(3-hexylthiophene) and [6,6]-phenyl C61-butyric acid methyl ester. The effects of surface treatments (O2 plasma, UV ozone) of glass substrates on the quality and morphology of the printed layer were investigated in order to improve the anode quality. The performances of the devices with printed polymeric anode were compared to the one realized depositing DMSO-PEDOT:PSS by spin coating technique. The best cells performances were obtained by UV ozone treatment reaching a power conversion efficiency of 1.5%. POLYM. COMPOS., 34:1493–1499, 2013. © 2013 Society of Plastics Engineers

An optical fiber fuel level sensor for aeronautical applications is developed and tested. The sensor is based on an array of total internal reflection point sensors multiplexed on a single fiber by optical couplers and simultaneously interrogated by an Optical Time Domain Reflectometry approach. Unlike conventional sensors based on total internal reflection, the new design permits to be sensitive to common jet fuels (JetA-1, JP4, JP5, JP7), and also to correctly operate when the sensor is partially or totally exposed to condensed water on the sensor surface. The sensor does not require aircraft calibration or temperature compensation. Experimental results show that an accuracy of ±1.5 mm could be achieved. The sensor is also able to measure the free water level in the fuel tank.

The realization of a simple real time biosensor, in which antibodies are immobilized onto surfaces, represents a promising application in the immunoassay development. Among the various sensing approaches, one of the most promising is based on microring resonators, offering a lot of advantages such as mass production, reduced dimensions, label-free and real time detection. The use of the evanescent field as optical transduction principle allows the development of label-free biosensors, in which the antibody is usually immobilized on the sensor surface and the binding of the antigen can be controlled and followed in real-time. The overall performances of immunosensors are strongly related to the optimization of the immobilization process and the integration between the microfluidic parts and the optical detection system. The combination of these two aspects makes the biosensing process very efficient, with a consequent reduction of the response time and improvement of the immobilization process efficiency. In this work we explore the working mechanism of a flow-through microresonator platform. A drilled hole, in the center of the ring, allows the active transport mechanism of the analyte toward the sensing surface with a consequent reduction of the response time. Moreover, we study the effects of oxygen plasma, in terms of duration times and plasma power, on immobilization efficiency of immunoglobulin G (IgG). An improvement of about 20% of the protein adsorption is ascribed to chemico-physical modification of SU-8. The measured sensor response time in flow-through configuration is about five times shorter respect to standard flow-over configuration.

Polymer micro-bottle resonators are fabricated by means of a simple self-assembling process. High optical quality SU-8 negative resist is chosen as bottle material. SU-8 is dispensed onto a fiber stem and is kept in rotation during the UV photo-polymerization. Micro-bottles with different geometrical sizes have been obtained by changing the SU-8 dispensed volume, with a repeatability of about 2%. Planar waveguides is chosen as interrogation system for our SU-8 self-assembled micro-bottle resonators. The highest quality factor Q associated to the resonance peak in the transmission spectrum is about 3.8 × 10 4 .

In the present work, we report the influence of the solvents on the morphology and the uniformity of inkjet printed n-type (electron-transporting) perylene diimide (PDI-8CN2) semiconductor films on SiO 2 substrates. In particular, a solvent mixture composed by o-dichlorobenzene and chloroform was employed and the semiconductor crystalline structure was investigated as a function of the mixing ratio of the component solvents. For each mixture composition, the printing parameters such as substrate temperature and drop overlapping degree, were optimized to improve the reproducibility of the deposition process and the structural quality of the final films. Organic thin film transistors were fabricated and electrically characterized. The electrical measurements suggest that for the devices with larger active areas, the solvent mixture approach improves the performances of OTFTs in comparison with the use of pure o-dichlorobenzene solution.

We developed and characterized inks based on dispersions of N-doped titanium dioxide (TiO2) in pol- yethylenimine (PEI)/ethanol solutions with chemicophysi- cal properties suitable for the ink-jet printing process. In detail, we prepared suspensions by varying the concentra- tion of the polymeric dispersant to investigate the effect of the dispersant on the time stability and printability of the ink. Moreover, we printed the N-doped TiO2/PEI-based inks on different substrates and studied as the substrate temperature and the printing parameters influenced the printed product quality. Furthermore, the optical proper- ties and the morphology of the printed films were also investigated. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 3630-3636, 2011

The inkjet printing (IJP) technique is gener- ally used as tool for positioning small quantities of a liquid material on a target substrate. An interesting application of IJP is inkjet etching that consists of the deposition of drops of solvent or solvent mixtures onto a soluble polymer layer. This technique allows one to structure the polymer film and to change the shape, from concave to convex, by varying the mixing ratio of the solvents. In this work, the structuring of some polymeric layers (polyimide and poly- styrene) by solvents (N-methyl-2-pyrrolidone (NMP) and toluene (TOL)) and a solvent mixture (TOL-NMP) at different mixing ratios were studied, and the effect of the printing parameters on the microstructural profile was investigated. Some applications in optoelectronic devices are described. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 3637-3643, 2011

Received 28 April 2011; accepted 28 April 2011DOI 10.1002/app.34777Published online 11 August 2011 in Wiley Online Library (wileyonlinelibrary.com).ABSTRACT: Volatile organic compound (VOC) chemicalsensors increasingly rely on the use of polymer nanocompo-sites (PNCs) as sensing materials, thanks to the simpleprocessability of polymers combined with the conductivityproperties of nanoparticles dispersed in an insulating poly-mer matrix. Recently, inkjet printing (IJP), the main advantageof which is its patterning capability, was proven to be areliable technique for the deposition of these materials. In thiswork, PNC chemical sensors were fabricated by IJP of apolystyrene/carbon black based ink. The sensor responseswere measured upon exposure to acetone vapors andanalyzed as function of the sensitive material geometry.Among the different realized geometries, the lines transverseto the interdigitated electrodes fingers resulted in the optimalconfiguration for the sensing layer in a VOC chemical sensor.

Transparent and conductive nanocomposite films were spin-coated with the use of undoped and di- methyl sulfoxide (DMSO)-doped polyaniline (PANI)- poly(styrene sulfonate) (PSS) dispersions. The prepared dispersions were investigated in terms of their nanopar- ticle size distributions, and the corresponding films were morphologically, optically, and electrically characterized. These films were used as hole-injection layers (HILs) in or- ganic light-emitting diode (OLEDs), and the device per- formances were compared to a reference device without an HIL. The device based on the PANI-PSS layer showed the best electrooptical characteristics, lowest switch-on voltage, and improved efficiency. In particular, the device efficiency grew about three times with the introduction of the PANI-PSS layer (1.20 Cd/A) and about two times with the introduction of the DMSO-doped PANI-PSS film (0.77 Cd/A) compared to an OLED without an HIL (0.4 Cd/A). These results indicate that the device with the undoped PANI-PSS was the more suitable one to be used as an HIL in an OLED device. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 3618-3623, 2011

When dealing with transplanted patient treatment, therapeutic drug monitoring (TDM) represents one of the most crucial aspects for the individualization of the correct dosage of immunosuppressants, in order to ensure an appropriate medical treatment and avoid the rejection of the transplanted organ. A new Total Internal Reflection Fluorescence (TIRF) based optical biochip for the detection of immunosuppressants in transplanted patients and suitable for point of care testing (POCT) was designed. As first integration of a binding inhibition immunoassay with the optical biochip, a mycophenolic acid assay was performed on the prototype chip.

Soluble urokinase plasminogen activator receptor (suPAR) is an inflammatory protein present in blood and a marker of disease presence, severity and prognosis. A heterogeneous sandwich assay is proposed for quantifying suPAR by employing a capture antibody from rat and a biotinylated detection antibody from mouse. Optical detection was achieved by a successive exposure of the biotinylated sandwich to streptavidin labelled with ATTO647N. The heterogeneous assay was implemented on a multichannel polymethylmetacrylate (PMMA) optical biochip, potentially capable of the simultaneous detection of more than one analyte. Capture antibody was immobilized on the PMMA surface of the microfluidic channel and the assay was performed with the following protocol: i) surface blocking with BSA, ii) incubation with suPAR or PBS, iii) incubation with biotinylated suPAR detection Ab and iv) incubation with streptavidin-ATTO647N. Promising preliminary results were obtained with this protocol. Moreover, an improved optical setup is proposed which avoids the mechanical scanning of the chip and consequently the in-series fluorescence excitation and read out, allowing the simultaneous measurement of the fluorescence on all the channels of the microfluidic chip.

In the present work an optimization study on the performances of polymeric ring resonator is reported. An embedded structure, characterized by the presence of an under and upper layer of Su-8 2002, is chosen in order to improve the optical performances, in terms of quality factor and extinction ratio. Specific combinations of Su-8 2002 diluted in cyclopentanone are tested as under-layer in single mode ring resonators. Morphological analysis indicated that the employment of Su-8 with 3% solid content increases the quality factor of about 20% respect to the standard structure. Moreover, the employment of a spin-coated Su-8 upper-layer increases the optical performances of about 50% due to a reduction of the surface roughness, intrinsic of photolithographic process.

A novel fuel level sensor for aeronautical applications is developed. The sensor is based on an array of total internal reflection (TIR) point sensors. Respect to conventional TIR sensors the new design permits to be sensitive to common jet fuels (JetA, JP4,JP7) but also to operate with new alternative fuels. The sensor doesn’t require aircraft calibration, temperature compensation and furthermore is able to operate correctly when partially or totally exposed to presence of condensed water on its surface. The point sensors are multiplexed on a single fiber by optical couplers and interrogated simultaneously by Optical Time Domain Reflectometry (OTDR) at a wavelength of 1550nm. Experimental results show a resolution of ±1.5mm could be achieved. The sensors is also able to measure the free water level in the fuel.

Microring resonators are emerging as promising building blocks of integrated optics thanks to their versatility in different research fields, such as telecommunication, biosensing and environmental protection and monitoring [1-3]. The small device sizes and the easy of fabrication, with conventional lithographic techniques, make them ideal for large scale integration. A novel fabrication approach include the employment of polymeric materials, for both the substrate and the sensing element, instead of the traditional silicon. The low costs, the high flexibility and ease structuring with micromilling machines makes the polymer materials very attractive for the fabrication of sensing platforms [4-5]. Many efforts were made to optimize the transport kinetic of the analyte under test to the sensing area in order to reduce both detection time and limit of detection. The most interesting method, investigated mainly for suspended nanohole arrays, is based onto "flow through" approach. In that case, the analyte is flowing orthogonally to the sensor surface, so ensuring higher transfer rate respect to standard "flow-over" approach, in which the analyte flows along the surface [6]. In the present work, we developed a novel microring architecture based onto flow-through approach with a fully integrated microfluidic. Su-8 based microring resonators were fabricated on to PMMA substrate with a direct laser writing technique. A drilled hole is realized in the center of the microring resonators by means of a micromilling machine. The biomolecule sensing capability is studied by employing bovine serum albumin (BSA) protein. The sensor response time is evaluated in both in flow-over and flow-through approach, as reported in figure 1. An improvement of about four times of the sensor response time is observed for flow-through approach respect to flow-over, so indicating a better transport kinetic for a real- time detection

In the hospital Intensive Care Units (ICU) there is an even greater demand by the physicians for the continuous immunosuppressant drug monitoring in the transplanted patient therapy, in order to avoid different risks and diseases which may occur as result of some drug dosage related effect, such the rejection crisis or sepsis. Here we present a novel design of a point of care testing (POCT) device for the drug dose--adjustment in this kind of patients. The working principle of the device will be discussed. Preliminary tests on the immunoassay strategies for immunosuppressant drugs recognition such as on the optical chip realization and characterization are reported.

The investigation of a simple and self-assembling method for realizing polymeric micro-bottle resonators is reported. By dispensing precise amounts of SU-8 onto a cleaved optical fiber, employed as mechanical support, bottle microcavities with different shapes and diameters are fabricated. The balancing of surface energy between glass fiber and polymeric microresonator with surface tension of SU-8 confers different shape to these microstructures. Planar single-mode SU-8 based waveguide, realized on polymethylmethacrylate, is chosen for exciting the micro-bottle resonators by evanescent wave. The reliability of the fabrication process and the shape of the bottle microcavities are investigated through optical analysis. We observe whispering gallery modes in these resonant microstructures by a robust coupling with single mode planar waveguides around 1.5 μm wavelength. The resonance spectra of micro-bottle resonators and the spectral characteristics, such as Quality-factor (Q factor) and free spectral range, are evaluated for all the realized microstructures. SU-8 micro-bottle resonators show high Q-factors up to 3.8 × 104 and present a good mechanical stability. These features make these microcavities attractive for sensing and/or lasing applications in a planar platform.

A novel optical biochip for immunosuppressants detection in transplanted patients is described. The optical working of the chip, based on total internal reflection fluorescence and consisting of two bonded polymeric parts, a Zeonex 330 slide and a Topas foil was demonstrated. In parallel, a heterogeneous competitive immunoassay for tacrolimus was implemented using a thirteen- microchannel optical chip interrogated by an in-house optical platform based on fluorescence anisotropy and the bioassay conditions were optimized: a limit of detection of 0.11 ng/mL, a limit of quantification of 0.57 ng/mL and a coefficient of variation of 25% were achieved.

In this work we present a direct printing of microlenses using high viscous polymer materials. In particular the pyro-electric effect activated onto a Lithium Niobate crystal is exploited for the fabrication on demand of microlens array. © 2014 AEIT.

Recently, great interest has been devoted to cost-effective alternative energy sources such as organic solar cells because of the mechanical flexibility and the versatility of chemical structure, the low cost of fabrication, and ease of processing. As regards this last point, the possibility to deposit organic materials from solutions at low temperatures makes them employable for fabricating printed solar cells by direct printing methods. In this study, we used the inkjet-printing technology to deposit P3HT blends with various fullerene acceptors ([60]PCBM, [70]PCBM and bis[60]PCBM) dissolved in single solvents, 1,2-dichlorobenzene (DCB) and chlorobenzene (CB), and their mixtures. After optimizing the printing parameters (printhead speed, drop emission frequency, and substrate temperature), the effect of the solvents on the morphology of the photoactive layers was analyzed through Raman spectroscopy and atomic force microscopy. Polymer solar cells with the structure glass/ITO/PEDOT:PSS/blend/Ca/Al were fabricated and characterized by current-voltage (I-V) measurements under 100 mW/cm2 AM 1.5G illumination. A comparative study of the performances of the devices was performed based on three different fullerene derivatives, correlating them to the microstructure of the printed blend films. The optimal devices were obtained when the blend films were deposited from a mixture of DCB:CB 4:1 by volume: this was in agreement with the most favorable morphology of these films. © 2012 Springer Science+Business Media.

In the present work, the pyro-electrohydrodynamic technique was used for the realization of tunable-size microlens arrays. Poly(methyl methacrylate) dissolved in different solvent mixtures was used as the polymeric material for the realization of the microstructures. By controlling the experimental parameters and in particular, the volume of the drop reservoir, graded-size square arrays of tens of microlenses with focal length in the range 1.5-3 mm were produced. Moreover, the optical quality and geometrical features were investigated by profilometric and interferometric analysis. (C) 2013 Optical Society of America

In the present work, the transport mechanism of organic transistors with bottom-gate/top-contact structure, manufactured by employing traditional and inkjet printing techniques, was studied. Poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) conductive polymer was used for realizing printed source, drain and gate electrodes. The influence of the printing parameters (substrate temperature, drop overlapping degree, drop emission frequency) on the uniformity and morphology of the PEDOT:PSS layer was investigated. Polymethyl methacrylate (PMMA) was used as organic dielectric and pentacene, deposited by thermal evaporation, was employed as p-type semiconductor. Organic field effect transistors (OFETs) were fabricated and electrically characterized before and after the thermal annealing process at 120 °C for 1 h in nitrogen ambient. The effect of the annealing on the performances of the OFETs was investigated by modelling the measured electrical characteristics and analyzing them in terms of mobility, characteristic temperature and energy distribution of the density of localized states (DOS). In addition, the OFET working under electrical stress in ambient conditions was observed and discussed. Copyright © 2013 American Scientific Publishers All rights reserved.

Here the pyroelectric functionality of a Lithium Niobate (LN) substrate is used for non-contact manipulation of liquids. In this work we introduced the use of a pyro-electrohydrodynamc (PEHD) dispenser for the manipulation of high viscous polymer materials leading to the fabrication of arrays of microlenses. The set-up used for the experiment is described and the fabricated microlenses are analyzed by means of the Digital Holography (DH) set-up in transmission mode and through profilometric analysis. PMMA based ink was employed for the realization of optical quality microsctructures whose geometrical properties and, hence, the focal lengths were controlled by modifying the printing configuration of the PEHD method. The profilometric results are in agreement with those calculated using the digital holography technique.

High conductive and transparent nanocomposite films consisting of poly(3,4-ethylenedioxythiphene):poly(4-styrenesulfonate) (PEDOT:PSS) doped with dimethyl sulfoxide (DMSO) and double-walled carbon nanotubes functionalized with carboxylic groups (c-DWCNTs) were spin-coated and their electrical (four-point measurement), optical (UV-Vis spectroscopy), morphological (SEM, AFM) and structural (Raman) properties were investigated. Thin films of c-DWCNT/DMSO-PEDOT:PSS resulted more conductive (950 S/cm) in comparison with the pristine DMSOPEDOT: PSS films (700 S/cm).

Actually the most promising polymer solar cell architecture utilizes ITO as transparent conductve anodic electrode. The limited flexibility of ITO and the increasing cost of indium make this kind of electrode not desirable for realizations of low-cost and flexible solar cells. For this reason, it is necessary to develop low-cost, highly flexible and transparent electrodes that can replace the widely used ITO. In this paper, we investigated a new commercial dispersion of PEDOT:PSS suitably modified with dimethyl sulfoxide in solution in order to obtain a highly transparent and conductive manufactured film (HC-PEDOT:PSS) by inkjet printing.

Metal-insulator-semiconductor (MIS) capacitors based on pentacene semiconductor and CYTOP polymeric dielectric were realized and characterized by capacitance-frequency measurements (C-F) under dark and light conditions at different aging times. The devices showed good responses under light radiation at zero time and a strong degradation of the performances during the time due to a modification of the impedance of the dielectric layer.

Recently, the inkjet printing (IJP) technology was advised as a direct method for the fabrication of high-quality and high-precision microlenses overcoming the drawbacks of the traditional techniques which usually require multiple complex processing steps making the fabrication costly. IJP has the great advantage to be extremely versatile in definition of the patterns of microstructures to be realized employing polymers with suitable optical transmission and thermo-mechanical properties. In the present work, we reported the manufacturing of microlenses by inkjet printing Poly(methyl methacrylate) (PMMA) solutions prepared with different solvents (toluene, N-Methyl-2-pyrrolidone, chlorobenzene, ortho-dichlorobenzene) and solvent mixtures at different mixing ratios and investigated the effects of these parameters on the shape and the geometry of the microstructures. These structures were analyzed by means of interferometric Mach- Zehnder technique in confocal configuration and the wave aberrations were evaluated. The results showed the feasibility of manufacturing microlenses via IJP with diameters ranging from 40 to 90 μm and focal lengths of the order of magnitude of hundred micron.

Polymer nanocomposites (PNCs) represent a new class of sensing materials for volatile organic compounds (VOCs) detection. These materials can be simply processed by inkjet printing (IJP) technique, an emerging technology that has assumed a key role in the field of electronics wherever replacing conventional rigid substrates with flexible ones is required. In the present work, we fabricated PNCs chemical sensors inkjet printing a polystyrene (PS)/carbon black (CB) composite based ink on different substrates, flexible and not, such as polyethylene terephthalate (PET), glass and alumina. The sensors responses have been analyzed upon exposure to acetone organic vapors and compared in terms of sensitivity, response time and limit of detection.

The interference effects generated in a bottom-emitting electroluminescent device fabricated on a polymer underlayer introduced with the aim of improving the anode roughness have been studied. The analysis of the interference fringes at different detection angles and the spatial coherence demonstrates that this phenomenon is due to multiple internal reflections that propagate in the polymer layer. This effect can be eliminated by modifying the polymer thickness and the incidence angle of the electromagnetic radiation at the anode–polymer interface. Inkjet etching technology is adopted for microcavities-shaped polymer structuring to destroy the resonator effect of the optical cavity.

Nanocomposite films based polyaniline and polystyrene sulfonate (PANI:PSS) were prepared and characterized by chemical oxidative polymerization. Transparent and uniform films were obtained by spin‐coating onto patterned ITO‐coated glass substrates and were used as hole injection layer (HIL) in OLED devices. The devices made with HIL‐based PANI:PSS were compared with those with only ITO and showed better electrical characteristics, lower turn‐on voltage and a three time improved device efficiency.

An on-chip optofluidic sensor based on liquid jet waveguide has been developed. Laser induced fluorescence takes advantage of the waveguiding nature of a jet stream to detect, at very low detection limits, common fluorophore. Tests performed on eosin Y in water demonstrated detection at 38 pM level. The proposed approach provides high excitation and collection efficiency of the sample under analysis, avoiding, at the same time, background noise that commonly affects fluorescence spectroscopy of liquids.

The investigation of a method for fabricating microlenses by a nozzle-free inkjet printing approach is reported. The new method, based on a pyroelectrohydrodynamic mechanism, is also able to dispense viscous liquids and to draw liquid phase drops directly from the reservoir. Specifically, by dispensing optical grade polymer dissolved in different solvent mixtures, microlenses were printed with a pattern defined directly through this deposition method. The reliability of the microlenses and the tunability of their focal properties were demonstrated through profilometric and inteferometric analyses. (C) 2012 Optical Society of America