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The science and engineering of two-dimensional materials (2DMs), in particular, of 2D semiconductors, is advancing at a thriving pace. It is well known that these delicate few-atoms thick materials can be damaged during the processing toward their integration into final devices. Thermal scanning probe lithography (t-SPL) is a gentle alternative to the typically used electron beam lithography to fabricate these devices avoiding the use of electrons, which are well known to deteriorate the 2DMs' properties. Here, t-SPL is used for the fabrication of MoS2-based field effect transistors (FETs). In particular, the use of t-SPL is demonstrated for the first time for the fabrication of edge-contact MoS2 FETs, combining the hot-tip patterning and Ar+ milling to etch the 2DM. To avoid contamination of the contact interface by atmospheric gas molecules, etching and metal deposition are performed without breaking the vacuum conditions in between. With this process, edge-contact MoS2 FETs are successfully fabricated and characterized. On/off ratios up to 108 and 109 are obtained at room temperature in air and vacuum, respectively, i.e., comparable with the best values reported in the literature., The authors thank the Center of Micro/Nanotechnology (CMi) of EPFL. We also thank Sadegh Kamaei, Teodor Rosca, and Prof. A. M. Ionescu for their help with the electrical measurement set-up and access to their instruments. This work received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovation Program (Project “MEMS 4.0”, ERC-2016-ADG, grant agreement no. 742685)., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

Embedding liquid metals (LMs) into an elastomer is emerging as a promising strategy for stretchable conductors. Existing manufacturing techniques are struggling between spatial resolution and process complexity and are limited to chemically resistant substrates. Here, we report on a hybrid process combining stencil lithography and centrifugal force-assisted patterning of liquid metal for the development of LM-based stretchable conductors. The selective wetting behavior of oxide-removed eutectic gallium–indium (EGaIn) on metal patterns defined by stencil lithography enables micrometer scale LM patterns on an elastomeric substrate. Stencil lithography allows for defining metal regions without harsh chemical treatments, making it suitable for a wide range of substrates. Microscale LM patterns are achieved by efficiently removing the excess material by the centrifugal forces experienced from spinning the substrate. The proposed approach allows for the creation of LM patterns with a line width as small as 2 μm on a stretchable poly(dimethylsiloxane) (PDMS) substrate. The electrical measurement results show that the fabricated EGaIn devices can endure 40% mechanical strain over several thousands of cycles. Furthermore, a stencil design using microbridges is proposed to address the mechanical stability issue in stencil lithography. An EGaIn conductor with a serpentine structure and an interdigitated capacitor are fabricated and characterized. The results demonstrate that the patterned serpentine conductors retain their functionality with applied mechanical strain up to 80%. The performance of the interdigitated capacitors upon applied strain is in good agreement with the theoretical estimation. Finally, we demonstrate our approach also on poly(octamethylene maleate (anhydride) citrate) (POMaC) substrates to broaden the use of the proposed method to not only flexible and stretchable but also biodegradable substrates, opening a way for in vivo transient microsystem engineering. The work presented here provides a versatile and reliable approach for manufacturing stretchable conductors.

The science and engineering of two-dimensional materials (2DMs), in particular, of 2D semiconductors, is advancing at a thriving pace. It is well known that these delicate few-atoms thick materials can be damaged during the processing toward their integration into final devices. Thermal scanning probe lithography (t-SPL) is a gentle alternative to the typically used electron beam lithography to fabricate these devices avoiding the use of electrons, which are well known to deteriorate the 2DMs' properties. Here, t-SPL is used for the fabrication of MoS

Melt electrowriting (MEW) is a distinct class of additive manufacturing technologies that generates fibrous and porous macrostructures with microscale resolution from an electrically charged molten polymer. The high -resolution scaffolds produced by MEW have been primarily used for tissue engineering, cancer research, bio-fabrication and biomaterials. Unfortunately, the commercial MEW device's prohibitive affordability and lack of standardization of custom devices, represent obstacles to further research. Built on the achievements and affordability of material extrusion 3D printers, we convert an open-source Voron 0.1 printer into a highly capable MEW device, termed as MEWron. To guarantee availability, the use of commercial and affordable components is prioritized, while in the cases where this has not been possible, 3D printed, and easy-to-machine components have been employed. Two main approaches have been followed, the first one focused on the existing material extrusion configuration (i.e., filament-based feeding system and material input) while the second one focuses on a conventional MEW pneumatic feeding system and syringe reservoir. When not including the high voltage supply, both approaches have a final budget below $1000. The manuscript describes all required steps and components to modify a Voron 0.1 printer and provides the computer-aided design (CAD) for required custom components reproduction. Moreover, the MEWron devices' reliability is demonstrated, as well as their potential to extend the MEW field boundaries. We believe that the open-source MEWron device will facilitate unprece-dented MEW technology accessibility using a well-established and modifiable platform.

Objective Colloid solutions are commonly used to maintain perioperative fluid homeostasis. In regard to perioperative infant-centered care, data about the impact of colloids are rare. New data suggest a possible positive effect of hydroxyethyl starch (HES) concerning blood brain barrier. Therefore we conduct a retrospective single center study of children scheduled for neurosurgery, age 10% of body blood volume, receiving either 6% HES 130/0.4 or 5% human albumin (HA). Results Out of 913 patients, 86 were included (HES = 30; HA = 56). Compared to HES [16.4 ± 9.2 ml/kg body weight (mean ± SD)] HA group received more colloid volume (25.7 ± 11.3), which had more blood loss [HA 54.8 ± 45.0; HES 30.5 ± 30.0 (%) estimated blood volume] and higher fluid balances. Fibrinogen was decreased and activated partial thromboplastin time was elevated in HA group. Urinary output, creatinine and urea levels did not differ between the two groups. Serum calcium, total protein levels were lower in HES group. HA treated infants tended to have shorter ICU and hospital stays. We conclude that none of the investigated colloid solutions were without leverage to infants. Consequently randomized controlled trials about perioperative goal-directed fluid replacement of children undergoing (neuro)-surgery with major blood loss are needed.

Local bandgap tuning in two-dimensional (2D) materials is of significant importance for electronic and optoelectronic devices but achieving controllable and reproducible strain engineering at the nanoscale remains a challenge. Here, we report on thermomechanical nanoindentation with a scanning probe to create strain nanopatterns in 2D transition metal dichalcogenides and graphene, enabling arbitrary patterns with a modulated bandgap at a spatial resolution down to 20 nm. The 2D material is in contact via van der Waals interactions with a thin polymer layer underneath that deforms due to the heat and indentation force from the heated probe. Specifically, we demonstrate that the local bandgap of molybdenum disulfide (MoS2) is spatially modulated up to 10% and is tunable up to 180 meV in magnitude at a linear rate of about −70 meV per percent of strain. The technique provides a versatile tool for investigating the localized strain engineering of 2D materials with nanometer-scale resolution., Nano Letters, 20 (11), ISSN:1530-6984, ISSN:1530-6992

The growth of MoS2 layers of desired dimensions at predefined locations is essential for fabricating opto-electronic devices based solely on MoS2 or on hetero-structures based on MoS2. Here we present a new route for patterned growth of MoS2 by combining radio frequency (RF) magnetron sputtering, stencil mask lithography and vapour phase sulfurization. The present method does not involve chemical etchants and organic photoresist and hence provides a simplified process of achieving MoS2 patterns. Here, the control over the number of layers (mono, few and bulk) of MoS2 is achieved by varying the thickness of Mo films. The statistical variation in thickness i.e., number of MoS2 layers within the individual patterns is investigated from Raman mappings which revealed the uniform growth of 3-4 MoS2 layers. From Kelvin probe force microscopy, the surface potential values of MoS2 patterns lie in the range -350 to -370 mV, which is consistent with 2D MoS2 layer with thickness of 3-4 layers. The surface potential analysis across individual patterns indicates weakly n-type doping of few layers MoS2 with Fermi level located ~0.83-0.85 eV below the conduction band edge.

We report on the design and characterization of single-chip electron spin resonance (ESR) detectors operating at 50 GHz, 92 GHz, and 146 GHz. The core of the single-chip ESR detectors is an integrated LC-oscillator, formed by a single turn aluminum planar coil, a metal-oxide-metal capacitor, and two metal-oxide semiconductor field effect transistors used as negative resistance network. On the same chip, a second, nominally identical, LC-oscillator together with a mixer and an output buffer are also integrated. Thanks to the slightly asymmetric capacitance of the mixer inputs, a signal at a few hundreds of MHz is obtained at the output of the mixer. The mixer is used for frequency down-conversion, with the aim to obtain an output signal at a frequency easily manageable off-chip. The coil diameters are 120 μm, 70 μm, and 45 μm for the U-band, W-band, and the D-band oscillators, respectively. The experimental frequency noises at 100 kHz offset from the carrier are 90 Hz/Hz1/2, 300 Hz/Hz1/2, and 700 Hz/Hz1/2 at 300 K, respectively. The ESR spectra are obtained by measuring the frequency variations of the single-chip oscillators as a function of the applied magnetic field. The experimental spin sensitivities, as measured with a sample of α,γ-bisdiphenylene-β-phenylallyl (BDPA)/benzene complex, are 1 × 108 spins/Hz1/2, 4 × 107 spins/Hz1/2, 2 × 107 spins/Hz1/2 at 300 K, respectively. We also show the possibility to perform experiments up to 360 GHz by means of the higher harmonics in the microwave field produced by the integrated single-chip LC-oscillators.

Triboelectric nanogenerator (TENG) has proven to be a robust power source to efficiently convert ambient mechanical energy into electricity. It experienced substantial growth in the past years owing to its appealing features that make it superior than other self-powering principles. In particular, it excels in high output performance, sustainability in powering capability, as well as the ability to work completely autonomously. However, in order for TENG to make a real impact for societal applications, further improvements towards cost-effective TENG are required, in particular by exploring new inexpensive electrification materials and by simplifying the manufacture procedure. In this work, we present a paper-TENG completely prepared using cost efficient, commercially available commodity materials, such as paper cards, Teflon tape, and graphite pencil. Here, paper was firstly utilized as both supporting structure and functionally triboelectric pair simultaneously, which is widely available at low cost, and in addition, to our advantage, it has a considerably high ability to lose electrons during triboelectrification. As scalable fabrication, we implemented a single step using sandpaper imprinting to increase effective friction area and simple electrode fabrication by means of a graphite pencil. These two technical innovations were systematically studied as to the micro/nano-textured surfaces and conductive electrodes. The electrical properties of fabricated paper TENGs were comprehensively investigated and proved to be a usable power source by using a well-designed vibration platform and practical body motion, respectively. The fabricated paper TENG was successfully utilized to move liquid droplets in designated directions via electro-wetting. This new implementation of controlled droplet manipulation shows an attractive potential of TENG's applications in multidisciplinary fields, such as inkjet printing and lab-on-chip biomedical micro/nano-systems.

The spatiotemporal architecture of the cell membrane and diffusion dynamics of its constituents (lipids and proteins) are critical for many cellular processes such as signaling, trafficking and cell adhesions. Sub-diffraction photonics based on plasmonics offer new opportunities to follow such events as they can confine electric fields in nanoscale hotspots with spatial dimensions comparable to single molecules (∼5 nm).

The challenging fabrication of sub-100-nm structures with high aspect ratio by UV-nanoimprint lithography (NIL) is addressed in this work. Thermal shrinkage is induced by cooling the structures below room temperature to avoid the issues commonly arising during the release of the polymeric nanostructures from the master. The UV-NIL has been performed to obtain OrmoComp(A (R)) nanostructures using OrmoStamp(A (R)) working stamps copied from Si masters. Nanoridges and nanopillars with 45 nm width and 380 nm thickness have been fabricated with a corresponding aspect ratio of 8.5. This is, to the best of our knowledge, the highest aspect ratio achieved using organic-inorganic hybrid materials at the sub-100-nm scale.

A strategy for a simple dispersion of commercial multi-walled carbon nanotubes (MWCNTs) using two organosilicones, polycarbosilane SMP10 and polysilazane Ceraset PSZ20, in organic solvents such as cyclohexane, tetrahydrofuran (THF), m-xylene and chloroform is presented. In just a few minutes the combined action of sonication and the presence of Pt(0) catalyst is sufficient to obtain a homogeneous suspension, thanks to the rapid hydrosilylation reaction between SiH groups of the polymer and the CNT sidewall. The as-produced suspensions have a particle size distribution

In recent years, a new electrification-based mechanism called triboelectric generator (TEG) has been demonstrated as a stable and renewable power source to convert ambient energy into remarkable electrical output. Various TEG configurations have been proposed to enhance the output performance focusing on improvements to its working principle and structural geometry. In order for TEG to make an impact in real life applications, further improvement is needed in particular in the choice of the pair of electrification materials beyond the choice of traditional materials that have been employed in the construction of TEGs. Here, we investigate silk fibroin as a novel material for TEG that occupies a top-tier position in the triboelectric series and possesses the outstanding ability of losing electrons easily. Several technical challenges have been successfully addressed and are shown herein. For instance, an oxygen plasma process is employed to improve the interfacial energy between silk fibroin film and substrate by chemical modification and nanoscale roughness increase, which allows for the reliable switching mechanism needed to generate the electric power. The comprehensive study and the systematical measurement were carried out to study the fabricated TEG, including electrical output test, stability and reliability, humidity effect, and performance comparison with traditional materials. The silk fibroin is proven to be a promising material to construct TEG, and the fabricated TEG exhibits stable high-output performance, with maximum voltage, current, and power density of 268 V, 5.78 μA, and 193.6 μW/cm2, respectively, to a load of 40 MΩ. Furthermore, this silk fibroin film has two advantageous potentials for the development of TEGs: higher than 90% transmittance in the visible spectrum region and controllable solubility in aqueous solutions. The former property preserves the intrinsic optical property of TEG and enables the realisation of an ultra-transparent device, while the latter moves us closer to the attractive future vision of realising TEG systems that biodegradable for environmental sensing or implantable for biomedical applications. Additionally, we demonstrate that his silk-fibroin-based TEG can directly produce energy to power two 4-bit liquid crystal displays (LCDs) and to actuate a microscale cantilever. As the first demonstration of TEG applied to power a mechanical micro-device,thisTEG-micro-cantilever microsystem shows an attractive potential to realize fully integrated smart transducers that are needed for autonomous sensor networks.

This letter reports on a novel fabrication method for 3D metal nanostructures using high-throughput nanostencil lithography. Aperture clogging, which occurs on the stencil membranes during physical vapor deposition, is leveraged to create complex topographies on the nanoscale. The precision of the 3D nanofabrication method is studied in terms of geometric parameters and material types. The versatility of the technique is demonstrated by various symmetric and chiral patterns made of Al and Au.

International audience; The electro-mechanical sensing properties of freestanding monolayered membranes of dodecanethiol coated 7 nm gold nanoparticles (NPs) are investigated using AFM force spectroscopy and conductive AFM simultaneously. The electrical resistance of the NP membranes increases sensitively with the point-load force applied in the center of the membranes using an AFM tip. Numerical simulations of electronic conduction in a hexagonally close-packed two-dimensional (2D) array of NPs under point load-deformation are carried out on the basis of electronic transport measurements at low temperatures and strain modeling of the NP membranes by finite element analysis. These simulations, supporting AFM-based electro-mechanical measurements, attribute the high strain sensitivity of the monolayered NP membranes to the exponential dependence of the tunnel electron transport in 2D NP arrays on the strain-induced length variation of the interparticle junctions. This work thus evidences a new class of highly sensitive nano-electro-mechanical systems based on freestanding monolayered gold NP membranes.

Nuclear magnetic resonance (NMR) experiments on subnanoliter (sub-nL) volumes are hindered by the limited sensitivity of the detector and the difficulties in positioning and holding such small samples in proximity of the detector. In this work, we report on NMR experiments on liquid and biological entities immersed in liquids having volumes down to 100 pL. These measurements are enabled by the fabrication of high spatial resolution 3D printed microfluidic structures, specifically conceived to guide and confine sub-nL samples in the sub-nL most sensitive volume of a single-chip integrated NMR probe. The microfluidic structures are fabricated using a two-photon polymerization 3D printing technique having a resolution better than 1 μm3. The high spatial resolution 3D printing approach adopted here allows to rapidly fabricate complex microfluidic structures tailored to position, hold, and feed biological samples, with a design that maximizes the NMR signals amplitude and minimizes the static magnetic field inhomogeneities. The layer separating the sample from the microcoil, crucial to exploit the volume of maximum sensitivity of the detector, has a thickness of 10 μm. To demonstrate the potential of this approach, we report NMR experiments on sub-nL intact biological entities in liquid media, specifically ova of the tardigrade Richtersius coronifer and sections of Caenorhabditis elegans nematodes. We show a sensitivity of 2.5x1013 spins/Hz1/2 on 1H nuclei at 7 T, sufficient to detect 6 pmol of 1H nuclei of endogenous compounds in active volumes down to 100 pL and in a measurement time of 3 hours. Spectral resolutions of 0.01 ppm in liquid samples and of 0.1 ppm in the investigated biological entities are also demonstrated. The obtained results may indicate a route for NMR studies at the single unit level of important biological entities having sub-nL volumes, such as living microscopic organisms and eggs of several mammalians, humans included.

© 2015 Elsevier Ltd. The effect of MWCNT introduction in a polycarbosilane based ceramic on its electrical properties is presented. The electrical conductivity of two MWCNT powders was measured under dynamic compaction up to 20MPa when it reached 3 5S/cm. The compaction behavior was also analyzed and modeled. A composite was then realized using allylhydridopolycarbosilane SMP10® and divinylbenzene as matrix. Intact 10mm MWCNT SiC ceramic discs samples with 2wt. filler load were produced pressure less via liquid route despite the linear shrinkage of about 30. Nanotubes microstructure and distribution in the matrix were confirmed after pyrolysis with TEM and SEM analysis. Anyhow similar electrical conductivity values after pyrolysis between the loaded and unloaded samples were measured. The microstructure analysis via XRD and TEM revealed that the percolative carbon network formed through the use of divinylbenzene improves the electric conductivity more than that of MWCNT addition and also simplifies the whole process.

We present a novel blurring-free stencil lithography patterning technique for high-throughput fabrication of large-scale arrays of nanoaperture optical antennas. The approach relies on dry etching through nanostencils to achieve reproducible and uniform control of nanoantenna geometries at the nanoscale, over millimeter-sizes in a thin aluminum film. We demonstrate the fabrication of over 400 000 bowtie nanoaperture (BNA) antennas on biocompatible substrates, having gap sizes ranging from (80 ± 5) nm down to (20 ± 10) nm. To validate their applicability on live cell research, we used the antenna substrates as hotspots of localized illumination to excite fluorescently labeled lipids on living cell membranes. The high signal-to-background afforded by the BNA arrays allowed the recording of single fluorescent bursts corresponding to the passage of freely diffusing individual lipids through hotspot excitation regions as small as 20 nm. Statistical analysis of burst length and intensity together with simulations demonstrate that the measured signals arise from the ultraconfined excitation region of the antennas. Because these inexpensive antenna arrays are fully biocompatible and amenable to their integration in most fluorescence microscopes, we foresee a large number of applications including the investigation of the plasma membrane of living cells with nanoscale resolution at endogenous expression levels.

In this paper a nanofluidic molecular filtration system based on soft alginate hydrogel fillings and a solid-state alumina support membrane is presented. The electrostatically controlled diffusion is characterized by partition coefficient of the hydrogel and the flux through the composite membrane for positively and negatively charged dye molecules. The partition coefficient of negatively charged fluorescein sodium molecules into the gel is 2 orders of magnitude lower in 1 mM KCl solution than that in 1 M KCl solution. The molecular transport properties through the hydrogel loaded alumina membrane are solely dominated by the soft nanoporous hydrogel. Such a composite membrane with alginate hydrogel of only 6 wt% shows a selectivity of 5 for the separation of bovine serum albumin (BSA) and bovine hemoglobin (BHb) in high ionic strength solution of phosphate-buffered saline (PBS). (C) 2014 Elsevier B.V. All rights reserved.

We present a review on stencil lithography and focus on the particular interest and challenges when applying it to the scalable fabrication of nm-size devices. We first describe the basic technique with its main advantages and challenges. Then we review the key results of stencil lithography in nanoscale patterning for the direct deposition of complex materials and the patterning on non-conventional substrates. In particular we discuss the blurring, which is a major limitation to achieving high pattern resolution in stencil lithography. Successful strategies to reduce the blurring based on etching processes and novel stencil designs are presented. Moreover, the paper presents the use of stencil masks beyond deposition, namely for localized etching and ion implantation processes. We also review the current state in research of dynamic stencil lithography, which is based on displacing the stencils with respect to the substrate during deposition. The paper concludes by presenting a broad range of applications for stencil lithography that benefit from the resistless fabrication. The fabricated nano-systems range from plasmonics and gratings for solar cells, electrical contacts for 2-D materials, transistor fabrication on planar and non-planar substrates, to magnetic nanostructures, plasmonic biosensing, cell and protein patterning, flexible devices, as well as the fabrication of NIL stamps and mass sensors integrated with CMOS. (C) 2014 Elsevier B.V. All rights reserved.

This paper shows thermal measurement and analysis of a microfluidic device integrated with local thin film heater. Thermal analysis was calculated by finite element modeling. Electrical property of the micro heater was calibrated in advance of the thermal analysis due to the difference from the bulk property of Pt. The thermal analysis results agreed well with experimental results. Our integrative approach suggests an importance of proper electrical measurement in micro heaters with Joule heating.

Resolving the various interactions of lipids and proteins in the plasma membrane of living cells with high spatiotemporal resolution is of upmost interest [1]. Here we introduce an innovative design of plasmonic nanogap antennas to monitor single-molecule events on model biological membranes at physiological relevant concentrations by means of fluorescence correlation spectroscopy. Our design involves the fabrication of in-plane plasmonic nanogap antennas arrays embedded in nanometric-size boxes to provide full surface accessibility of the hotspot-confined region. Using these antennas we recently reported fluorescence enhancement factors of 104-105 times on individual molecules diffusing in solution, together with nanoscale detection volumes in the zeptoliter range [2]. In principle, the planarity of these antennas should enable similar studies on biological membranes without unwanted membrane curvature effects. To show their applicability, we recorded the diffusion of individual molecules inserted in multi-component lipid bilayers as a simple mimetic system that recapitulates some of the most important features of cell membranes. We prepared membranes of different compositions: saturated phospholipids, sphingolipids and cholesterol and used antennas of different gap sizes (10-45 nm). The diffusion of individual molecules on membranes consisting of phospholipids and/or in a mixture with sphingolipids resulted Brownian, confirming homogenous lipid distribution. Interestingly, the strong confinement of antennas revealed the formation of transient (

Optical nanoantennas can efficiently confine light into nanoscopic hotspots, enabling single-molecule detection sensitivity at biological relevant conditions. This innovative approach to breach the diffraction limit offers a versatile platform to investigate the dynamics of individual biomolecules in living cell membranes and their partitioning into cholesterol-dependent lipid nanodomains. Here, we present optical nanoantenna arrays with accessible surface hotspots to study the characteristic diffusion dynamics of phosphoethanolamine (PE) and sphingomyelin (SM) in the plasma membrane of living cells at the nanoscale. Fluorescence burst analysis and fluorescence correlation spectroscopy performed on nanoantennas of different gap sizes show that, unlike PE, SM is transiently trapped in cholesterol-enriched nanodomains of 10 nm diameter with short characteristic times around 100 μs. The removal of cholesterol led to the free diffusion of SM, consistent with the dispersion of nanodomains. Our results are consistent with the existence of highly transient and fluctuating nanoscale assemblies enriched by cholesterol and sphingolipids in living cell membranes, also known as lipid rafts. Quantitative data on sphingolipids partitioning into lipid rafts is crucial to understand the spatiotemporal heterogeneous organization of transient molecular complexes on the membrane of living cells at the nanoscale. The proposed technique is fully biocompatible and thus provides various opportunities for biophysics and live cell research to reveal details that remain hidden in confocal diffraction-limited measurements.

To grow small molecule semiconductor thin films with domain size larger than modern-day device sizes, we evaporate the material through a dense array of small apertures, called a stencil nanosieve. The aperture size of 0.5 μm results in low nucleation density, whereas the aperture-to-aperture distance of 0.5 μm provides sufficient crosstalk between neighboring apertures through the diffusion of adsorbed molecules. By integrating the nanosieve in the channel area of a thin-film transistor mask, we show a route for patterning both the organic semiconductor and the metal contacts of thin-film transistors using one mask only and without mask realignment. ispartof: ACS Applied Materials and Interfaces vol:9 issue:28 pages:23314-23318 ispartof: location:United States status: published

Second harmonic generation (SHG) is an important tool for the study of plasmonic nanostructures and can open up important sensing applications since the second harmonic (SH) signal has an increased sensitivity to nanostructures shape and environment in comparison with the linear scattering [1,2]. SHG from plasmonic centrosymmetric nanostructures is controlled by two main properties. First, SHG is forbidden in the bulk of centrosymmetric structures in the dipolar approximation, meaning that nanostructures made of metals like gold and silver generate a SH signal coming mainly from their surfaces, where the symmetry is effectively broken. Second, because of the same symmetry reason, a dipolar excitation at the fundamental frequency induces SH modes with vanishing dipole moments [3]. In the case of plasmonic dimers, with the large intensity enhancement occurring in the gap, the SH emission is limited due to out-of-phase SH sources with destructive interferences in the far-field region. Consequently, new strategies must be developed to overcome this limitation.

While plasmonic antennas composed of building blocks made of the same material have been thoroughly studied, recent investigations have highlighted the unique opportunities enabled by making compositionally asymmetric plasmonic systems. So far, mainly heterostructures composed of nanospheres and nanodiscs have been investigated, revealing opportunities for the design of Fano resonant nanostructures, directional scattering, sensing and catalytic applications. In this article, an improved fabrication method is reported that enables precise tuning of the heterodimer geometry, with interparticle distances made down to a few nanometers between Au–Ag and Au–Al nanoparticles. A wide range of mode energy detuning and coupling conditions are observed by near field hyperspectral imaging performed with electron energy loss spectroscopy, supported by full wave analysis numerical simulations. These results provide direct insights into the mode hybridization of plasmonic heterodimers, pointing out the influence of each dimer constituent in the overall electromagnetic response. By relating the coupling of nondipolar modes and plasmon–interband interaction with the dimer geometry, this work facilitates the development of plasmonic heterostructures with tailored responses, beyond the possibilities offered by homodimers.

Nanoscale membrane assemblies of sphingolipids, cholesterol, and certain proteins, also known as lipid rafts, play a crucial role in facilitating a broad range of important cell functions. Whereas on living cell membranes lipid rafts have been postulated to have nanoscopic dimensions and to be highly transient, the existence of a similar type of dynamic nanodomains in multicomponent lipid bilayers has been questioned. Here, we perform fluorescence correlation spectroscopy on planar plasmonic antenna arrays with different nanogap sizes to assess the dynamic nanoscale organization of mimetic biological membranes. Our approach takes advantage of the highly enhanced and confined excitation light provided by the nanoantennas together with their outstanding planarity to investigate membrane regions as small as 10 nm in size with microsecond time resolution. Our diffusion data are consistent with the coexistence of transient nanoscopic domains in both the liquid-ordered and the liquid-disordered microscopic phases of multicomponent lipid bilayers. These nanodomains have characteristic residence times between 30 and 150 μs and sizes around 10 nm, as inferred from the diffusion data. Thus, although microscale phase separation occurs on mimetic membranes, nanoscopic domains also coexist, suggesting that these transient assemblies might be similar to those occurring in living cells, which in the absence of raft-stabilizing proteins are poised to be short-lived. Importantly, our work underscores the high potential of photonic nanoantennas to interrogate the nanoscale heterogeneity of native biological membranes with ultrahigh spatiotemporal resolution.

This paper reports and compares the implementation of magnetic variable optical attenuators (M-VOA) by two fabrication strategies. In the first case, a two-layer structure containing a non-doped polydimethylsiloxane (PDMS) layer on a magnetic PDMS (M-PDMS) layer is fabricated by soft lithography (SLT). M-PDMS is obtained by doping PDMS with different ferrofluid (FF) volumes. The second technology consists of selectively dispense FF microdroplets using the inkjet printing technique (UP) on a non-doped, non-cured PDMS structure, previously defined by SLT. In this second case, FF volumes are encapsulated inside the polymer matrix. The optical and mechanical properties of structures fabricated using both strategies and containing similar ferrofluid amounts are compared. (C) 2014 Elsevier B.V. All rights reserved.

Ionic liquids incorporating a polymerizable anion were prepared in a facile manner and used to fabricate stable titania nanoparticle films. The nanotitania was directly patterned by UV imprinting using micrometer size test structures in a polydimethylsiloxane mold. The resulting resist microstructures are resistant to cracking with only slight shrinkage observed for the system made using a hydrophobic ionic liquid. Because ionic liquids with a plethora of different physical and chemical properties can be made (designed) in a facile manner their application in this facile process instead of organic solvents could lead to many new types of functional materials.

Planar lithography techniques are not effective for precise fabrication of microdevices with hemispherical shapes. Drop-on-demand (DOD) inkjet printing (IJP) of photo-curable ink is a more appropriate fabrication approach as it takes advantage of the surface tension as well as of the delivery of a well-defined ink volume. Described is a DOD IJP technique onto geometrically-patterned silicon substrates enabling the controlled fabrication of SU-8 hemispherical microcapsules. Open half capsules of 100 µm in diameter with inner cavity volumes of 5, 20 and 45 pl with a printing yield above 96% are demonstrated. The same technique is directly adapted to the fabrication of microcapsules embedding silicon microchips. The reported findings open new paths for controlled encapsulation of liquids into smart microsystems.

In this paper, a two-dimensional nanometer scale tip-plate discharge model has been employed to study nanoscale electrical discharge in atmospheric conditions. The field strength distributions in a nanometer scale tip-to-plate electrode arrangement were calculated using the finite element analysis (FEA) method, and the influences of applied voltage amplitude and frequency as well as gas gap distance on the variation of effective discharge range (EDR) on the plate were also investigated and discussed. The simulation results show that the probe with a wide tip will cause a larger effective discharge range on the plate; the field strength in the gap is notably higher than that induced by the sharp tip probe; the effective discharge range will increase linearly with the rise of excitation voltage, and decrease nonlinearly with the rise of gap length. In addition, probe dimension, especially the width/height ratio, affects the effective discharge range in different manners. With the width/height ratio rising from 1:1 to 1:10, the effective discharge range will maintain stable when the excitation voltage is around 50 V. This will increase when the excitation voltage gets higher and decrease as the excitation voltage gets lower. Furthermore, when the gap length is 5 nm and the excitation voltage is below 20 V, the diameter of EDR in our simulation is about 150 nm, which is consistent with the experiment results reported by other research groups. Our work provides a preliminary understanding of nanometer scale discharges and establishes a predictive structure-behavior relationship.

We demonstrate theoretically and experimentally the possibility to achieve the strong coupling regime at room temperature with a microwave electronic oscillator coupled with an ensemble of electron spins. The coupled system shows bistable behaviour, with a broad hysteresis and sharp transitions. The coupling strength and the hysteresis width can be adjusted through the number of spins in the ensemble, the temperature, and the microwave field strength.

We fabricated amorphous silicon n-i-p solar cells with two types of nanopatterned back reflectors using stencil lithography. One reflector type has a plasmonic grating that is embedded in the ZnO layer; the other one has a metallic grating patterned on top of the Ag layer. From comparing the short-circuit current densities of the two device types, we conclude that light trapping through grating coupling is more efficient than coupling of light through the excitation of localized surface plasmons. The back reflectors were patterned with dot arrays by evaporation of Ag through millimeter-size stencil membranes. The stencils themselves were patterned by wafer-scale nanosphere lithography. The dot arrays have a periodicity of 428 nm and efficiently scatter light in the near-infrared wavelength range. Both back reflectors types lead to the same morphology for the silicon films. This allows us a fair comparison of the two light coupling mechanisms. We found a 14% and 19% short-circuit current density enhancement for the plasmonic and for the metallic grating, respectively. The external quantum efficiency gains between 550 and 650 nm show similar guided modes resonances for both device types, but the excitation is stronger for the device with the metallic grating.

The application of Au/Si3N4 stencil masks for the transfer of patterns using different MeV-ion beams with various substrates has been investigated. The techniques investigated were namely, conventional lithography with positive- and negative-tone resist polymers, oxygen ion-induced etching of PTFE and patterning using an etch-stop in silicon. We demonstrate that using different well-known microtechnology material-modification techniques, patterns can be transferred using stencil masks and broad ion beams to nanomachining scenarios. In the case of the etch-stop process; writing of 3D micropatterns with different height levels was achieved using a broad beam. The stencil masks were found to be durable with no obvious deterioration and well suited for exposure of large areas. (C) 2013 Elsevier B.V. All rights reserved.

Electron energy-loss spectroscopy (EELS) has become an experimental method of choice for the investigation of localized surface plasmon resonances, allowing the simultaneous mapping of the associated field distributions and their resonant energies with a nanoscale spatial resolution. The experimental observations have been well-supported by numerical models based on the computation of the Lorentz force acting on the impinging electrons by the scattered field. However, in this framework, the influence of the intrinsic properties of the plasmonic nanostructures studied with the electron energy-loss (EEL) measurements is somehow hidden in the global response. To overcome this limitation, we propose to go beyond this standard, and well-established, electron perspective and instead to interpret the EELS data using directly the intrinsic properties of the nanostructures, without regard to the force acting on the electron. The proposed method is particularly well-suited for the description of coupled plasmonic systems, because the role played by each individual nanoparticle in the observed EEL spectrum can be clearly disentangled, enabling a more subtle understanding of the underlying physical processes. As examples, we consider different plasmonic geometries in order to emphasize the benefits of this new conceptual approach for interpreting experimental EELS data. In particular, we use it to describe results from samples made by traditional thin film patterning and by arranging colloidal nanostructures.

cited By 2; International audience; We report on photo-current generation in freestanding monolayered gold nanoparticle membranes excited by using a focused laser beam. The absence of a substrate leads to a 50% increase of the photo-current at the surface plasmon resonance. This current is attributed to a combination of trap state dynamics and bolometric effects in a nanocomposite medium yielding a temperature rise of 40 K.

We present a novel triboelectric nanogenerator (TENG) based on a paper-Teflon configuration fabricated by an easy and cost-efficient process. Carbon electrodes were hand-drawn by means of a graphite pencil on commercial paper cards, and the conductivity was confirmed by multimeter. In order to increase the effective triboelectric area, we used sandpaper imprinting to increase the surface roughness more than 2-fold compared to flat surfaces yielding a more than 6-fold enhancement of power density. The achieved output voltage, current and power density were ∼55 V, ∼2.5 μA and ∼17 μW/cm2, respectively. The arch-shaped TENG shows robust output power when pressed by fingers to power a 2-bit liquid crystal display (LCD) demonstrating its use as energy harvester based on low-cost, commodity materials such as paper, Teflon and graphite.

cited By 0; Conference of 11th IEEE Nanotechnology Materials and Devices Conference, NMDC 2016 ; Conference Date: 9 October 2016 Through 12 October 2016; Conference Code:125383; International audience; We report on photo-current generation in freestanding monolayered gold nanoparticle membranes excited by using a laser. The absence of a substrate leads to a 50% increase of the photocurrent at plasmon resonance. This current is attributed to a combination of trap state dynamics and bolometric effects in a nanocomposite medium yielding a temperature rise of 40K.

Quaternary semiconductor Cu2ZnSnSe4 (CZTSe) is a very promising alternative to semiconductors based on indium (In) and gallium (Ga) as solar absorber material due to its direct band gap, inherent high absorption coefficient (>104 cm−1) and abundance of cheap elements zinc (Zn) and tin (Sn). In this study, high quality CZTSe thin films were successfully synthesized by a green and low-cost solution based non-vacuum method, which involves spin coating non-toxic solvent-based CZTSe nano-inks onto Mo coated soda lime glass substrates followed by selenization with elemental Se vapor. The effect of selenization temperature on structural, morphological, compositional and optical properties of CZTSe films are investigated using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and photoluminescence spectroscopy. XRD and Raman analysis indicates that a tetragonal stannite-type structured CZTSe is formed. Depend on the selenization temperature, the dense and compact films with grain sizes from 200 nm (500 °C) up to about 1 μm (580 °C) are obtained. EDS measurement indicates that the composition ratios of the prepared CZTSe films are copper-poor and zinc-rich nature. The CZTSe films are p-type conductivity confirmed by a hot point probe method. Photoluminescence spectrum shows slightly asymmetric narrow bands with a maximum of intensity at 0.92 eV. The dependence of the photoluminescence on the excitation temperature reveals a decrease in the intensity of the photoluminescence bands. An absorption coefficient exceeding 104 cm−1 and the band gap energy about 0.87 eV of the studied films are determined by an absorption spectroscopy.

We report for the first time the results of tensile stress testing of thin film conductive structures patterned by stencil lithography on a PI substrate. The goal of this investigation is to determine the effects that mechanical deformation occurring in real applications can have on electrical parameters of metal interconnects in flexible electronic circuits. The thickness of thin film gold conductors is of the order of 10 nm while their lateral dimensions are in the micrometer range. Electrical parameters of thin film conductors are measured under uniaxial tensile stress and in the relaxed state after subjecting them to a number of stretching and relaxation cycles. SEM imaging of the test structures was used for observing of possible changes in thin film surface morphology caused by the applied tensile stress. © 2012 Elsevier B.V. All rights reserved.