Introducing surface functionality on thermoformed polymeric films

Altres ajuts: this work has been performed within the PLASTFUN project (Planta Pilot de Peces Plàstiques amb Superficies Funcionals Avançades), within the Industries of the Future community (IDF) RIS3CAT, supported by the European Regional Development Fund (ERDF) as part of the operative frame FEDER of Catalonia 2014-2020 EC [COMRDI 16-1-0018], included in the 7th Framework Program. AF, NK and CMST acknowledge support from the CERCA Programme of the Generalitat de Catalunya.We present a fabrication process for the production of 3-dimensional micro-structured polymeric films. The microstructures are fabricated in a single step using thermal nanoimprint lithography as patterning technique. The micro-structured polymer films are then transformed into a 3D shape by means of a plug-assisted thermoforming process, while keeping the functionality of the micro-patterned areas. The preserved functionality is characterized by water contact angle measurements, while the deformation of the micro-structured topographies due to the thermoforming process is analyzed using confocal microscopy and Digital Image Correlation (DIC) techniques. This combined fabrication process represents a promising solution to complement in-mold decoration approaches, enabling the production of new functional surfaces. As the microstructures are fabricated by means of a mechanical modification of the surface, without the need of chemical treatments or coatings, the presented technique represents a promising, simple and green solution, suitable for the industrial fabrication of 3D nonplanar shaped functional surfaces

Simulation of low energy ion layering in carbon nanotubes

This study simulates the passage of low-energy ions through carbon nanotubes in channeling mode. It is shown that taking into account the deformation of the wall of a carbon nanotube when calculating the interaction of ions with the nanotube wall leads to a decrease in ion energy losses in the case when the longitudinal velocity of the ion motion and perturbations of the nanotube wall are close in magnitude

Plasmonic Optical Sensors: Performance Analysis and Engineering Towards Biosensing

Surface plasmon resonance (SPR) sensing for quantitative analysis of chemical reactions and biological interactions has become one of the most promising applications of plasmonics. This thesis focuses on performance analysis for plasmonic sensors and implementation of plamonic optical sensors with novel nanofabrication techniques. A universal performance analysis model is established for general two-dimensional plasmonic sensors. This model is based on the fundamental facts of surface plasmon theory. The sensitivity only depends on excitation light wavelength as well as dielectric properties of metal and dielectrics. The expression involves no structure-specified parameters, which validates this formula in broad cases of periodic, quasiperiodic and aperiodic nanostructures. Further analysis reveals the intrinsic relationship between plamonic sensor performance and essential physics of surface plasmon. The analytical results are compared to the sensitivities of previously reported plasmonic sensors in the field. This universal model is a promising qualification criterion for plasmonic sensors. Plasmonic optical sensors are engineered into high-performance on-chip sensors, plasmonic optical fibers and freestanding nanomembranes. (1) Periodic nanohole arrays are patterned on chip by a simple and robust template-transfer approach. A spectral analysis approach is also developed for improving the sensor performance. This sensor is applied to demonstrate the on-chip detection of cardiac troponin-I. (2) Plasmonic optical fibers are constructed by transferring periodic metal nanostructures from patterned templates onto endfaces of optical fibers using an epoxy adhesive. Patterned metal structures are generally extended from nanohole arrays to nanoslit arrays. A special plasmonic fiber is designed to simultaneously implement multimode refractive index sensing with remarkably narrow linewidth and high figure of merit. A real-time immunoassay relying on plasmonic fiber is demonstrated. Plasmonic optical fibers also take advantages of consistent optical responses, excellent stability during fiber bending and capability of spectrum filtering. (3) Large-area freestanding metal nanomembranes are implemented using a novel fabrication approach. The formed transferrable membranes feature high-quality and uniform periodic nanohole arrays. The freestanding nanomembranes exhibit remarkably higher transmission intensity in comparison to the nanohole arrays with same features on the substrate. These three modalities of plasmonic sensors possess different applicability to fulfill various plasmonic sensing tasks in respective scenarios

DEVELOPING NANOPORE ELECTROMECHANICAL SENSORS WITH TRANSVERSE ELECTRODES FOR THE STUDY OF NANOPARTICLES/BIOMOLECULES

This study concerns development of a technology of utilizing metallic nanowires for a sensing element in nanofluidic single molecular (nanoparticle) sensors formed in plastic substrates to detect the translocation of single molecules through the nanochannel. We aimed to develop nanofluidic single molecular sensors in plastic substrates due to their scalability towards high through and low cost manufacturing for point-of-care applications. Despite significant research efforts recently on the technologies and applications of nanowires, using individual nanowires as electric sensing element in nanofluidic bioanalytic devices has not been realized yet. This dissertation work tackles several technical challenges involved in this development, which include reduction of nanowire agglomerates in the deposition of individual nanowires on a substrate, large scale alignment/assembly of metallic nanowires, placement of single nanowires on microelectrodes, characterization of electrical conductance of single nanowire, bonding of a cover plate to a substrate with patterned microelectrodes and nanowire electrodes. Overcoming the abovementioned challenges, we finally demonstrated a nanofluidic sensor with an in-plane nanowire electrode in poly(methyl methacrylate) substrates for sensing single biomolecules. In the first part of this study, we developed the processes for separation and large-scale assembly of individual NiFeCo nanowires grown using an electrodeposition process inside a porous alumina template. A method to fabricate microelectrode patterns on plastic substrates using flexible stencil masks was developed. We studied electrical and magnetic properties of new composite core-shell nanowires by measuring the electrical transport through individual nanowires. The core-shell nanowires were composed of a mechanically stable FeNiCo core and an ultrathin shell of a highly conductive Au gold (FeNiCo-Au nanowires). In the second part of this study, we simulated the effects of the nanopore geometry on the current drop signal of the translocation through a nanopore via finite element method using COMSOL. Using the above techniques, we developed for the fabrication and alignment of the microelectrodes and nanowires, we studied the optimum conditions to integrate the transverse nanoelectrode with the nanochannel on plastic substrates. The main challenge was to find the conditions to embed the micro-/nanoelectrodes into the nanochannel substrate as well as the nanochannel cover sheet

Integration of Micro Patterning Techniques into Volatile Functional Materials and Advanced Devices

Novel micro patterning techniques have been developed for the patterning of volatile functional materials which cannot be conducted by conventional photolithography. First, in order to create micro patterns of volatile materials (such as bio-molecules and organic materials), micro-contact printing and shadow mask methods are investigated. A novel micro-contact printing technique was developed to generate micro patterns of volatile materials with variable size and density. A PDMS (Polydimethylsiloxane) stamp with 2-dimensional pyramidal tip arrays has been fabricated by anisotropic silicon etching and PDMS molding. The variable size of patterns was achieved by different external pressures on the PDMS stamp. A novel inking process was developed to enhance the uniformity and repeatability in micro-contact printing. The variable density of patterns could be obtained by alignment using x-y transitional stage and multiple stamping with a z-directional moving part. Second, for direct patterning of small molecule organic materials (e.g. pentacene), a novel shadow mask method has been developed with a simple and accurate alignment system. To make accurate dimensions of patterning windows, a silicon wafer was used for the shadow mask since a conventional semiconductor process gives a great advantage for accurate and repeatable fabrication processes. A sphere ball alignment system was developed for the accurate alignment between the shadow mask and the silicon substrate. In this alignment system, four matching pyramidal cavities were fabricated on each side of the shadow mask and silicon wafer substrate using an anisotropic silicon bulk etching. By placing four steel spheres in between the matching cavities, the self-alignment system could be demonstrated with 2-3um alignment accuracy in x-y directions. For OTFT (Organic thin film transistor) application, an organic semiconducting layer was directly deposited and patterned on the substrate using the developed shadow mask method. On the other hand, novel embedding techniques were developed for enabling conventional semiconductor processes including photolithography to be applied on the small substrate. The polymer embedding method was developed to provide an extended processing area as well as easy handling of the small substrate. As an application, post CMOS (Complementary metal-oxide-semiconductor) integration of a relatively large microstructure which might be even larger than the substrate was demonstrated on a VCO (Voltage-controlled oscillator) chip. In addition, micro patterning on the optical fiber was demonstrated by using a silicon wafer holder designed to surround and hold the optical fiber. The micro Fresnel lens could be successfully patterned and integrated on the optical fiber end

Organic Electronics With Polymer Dielectrics On Plastic Substrates Fabricated Via Transfer Printing

Printing methods are fast becoming important processing techniques for the fabrication of flexible electronics. Some goals for flexible electronics are to produce cheap, lightweight, disposable radio frequency identification (RFID) tags, very large flexible displays that can be produced in a roll-to-roll process and wearable electronics for both the clothing and medical industries. Such applications will require fabrication processes for the assembly of dissimilar materials onto a common substrate in ways that are compatible with organic and polymeric materials as well as traditional solid-state electronic materials. A transfer printing method has been developed with these goals and application in mind. This printing method relies primarily on differential adhesion where no chemical processing is performed on the device substrate. It is compatible with a wide variety of materials with each component printed in exactly the same way, thus avoiding any mixed processing steps on the device substrate. The adhesion requirements of one material printed onto a second are studied by measuring the surface energy of both materials and by surface treatments such as plasma exposure or the application of self-assembled monolayers (SAM). Transfer printing has been developed within the context of fabricating organic electronics onto plastic substrates because these materials introduce unique opportunities associated with processing conditions not typically required for traditional semiconducting materials. Compared to silicon, organic semiconductors are soft materials that require low temperature processing and are extremely sensitive to chemical processing and environmental contamination. The transfer printing process has been developed for the important and commonly used organic semiconducting materials, pentacene (Pn) and poly(3-hexylthiophene) (P3HT). A three-step printing process has been developed by which these materials are printed onto an electrode subassembly consisting of previously printed electrodes separated by a polymer dielectric layer all on a plastic substrate. These bottom contact, flexible organic thin-film transistors (OTFT) have been compared to unprinted (reference) devices consisting of top contact electrodes and a silicon dioxide dielectric layer on a silicon substrate. Printed Pn and P3HT TFTs have been shown to out-perform the reference devices. This enhancement has been attributed to an annealing under pressure of the organic semiconducting material

Programmable chiral nanocolloids

Nanoparticles promise a variety of application in energy, medicine, and biology. However, most nanoparticlesâ material composition and shape cannot be tuned and so functions have thus far been limited. Moreover they are often also chemically unstable in solution. Therefore, the overall goal of this thesis is to develop nanoparticles whose function and shape can be programmed and that can be corrosion protected, and to then apply these nanoparticles to sensing tasks in complex biological fluids. A special focus of this thesis is chiral nanostructures. A promising technique to address this is physical vapour shadow growth, namely nano glancing angle depo-sition (nanoGLAD). This scheme allows the design of new three-dimensional (3D) hybrid nanoparticles as it permits the control over both the shape and material composition of the nanoparticles. Although this method offers the possibility to grow nanoparticles that are functionally programmed, it has so far not al-lowed the use of many materials that are chemically unstable in solution, which limits the scope of poten-tial applications. This thesis starts with describing the nanoGLAD growth procedure. A first application is the wafer-scale patterning of unconventional nanoshapes, e.g. tri-layer particles, holes, rings, and hollow domes, which are not possible using state of the art 3D nanofabrication methods (chapter 2). Then, in conjunction with atom-ic layer deposition (ALD), this thesis shows how the nanoGLAD scheme can be adapted for the fabrication of â3D core-shell nanoparticles and nanocolloidsâ using unstable and reactive materials. The key concept here is that the core consists of the unstable material which is grown such that the shell contains no voids or defects (chapter 3). Notably, the shapes that can be grown include symmetry-broken chiral nanoparti-cles, which possess unique spectral properties that make them useful for sensing applications. This thesis uses chiral nanocolloids to realise extremely sensitive plasmonic nanosensors and nanocolloids that can also be used as a nanomechanical probes for active nanorheology. By forming a composite of two materials during growth â one that gives a strong plasmonic response and the other to tune the compositeâs dielec-tric function â plasmonic nanoparticles are presented that show record local surface plasmon resonance (LSPR) sensitivities to date (chapter 4). With the same alloying principle a plasmonic and a ferromagnetic material are combined. The resulting âchiral + plasmonic + ferromagneticâ particles can be actuated using a magnetic field and this is used to measure the viscosity of blood plasma in the presence of blood cells. The viscosity of blood serum is an important disease indicator, but the measurement using commercial rheome-ters requires the separation of the blood cells. This is not needed in the nanorheological measurements shown in this thesis (chapter 5)

Wafer-Scale Fabrication of Thin SiN Membranes and Au Films and Membranes with Arrays of Sub-um Holes Using Nanosphere Lithography

In this thesis, the wafer-scale fabrication of SiN membranes, Au films and Au membranes with arrays of sub-µm holes is described. Two conceptually different processes (1) and (2) were developed, both of which are based on nanosphere lithography (NSL) with self-assembled close-packed monolayers of polystyrene (PS) beads. PS beads with a diameter D in the range of 420 nm to 530 nm were used. The hole array periodicity p was thus determined by D. Different bead deposition methods were tested; by spin-coating, a monolayer wafer coverage > 90% could be obtained. By O2-RIE, D could be reduced in a controlled way down to 0.3D. In process (1), holes were etched into the device layer using a hole etch mask made by NSL. The hole size ⌀ was determined by the reduced D. In this way, 100 nm thick SiN membranes with a maximum size of 2400×2400 µm2 and a hole density on the order of 108 holes/cm2 were fabricated by etching holes into the SiN. The membrane release was done in a combined dry-/wet-etch procedure. Similarly, hole arrays were fabricated on 2" glass wafers by sputter-etching into 200 nm thick Au films. With this process, different ⌀, e.g. from 60 nm to 180 nm, could be obtained for initially identical mask holes by tuning the sputter-etch parameters. In process (2), NSL was used to realize high aspect ratio Si and oxidized Si pillars that were subsequently used as a lift-off template. Free-standing, 200 nm thick, 1200◊1200 µm2 large Au membranes with ⌀ from 100 nm to 300 nm were successfully fabricated using Si pillars as KOH lift-off template and a Si-DRIE release procedure. Using oxidized Si pillars for lift-off in HF instead, such hole arrays in Au films could be transferred to flexible, transparent parylene films. The fabricated devices were characterized and successfully tested for stencil and refractive index sensing applications: Holey SiN membranes were bulge-tested and withstood pressures up to 5 bar, showing their suitability for stencil and filtration applications. Stenciling was successfully done for (a) the deposition of arrays of 230 nm in diameter Au and Ag dots onto Si substrates and (b) the etching of holes into a 500 nm thick SiN membrane. The light transmission characteristics of wafer-scale hole arrays in Au films were reproducible for different measurement locations. Similar hole arrays were used to detect refractive index changes in water of varying glycerine concentrations. The transmission through Cr/Au membranes with sub-wavelength hole arrays was measured. Upon Cr removal, the transmission was enhanced by a factor 2.4

Focused ion beam technology : implementation in manufacturing platforms and process optimisation

Process chains are regarded as viable manufacturing platforms for the production of Microand Nano Technology (MNT) enabled products. In particular, by combining several manufacturing technologies, each utilised in its optimal process window, they could benefit from the unique advantages of high-profile research technologies such as the focused ion beam (FIB) machining. The present work concerns the development of process chains and the investigation of pilot cost-effective implementations of the FIB technology in manufacturing platforms forfabrication of serial replication masters.EThOS - Electronic Theses Online ServiceGBUnited Kingdo