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Copper-free "click" chemistry on appropriately modified surfaces and photolithography were explored for site directed immobilization of biomolecules. The surfaces were modified either with self-assembled monolayers of silanes or an epoxy resin and then used as they were or further modified through adsorption of rabbit gammaglobulins to increase their reactive amine-content. All surfaces were then reacted with a succinimidyl ester cyclooctyne derivative and the efficiency of each modification approach was determined through click reaction with an azide derivative of fluorescein. It was found that the highest fluorescence signal was provided by the surface that had been modified with the epoxy resin and then coated with rabbit gamma-globulins. Surfaces prepared following the different modification procedures have been analyzed with ToF-SIMS to gain insight into the chemical changes of the surfaces after each step of the modification procedure. Analysis of intensities of characteristic ions signals confirmed the successful outcome of click reaction following the proposed surface modification approach. In addition, the ability to define through photolithography areas for site-directed immobilization of biomolecules onto surfaces modified with the succinimidyl ester cyclooctyne derivative was demonstrated through the creation of two molecules patterns.

Two types of preformed alginate wet gels, one with a low (30–35%) and the other with a high (65–75%) content of glucuronic acid, were reacted with an aliphatic triisocyanate that was priorly allowe...

Surfaces for guided cell adhesion and growth are indispensable in several diagnostic and therapeutic applications. Towards this direction, four diblock copolymers comprising polyethylene glycol (PEG) and poly(2-tetrahydropyranyl methacrylate) (PTHPMA) are synthesized employing PEG macroinitiators of different chain lengths. The copolymer with a 5000 Da PEG block and a PEG-PTHPMA comonomers weight ratio of 43-57 provides a film with the highest stability in the culture medium and the strongest cell repellent properties. This copolymer is used to develop a positive photolithographic material and create stripe patterns onto silicon substrates. The highest selectivity regarding smooth muscle cell adhesion and growth and the highest fidelity of adhered cells for up to 3 days in culture is achieved for stripe patterns with widths between 25 and 27.5 µm. Smooth muscle cells cultured on such patterned substrates exhibit a decrease in their proliferation rate and nucleus area and an increase in their major axis length, compared to the cells cultured onto non-patterned substrates. These alterations are indicative of the adoption of a contractile rather than a synthetic phenotype of the smooth muscle cells grown onto the patterned substrates and demonstrate the potential of the novel photolithographic material and patterning method for guided cell adhesion and growth.

Molecules near surfaces are regularly trapped in small cavitations. Molecular confinement, especially water confinement, shows intriguing and unexpected behavior including surface entropy adjustment, nevertheless, observations of entropic variation during molecular confinement are scarce. An experimental assessment of the correlation between surface strain and entropy during molecular confinement in tiny crevices is difficult because strain variances fall in the nanometer scale. In this work, entropic variations during water confinement in 2D nano/micro cavitations were observed. Experimental results and random walk simulations of water molecules inside different size nanocavitations show that the mean escaping time of molecular water from nanocavities largely deviates from the mean collision time of water molecules near surfaces, crafted by 157 nm vacuum ultraviolet laser light on polyacrylamide matrixes. The mean escape time distribution of a few molecules indicates a non-thermal equilibrium state inside the cavity. The time differentiation inside and outside nanocavities reveals an additional state of ordered arrangements between nanocavities and molecular water ensembles of fixed molecular length near the surface. The configured number of microstates correctly counts for the experimental surface entropy deviation during molecular water confinement. The methodology has the potential to identify confined water molecules in nanocavities with life science importance.

The patterning of organic materials on solid substrate surfaces has been demonstrated by several methods, such as photolithography, soft lithography, imprint lithography and ink-jet printing. Fluorinated polymers and solvents provide attractive material systems to develop new patterning approaches, as they are chemically orthogonal to non-fluorinated organic molecules, allowing their efficient incorporation in different devices and systems. Moreover, fluorinated polymers are soluble in hydrofluoroether solvents, benign to biomolecules, and can be properly engineered to enable efficient photolithographic patterning. In this work, we report the development of a new photolithographic process for patterning biomolecules on any kind of surfaces either by physical adsorption or covalent bonding. The photoresist is based on a fluorinated material and hydrofluoroether solvents that have minimum interactions with biomolecules and thus they can be characterized as orthogonal to the biomolecules (bio-orthogonal). In both cases, the creation of patterns with dimensions down to 2 μm was achieved. The implementation of the developed photolithographic procedure for the creation of a multi-protein microarray is demonstrated.

A versatile, two-step, lift-off method, for the fabrication of flexible capacitive chemical sensors based on interdigitated electrodes (IDEs) is presented. A Polyimide (PI) foil whose one side is coated with a thin Aluminum (Al) film is used as the sensor substrate. The IDEs are then formed on the Al film using conventional semiconductor processes. Precise patterning of the sensor sensing layer, on the surface of the Al IDEs, is achieved using a two-step lift-off process which involves a first lift-off during which a Polyvinyl alcohol (PVA) film is spin-coated and patterned, followed by the deposition or spin coating of the sensing layer and a second lift-off to pattern it on the IDEs area and form the final sensor. The process allows for upscaling when a single sensing layer is deposited and patterned in batch over the whole wafer or for the easy fabrication of chemical sensor arrays when depositing and precisely patterning different sensing layers on an array of IDEs. Showcasing the first approach, PHITA copolymer (a methacrylate tertrapolymer) is deposited and patterned over sensors with varying electrode gaps in order to fabricate simple humidity sensors, while in a following experiment, Poly(2-hydroxyethyl methacrylate) (PHEMA), Epoxy novolac resin (EPN), Poly(methyl methacrylate) (PMMA) and Poly(hydroxy styrene) PHS are patterned on the IDEs in order to form a sensor array. The different sensor configurations realized are evaluated when exposed to water, methanol and ethanol vapors with PHS sensor exhibiting a capacitance change of 44 fF (sensitivity: 1.87 fF / %RH), 7.4 fF and 4.6 fF at 10,000 ppm respectively.

Over the past few years polymer nanocomposites have attracted considerable interest within the scientific community because they not only combine several alluring properties such as low weight, cost-efficiency and ease-of-formability, but mainly because they possess multi-faceted, multi-functional capabilities suitable for a wide range of applications, especially in the area of printed electronics. In this work, a two-step study was performed with the aim of developing ZnO/poly(methyl methacrylate) (PMMA) nanocomposites. The first step of the study encompassed the development of a facile, low-cost hydrothermal methodology to synthesize customized ZnO-nanostructures of controllable morphology and the detailed examination of the role of the materials used on the final shape and size of the produced nanostructures. The second step included studies to optimize the embedding of the produced nanostructures into PMMA matrices, mostly concentrating on the role of the solvent. The produced ZnO/PMMA nanocomposites were coated onto Si-based interdigitated electrode devices to explore their electrical characteristics and assess their potential to be employed for sensing applications.

Polymer nanocomposites have emerged as a new powerful class of materials because of their versatility, adaptability and wide applicability to a variety of fields. In this work, a facile and cost-effective method to develop poly(methyl methacrylate) (PMMA)-based polymer nanocomposites with copper oxide (CuO) nanofillers is presented. The study concentrates on finding an appropriate methodology to realize CuO/PMMA nanocomposites that could be used as resist materials for e-beam lithography (EBL) with the intention of being integrated into nanodevices. The CuO nanofillers were synthesized via a low-cost chemical synthesis, while several loadings, spin coating conditions and two solvents (acetone and methyl ethyl ketone) were explored and assessed with regards to their effect on producing CuO/PMMA nanocomposites. The nanocomposite films were patterned with EBL and contrast curve data and resolution analysis were used to evaluate their performance and suitability as a resist material. Micro-X-ray fluorescence spectroscopy (μ-XRF) complemented with XRF measurements via a handheld instrument (hh-XRF) was additionally employed as an alternative rapid and non-destructive technique in order to investigate the uniform dispersion of the nanofillers within the polymer matrix and to assist in the selection of the optimum preparation conditions. This study revealed that it is possible to produce low-cost CuO/PMMA nanocomposites as a novel resist material without resorting to complicated preparation techniques.

Anionic polymerization techniques along with functional initiation and/or functional termination reactions were employed for the synthesis of end-functionalized polymers composed from polystyrene (PS), polyisoprene-1,4 (PI), and polybutadiene-1,4 (PBd) chains bearing –OH end groups. Specifically, PS-OH, HO-PS-OH homopolymers, PS-b-PI-OH and PI-b-PS-OH block copolymers, HO-PS-b-PI-b-PS-OH triblock copolymers, and PS(PBd-OH)2 miktoarm star copolymers were prepared. The –OH functions were transformed into 2–ureido–4–pyrimidone, UPy, groups leading to the synthesis of the corresponding functionalized polymers. The UPy groups interact through the formation of strong hydrogen bonds. The aggregation behavior of selected samples was studied by a variety of techniques, such as size exclusion chromatography, dilute solution viscometry, dynamic light scattering, differential scanning calorimetry, thermogravimetric analysis, melt rheology, small angle X-ray scattering, and atomic force microscopy. It was found that in the solid state and in non-polar solvents, the UPy-terminated chains associate leading to the formation of dimers and larger aggregates. This systematic study presents a library of useful materials for potential applications and for fundamental studies linking associations, molecular structure, and macroscopic properties.

Two types of preformed alginate wet gels, one with a low (30-35%) and the other with a high (65-75%) content of glucuronic acid, were reacted with an aliphatic triisocyanate that was priorly allowed to diffuse in the pores. This reaction formed urethane groups on the surface of the alginate framework and also formed a polyurea (PUA) network connecting these urethane groups via respective reactions of the triisocyanate with alginate surface -OH groups or with gelation water remaining adsorbed on the inner surfaces of the wet gels. These processes formed a conformal nanothin film of PUA around the alginate network. After drying the wet gels with the supercritical fluid CO2, we obtained PUA/polyurethane-cross-linked alginate (X-alginate) aerogels. Although X-alginate aerogels are essentially copolymers, unlike all copolymers mentioned in previous literature reports, the relative topology of the alginate and the cross-linker is defined at the nanoscopic scale rather than at the molecular level. For the systematic study of X-alginate aerogels as a function of synthetic conditions, the experimental protocol was designed according to the central circumscribed rotatory design model using the alginate and the triisocyanate concentration as independent variables. Empirical models were derived for all relevant material properties by fitting experimental data to the two independent variables. The chemical identity of all samples was confirmed with attenuated total reflectance-Fourier transform infrared spectroscopy and solid-state C-13 and N-15 cross-polarization magic angle spinning NMR spectroscopy. The percentage of PUA uptake in X-alginate aerogels (58-98%) was calculated from skeletal density data. Scanning electron microscopy showed that all samples were nanofibrous, indicating that PUA coated conformally the skeletal network of both alginates, and the micromorphology remained the same as in the native (non-cross-linked) samples. X-alginate aerogels are mechanically strong materials, in contrast to their native counterparts, which are extremely weak mechanically. Compared to various organic aerogels from the literature, X-alginate aerogels can be as stiff as many other polymeric aerogels with 2 or 3 times higher densities. In addition, X-alginate aerogels are good candidates for sound insulation applications, as the speed of sound in most samples was estimated to be significantly lower than the speed of sound in dry air.

Cells in vivo are grown in a highly organized environment defined by the interactions with other cells and the extracellular matrix proteins. Thus, in order to shed light in cellular functions such as adhesion, migration, proliferation, apoptosis and differentiation, the creation of cell culture surfaces that mimic the in vivo environment has emerged. To create such surfaces, many microfabrication techniques have been applied so far. In this review, we focus on application of light-assisted patterning techniques for construction of either 2D or 3D cell culture substrates. In the first section of the review, the principle of the main light-assisted patterning approaches is presented and their advantages and limitations are discussed. In the second section, the influence of micro/nanopatterned surfaces fabricated with the described methods, on vital cell functions is presented, along with the significance of these findings in the field of tissue engineering and regenerative medicine.

A sensing system, based on tailor-made qPDMAEMA polymers, with the ability to discriminate between methanol and ethanol vapors in the presence or absence of humidity without the need of a separation column and at room temperature is designed and implemented. The miniaturized sensing system is comprised of four polymer coated planar capacitors along with the readout electronic module. The capacitors are fabricated with mainstream microelectronic/micromachining processes forming a planar InterDigitated Electrodes outline with 1 μm critical dimension. Tailor-made, hydrophilic homopolymers and a copolymer based on poly((2-dimethylamino)ethyl methacrylate), synthesized via GTP and quaternized with either methyl iodide or 1-(chloromethyl)naphthalene were used as the sensing layer and were compared to a hydrophobic, commercially available polymer. The sensing system was evaluated upon exposure to humidity, volatile organic compounds and binary mixtures of the latter. Data processing with Principal Component Analysis (PCA) highlights the ability of the proposed sensing system to discriminate between polar analytes, and more importantly between low molecular weight alcohol vapors, ethanol and methanol, in the presence of humidity.

The enrichment of cancer cell population when in mixtures with normal ones is of great importance for cancer diagnosis. In this work, poly(methyl methacrylate) films have been processed applying different oxygen plasma conditions to fabricate surfaces with structure height ranging from 22 to more than 2000 nm. The surfaces were then evaluated with respect to adhesion and proliferation of both normal and cancer human cells. In particular, normal skin and lung fibroblasts, and four different cancer cell lines, A431 (skin cancer), HT1080 (fibrosarcoma), A549 (lung cancer), and PC3 (prostate cancer), have been employed. It was found that adhesion and proliferation of cancer cells was favored when cultured onto the hierarchical micro/nanostructured surfaces as compared to untreated ones with the maximum values obtained for substrates treated at −100 V for 3 min. On the other hand, although the adhesion of normal fibroblasts was not influenced by the micro/nanostructured surfaces, their morphology and proliferation was significantly impaired, especially after 3-day culture on these surfaces. The reduced proliferation rate of adherent fibroblasts was linked to reduced focal points formation, as it was verified through vinculin staining, and not to apoptosis. The micro/nanostructured surfaces prepared with plasma treatment at −100 V for 3 min (hierarchical topography with mean height of ∼800 nm) were selected as substrates for normal and cancer cell co-culture experiments. It was found that 25–80 times enrichment of cancer over the normal cells was achieved on the nanostructured surfaces after 3-day culture, while it was 5–8 times lower on the untreated ones. It should be noticed that this is the first time such high enrichment ratios are achieved without implementing surfaces modified with binding molecules specific for cancer cells. Thus, the nanostructured surfaces hold a strong promise as culture substrates for separation and enrichment of cancer cells from mixtures with normal ones that should find application in cancer diagnostics.

One-dimensional polymeric photonic crystal (PC) arrays with tuned bandgap properties are designed and fabricated on the same substrate by employing mainstream micropatterning technologies and appropriate photopatternable materials. The two photopatternable materials are based on poly (2-hydroxy ethyl methacrylate) and epoxy polymers with the addition of appropriate photoacid generators and are diluted in orthogonal solvents, ethyl lactate and PGMEA respectively. The tuning of the photonic band gap of each photonic crystal is achieved through carefully tuned lithographic processing conditions with emphasis in low-lithographic contrast operation and gray scale lithography. By applying sequential lithographic steps in orthogonal developers one-dimensional photonic crystal arrays with 10 bi-layers are fabricated with very well defined patterns. With this approach, PC arrays with four distinct areas are realized on the same Si substrate with tuned reflectance spectrum covering the whole visible spectral regime.

In the present study, a one dimensional polymeric photonic crystal is designed, fabricated and evaluated as a humidity sensor. The polymeric photonic crystal is consisted of a multilayer stack of sequential hydrophobic and hydrophilic layers applied using conventional photolithographic steps: spin-coating and DUV exposure. During exposure in a humidity environment, the hydrophilic layers of the sensor swell, hence growing its optical path and giving a red-shift of the reflectance peak and consequently a different color of the device. The spectroscopic humidity sensor does not require external power since its sensing ability is based on the reflectance peak shift of the photonic crystal in the visible spectrum (color change of the sensor). The design, fabrication, evaluation and characterization of the device and its evaluation as humidity sensor is presented.

The ability to spatially deposit multiple biomolecules onto a single surface with high-resolution while retaining biomolecule stability and integrity is critical to the development of micro- and nanoscale bio-devices. While conventional lithographic patterning methods are attractive for this application, they typically require the use of UV exposure and/or harsh solvents and imaging materials, which may be damaging to fragile biomolecules. Here, we report the development of a new patterning process based on a fluorinated patterning material that is soluble in hydrofluoroether solvents, which we show to be benign to biomolecules, including proteins and DNA. We demonstrate the implementation of these materials into an orthogonal processing system for patterning multi-biomolecule arrays by imprint lithography at room temperature. We further showcase this method’s capacity for fabricating patterns of receptor-specific ligands for fundamental cell studies.

Commercially available permeable supports with microporous membranes have led to significant improvements in the culture of polarized cells because they permit them to feed basolaterally and thus carry out metabolism in a more in vivo-like setting. The porous nature of these membranes enables permeability measurements of drugs or biomolecules across the cellular barrier. However, current porous membranes have a high flow resistance due to great thickness (20-40 μm), low porosity, and a wide pore size distribution with tortuous diffusion paths, which make them low-throughput for permeability studies. Here we describe an alternate platform that is more flexible, allows for more control over physical parameters of the membranes, and is high-throughput. This study reports on the synthesis, nanofabrication, and surface characterization of a 3-μm-thick transparent membrane based on poly(4-hydroxy styrene) (PHOST). The membranes are nanofabricated using electron beam lithography and deep ion plasma etching to achieve an organized array of straight pores from 50 to 800 nm in diameter, with at least 23 times less flow resistance. It also shows for the first time the potential utility of PHOST as a cell culture substrate without cytotoxicity, and suitability for nanofabrication processes due to temperature stability.

One dimensional (1D) Photonic crystals (PC) are the simplest form of PC consisting of alternative layers of materials having different refractive indices. This periodic structure has very interesting optical properties allowing manipulation and control of light reflectance wavelength. Polymers have already been used as optical components in several devices and recently became candidate materials for the fabrication of PC. In the present work, a polymeric multilayer stack consisting of alternating hydrophobic and hydrophilic layers is fabricated and its response in controlled concentrations of humidity is evaluated towards the development of an optical humidity sensor.

2009 WILEY-VCH Verlag Gmb Organic electronics is an emerging technology opening new opportunities in the field of large-area electronics. It has received enormous attention as a technology platform that enables flexible, large-scale devices by exploiting the unique properties of organic materials. In addition, organic electronics offer the possibility of affordable manufacture of devices through solution processing of active materials. Before this vision is realized, several challenges must be overcome, in particular the issues of patterning. Patterning of electronic materials enables microscale device structures to be defined for organic light-emitting diode (OLED) displays and organic thin-film transistors (OTFTs). In addition, patterning enhances the device performance by preventing cross-talk, increases transconductance, and prevents high off-currents in transistor arrays or drivers. The patterning of organic materials has been demonstrated by many different methods, including ink-jet printing, vapor deposition through shadow masks, soft and hard imprint lithography, and photolithography. Ink-jet printing boasts continuous roll-to-roll process capabilities and is the patterning technique of choice for polymeric materials. However, the resolution is limited to approximately 10–20mm. Shadow mask deposition is the dominant technique for small-molecule patterning, but also has notable resolution limitations. A shadow mask feature resolution is typically 25–30mm, although special masks have shown resolution down to 5mm. Shadow-mask deposition also requires a high-vacuum environment, which can introduce further limitations. Imprint lithography has demonstrated promising results, showing feature resolution down to 10 nm. However, this technique has shown only limited applicability with respect to materials and device architectures. Furthermore, in all of the aforementioned methods, registration is an issue that renders fabrication of multilayer devices exceptionally challenging. Multilayered device architecture will be essential to achieve fully integrated circuits. Photolithography, in contrast, is a widely applicable patterning method that consistently achieves both high-resolution and registration. Photolithography has the added advantage of being the most developed patterning technology and the patterning method of choice for the current semiconductor industry. In spite of the proven technical advantages, conventional photolithography has not been recognized as a suitable technique for patterning organic electronic materials. It is presently hindered by concerns of chemical deterioration of active organic materials upon exposure to process solvents for lithography. By introducing a new set of benign processes that involve new specially tailored photopolymers, we show that this problem can be circumvented. Recently, we identified hydrofluoroethers (HFEs), a family of nontoxic and environmentally friendly solvents, as being chemically benign to nonfluorinated organic electronic materials. Not only are they benign, but HFEs are orthogonal solvents to many organic compounds, that is, the organic compounds are insoluble and are not swollen in HFEs. This is a particularly useful property in the fabrication of multilevel devices, since new layers can be added without damage to existing ones. Our challenge was, therefore, to develop compatible lithographic materials for these new process solvents. By employing a fluorinated photoresist compatible with HFEs, we demonstrate sub-micrometer photolithographic patterning of organic electronic materials. Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is a mechanically flexible, transparent, and highly conductive polymer blend, which has found various applications in organic electronics including serving as the electrode material for plastic substrates, because of its low-temperature processing requirements, and as charge-injection/-extraction layers in OLEDs and photovoltaic devices. However, photolithographic patterning of PEDOT:PSS for device components is not straightforward, because i) PEDOT:PSS films are damaged by aqueous solutions, which are standard developers in conventional photolithography, and ii) acid-sensitive photoresists are adversely affected by the acidic PEDOT:PSS. In this communication,wepresent a unique acid-stable imaging material for PEDOT:PSS and organic electronic materials in general. We report on the sub-micrometer patterning of PEDOT:PSS films and their subsequent application to the fabrication of a field-effect transistor, in which an organic semiconductor material, pentacene, is patterned by the same protocol. In designing a HFE-compatible photoresist, it was most important that the photoresist be soluble in fluorous solvents. In general, fluorous solvents dissolve highly fluorinated materials. The copolymer 3, derived from the highly fluorinated monomer 1 and photolabile monomer 2, was expected to yield a material that exhibits a solubility switch following UV irradiation

The exchange bias field (H"E) and coercive field (H"c) of ferromagnetic (FM)-antiferromagnetic (AM) nanostructures have been investigated by SQUID magnetic measurements. The fabricated structures were small cylinders of 700nm diameter and consisted of NiFe/IrMn sandwiches. In the present work, the exchange bias has been investigated as a function of ferromagnetic layer thickness t"F"M. In addition, an enhancement of coercivity is observed.

The magnetotransport properties of [Co(1nm)/Bi(2.5nm)]"1"0 multilayers are examined in line structures prepared by magnetron sputtering and a two-step microfabrication process. At 10K the transverse magnetoresistance (MR) in [Co(1nm)/Bi(2.5nm)]"1"0 line structures exhibits a @DR/R=80% effect, and a change of the anomalous Hall effect (AHE) voltage equal to 21% in thin films. At 300K this MR effect becomes 27% whereas the AHE contribution changes the polarity of the spontaneous Hall resistance loop from negative at 10K to positive in the MR loop. Such large MR effect may find applications in magnetoelectronic devices.

The formation of micro/nanostructures that can be used for binding of specific biomolecules is of great importance for the development of multi-analyte biosensing devices and high-throughput microarrays. In this paper, we report on the chemical binding of biotin on an epoxy photolithographically patterned surface. In particular, we used a negative chemically amplified epoxy resist (EPR) in order to create very small structures by photolithography, in which biotin derivatives functionalized with succinimidyl ester or an amine group were immobilized through covalent bonding. Lithographic process with exposure at 248nm was optimized, and structures with diameter down to [email protected] were demonstrated, where biomolecules were successfully bound.

Organic electronics is an extensively studied subject opening new horizons in electronics technology. It has attracted great attention as a technology to enable flexible electronic devices through solution processing of organic and polymeric materials. However, patterning of organic materials to construct device components still remains one of the major hurdles to be overcome due to problems with chemical processing. Fundamentally this challenge originates from the limited number of options regarding orthogonal solvents. Recently, we have identified supercritical carbon dioxide (scCO2) and segregated hydrofluoroethers (HFEs) as universal, non-damaging solvents for most non-fluorinated polymeric materials. These unconventional solvents expand processing options from the two-dimensional plane to three-dimensional space by drawing another orthogonal axis. Taking advantage of those noble solvents and fluorinated photoresists, we were able to make patterns of functional organic materials photolithographically. Furthermore, our orthogonal processing method has been applied to the fabrication of a patterned polymer light-emitting device in scCO2 and an organic thin-film transisotor in HFEs.

In this paper, proton beam writing is combined with an aqueous developable-easily stripped negative chemically amplified resist (TADEP: thick aqueous developable epoxy resist) for the realization of high aspect ratio structures. Monte Carlo method is used to simulate PBW in thick resist films. Result shows that resist structures with 280 nm linewidth and aspect ratio of 40 were easily resolved.

A study was conducted to demonstrate a new approach for chemicalprocessing of organic electronic materials. It was demonstrated that the approach is based on the use of fluorous solvents, segregated hydrofluoroethers (HFE). The study also demonstrated that that processing organic electronics, using HFEs under extreme conditions, such as boiling temperatures, does not cause any dissolution, cracking, delamination,or other unfavorable physical or chemical change. The study also demonstrated that the use of fluorous solvents enables simple photolithographic patterning of organic electronic materials. It was shown that fluorous solvents are perfluorinated on very highly fluorinated liquids, which are immiscible with organic solvents and water.

Proton beam writing (PBW) is a new direct-writing process that uses a focused beam of MeV protons to pattern resist material at nano dimensions. PBW has the unique ability to maintain a straight path through 50µm thick resist films, and is suitable for high aspect ratio micro(nano)-machining. TADEP resist is a new promising high aspect ratio chemically-amplified resist that can be developed in aqueous base developer and has the capability of stripping in conventional stripping schemes. By employing PBW on TADEP resist patterns with 280nm linewidth and a thickness of 12µm have been resolved showing an aspect ratio of 42. Following Ni electroplating of the TADEP features, Ni structures of height 0.8µm and spacing of 167nm, produced in 2µm thick TADEP, were demonstrated indicating the easy stripping characteristics of the TADEP resist.

The dependence of magnetoresistance (MR) on the magnetization reversal processes was studied in Co and NiFe line structures with pads. Conventional patterning and deposition processes are applied for the fabrication of a device that consists of five-line structures with a line-width of 2µm. It is demonstrated that the large asymmetry of AMR loops in Co-lines, which are observed after a field-cooling process, might pave the way for applications in magnetoelectronic devices where the magnetic field direction parallel or antiparallel to dc-current direction inside the magnetic line structures really matters.

We have fabricated a periodic array of holes with diameters of a few microns on thin metal films on a Si substrate by using lithographic techniques, and demonstrate that the structures show extraordinary transmission in the infrared spectrum. Our structures become efficient narrow-band infrared thermal emitters when the hole pattern is transferred to the Si substrate by dry etching using the metal as a mask. The influence of the geometrical parameters, like the hole depth and diameter, on the emission spectra was considered in order to optimize the optical properties.

A variety of different photo resists are used for the fabrication of polymer and metal high aspect ratio structures. Among them SU-8, a chemically amplified negative tone photoresist is the mostly used. However, after processing the finished resist pattern (SU-8) is hardly removed from the substrate. In the present work the formulation and process optimization of a negative tone chemically amplified photoresist (TADEP) is presented. TADEP resist owns two advantages: the dissolution of the uncrosslinked areas in IC standard aqueous developers and the easy stripping in acetone by the assistance of ultrasonic bath. The TADEP resist is successfully applied for the fabrication of polymer and metal structures, after electroplating and stripping and also in the case of Proton Beam Writing.

Evangelia Sarantopoulou, Zoe Kollia*, Margarita Chatzichristidi**, Antonios Douvas**, Panagiotis Argitis**, Spomenka Kobe*** , Alkiviadis-Constantinos Cefalas*. National Hellenic Research Foundation, TPCI,48 Vas. Constantinou Aven. Athens 11635 Greece email: ccefalas@eie.gr Institute of Microelectronics, NCSR Demokritos, 15310 Agia Paraskevi, Greece Jožef Stefan Institute,Department of Nanostructured Materials, Jamova 39, SI-1000 Ljubljana, Slovenia

In this paper the design considerations, fabrication and first evaluation results of a capacitive type single chip chemical sensor array based on interdigitated electrode structure is presented. The electrode arrays have been fabricated with conventional semiconductor processes. The final structure consists of four interdigital capacitive sensors each one coated with a different polymer sensitive film by using only successive lithographic steps. The array sensors have good response to controlled concentrations of volatile organic compounds (∼35fF, ∼7fF, ∼12fF for the PHEMA covered sensor when exposed to 100 ppm of water, methanol and ethanol vapors and ∼2.5fF, in the case of 100 ppm of toluene vapors for the PDMS covered sensor).

Surface modification of polymeric films by VUV light is an efficient method to tailor its prop- erties and functionality for a variety of applications. Laser irradiation at 157 nm of poly(methyl methacrylate) (PMMA) thin films deposited on SiO2 layer, demonstrates a considerable increase of surface and bulk swelling during water vapour sorption in comparison to the non irradiated film ar- eas. AFM images of surface morphology of the irradiated areas reveal that surface roughness de- pends on the irradiation conditions. Besides morphological changes, X-ray photoelectron spectros- copy (XPS) suggests chemical modification of the irradiated film areas. The enhanced surface swelling and the chemical modification increases the detection efficiency of water analyte in gas phase by many orders of magnitude. This method can be used to fabricate a polymer based sensor array and to engineer its detection efficiency.

Specification of laser ablating parameters is important to fabricate biomolecule microarrays with enhanced sensitivity and speed. Optimum fabricated conditions occur when thin surface layers of biocompatible fluoropolymers, (poly(2,2,2-trifluoroethyl methacrylate),, were ablated with nano-scale spatial resolution using laser at 157 nm. The surface ablation efficiency, morphology, molecular dissociation within the polymer volume and other effects, such as the formation of nano-columns depend on the exposing conditions and the laser beam spot size. The efficiency of surface ablation for PTFEMA and Teflon AF was greatly reduced for laser beam dimensions below 10 and 50 μm respectively and for large beam spot sizes, > 50 μm, the ablative rate was 0.5 and 0.8 nm at 1 mJ/cm2 laser fluence respectively.

Surface relief gratings (SRG) and self-organized nano-structures induced by laser light at 157 nm on the fluoropolymer poly(2,2,2trifluoroethyl methacrylate) (PTFEMA), films were obtained under well-controlled light exposure conditions. Regular and semi-regular spaced self-organized grating-like structures were created on polymeric films for � 7.5‐100 mJ/cm 2 laser energy fluence. For lower laser fluence, the surface morphology of light exposed/non-exposed areas exhibited irregular-like structure morphologies, while polymer surface irradiation with energyfluencehigherthan150 mJ/cm 2 causesprogressivelyfadingoutof theregularpatterns.Underthespecificexperimentalconditions, theSRG and self-organization patterning have their origin in the development of a surface thermal instability (Rayleigh’s instability), which is resolved itself into regular patterns on the surface of the fluoropolymer film. The thermal instability is due to the explosive polymer surface photodissociation at 157 nm and the build up of longitudinal and periodic surface stress, which eventually create the SRG and the self-assembled structures on the polymer. # 2007 Elsevier B.V. All rights reserved.

The exchange bias field (H"E) and coercive field (H"c) of Ferromagnetic (FM)-Antiferromagnetic (AM) nanostructures have been investigated by SQUID magnetic measurements. The fabricated structures were small cylinders of 700nm diameter and consisted of NiFe/IrMn sandwiches. In the present work, the exchange bias has been investigated as a function of antiferromagnetic layer thickness t"A"F. In addition, an enchancement of coercivity is observed.

Metal-insulator-like (MI) behavior in semi-metallic Bi-nanowires and single crystals indicate that semimetals exhibit a combination of unusual features of metal-insulating behavior which are accompanied by anomalously high magnetoresistance. These effects make semi-metallic Bi a potential candidate for use in magneto-electronic devices. The present study examines the magneto-transport properties of Bi-line structures, focusing on magnetic field driven MI transitions. Conventional patterning and deposition processes are applied for the fabrication of a device that consists of five Bi-lines with line-widths of [email protected]

A novel layer-by-layer fabrication approach for the manufacturing of long embedded microchannels is presented. The methodology is based on the use of two epoxy based photoresist layers with different photo acid generator (PAG) concentration. Using this methodology long, functional microchannels are demonstrated. The technology has been optimized through tuning of the epoxy molecular weight, PAG concentrations and processing conditions. Finally, a basic microfluidic application is presented. (c) 2006 Elsevier B.V. All rights reserved. Microelectronic Engineering

Nowadays a significant amount of research effort is devoted to the development of technologies for the fabrication of microcomponents and microsystems worldwide. In certain applications of micromachining high aspect ratio (HAR) structures are required. However, the resist materials used in HAR technologies are usually not compatible with the IC fabrication, either because they cannot be stripped away or because they are developed in organic solvents. In the present work the application of a novel chemically amplified resist for proton beam micromachining is presented. The resist based on epoxy and polyhydroxystyrene polymers is developed in the IC standard aqueous developers. The exposed areas can be stripped away using conventional organic stripping solutions. In order to test the exposure dose sensitivity and the lateral resolution, various test structures were irradiated. Using this formulation 5–8 μm wide lines with aspect ratio 4–6 were resolved.

The patterning of high aspect ratio structures in ultra thick photoresist films is extremely challenging. Photoresists used should provide low absorption in order to achieve vertical sidewalls and easy stripping after the pattern transfer process. In the current work, a novel resist platform is presented and applied for lithographic evaluation in film thickness up to 60 μm. The resist formulation consists of a mixture of an epoxy novolac oligomer, partially hydrogenated poly(4-hydroxystyrene) and onium salt photoacid generators. Since the resist is rich in hydroxyl groups the unexposed regions can be developed in standard aqueous base solutions (TMAH, 0.26 N). Additionally since the required crosslink density for solubility change is limited, the crosslinked regions can be easily removed by commercial wet photoresist strippers. First experimental data revealed promising lithographic performance with resolution down to 20 μm with an aspect ratio 3:1.

A novel approach for photochemical definition of distinct, basic color, emission areas in thin polymeric films is introduced. Two-color, blue and green, fluorescence imaging is demonstrated using an amino diphenylhexatriene derivative that upon protonation shows sizable shifts in both absorbance and fluorescence spectra. Protons are generated photochemically in selected areas of the thin polymeric films containing the probe by a typical onium salt photoacid generator. Significant “flow” of transferred electronic energy from a typical aromatic polymer, epoxy novolac, to the mentioned dye was manifested permitting amplification and color tunability of fluorescent signals.

An increasing number of nowadays advanced lithographic technologies require photoresist film thickness of at least 50μm. The patterning of high aspect ratio structures in ultra thick photoresist films is extremely challenging and the photoresists should provide low absorption in order to achieve vertical sidewalls and easy stripping after the pattern transfer processing. In the current work a novel resist platform is presented and applied in the case of film thicknesses up to 65μm. The resist formulation consists of a mixture of an epoxy novolac oligomer and poly(hydroxy styrene) and onium salt photoacid generators. Since the resist is rich in hydroxyl groups the unexposed regions can be developed in industrial aqueous solutions (TMAH 0.27N). Additionally since the required crosslink density is limited, the crosslinked regions can be easily removed by commercial wet photoresist strippers. First experimental data reveal a promising lithographic performance with resolution down to 30μm.

The fabrication of a power-free, reversible, color-indicator sensor of the relative humidity in the environment has numerous applications and is considered a challenging task. The device to be developed should be able of color changing according to the degree of humidity change and have a number of characteristics, i.e., reversibility, fast response, low cost, and, ideally, should be flexible. The proposed solution, based on a 1-D polymeric Photonic Crystal (PC) configuration on a microscope glass, can successfully fulfill all the above requirements.