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Manipulation and Deposition of Complex, Functional Block Copolymer Nanostructures using Optical Tweezers
摘要： Block copolymer self-assembly has enabled the creation of a range of solution-phase nanostructures with applications from optoelectronics and biomedicine to catalysis. However, to incorporate such materials into devices a method that facilitates their precise manipulation and deposition is desirable. Herein we describe how optical tweezers can be used to trap, manipulate, and pattern individual cylindrical micelles and larger hybrid micellar materials. Through the combination of TIRF imaging and optical trapping we can precisely control the three-dimensional motion of individual cylindrical block copolymer micelles in solution, enabling the creation of customizable arrays. We also demonstrate that dynamic holographic assembly enables the creation of ordered customizable arrays of complex hybrid block copolymer structures. By creating a program which automatically identifies, traps and then deposits multiple assemblies simultaneously we have been able to dramatically speed up this normally slow process, enabling the fabrication of arrays of hybrid structures containing hundreds of assemblies in minutes rather than hours.
关键词： optical trapping,directed assembly,block copolymers,self-assembly,nanofibers
更新于2025-11-21 11:24:58
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Self-assembled indium nanostructures formation on InSe (0001) surface
摘要： The surfaces of 2D layered crystals are one among most perspective templates for self-assembling of metal nanostructures due to the dewetting. The initial InSe (0001) surface as topological template was characterized by means of scanning tunneling microscopy/spectroscopy (STM/STS) and low electron energy diffraction. InSe (0001) surface used in the process of formation of nanostructures found to be a template covered with array of triangular-shaped cites. The results of STM/STS studies on the formation of indium nanostructures on (0001) surface of InSe layered semiconductor crystal are presented. Indium was thermally deposited on structurally perfect InSe crystal cleavages obtained in situ. Geometrically heterogeneous (in height) initial (0001) InSe surface is used to activate the dewetting phenomenon in a manner that leads to the formation of 0D triangular-shaped nucleus of deposited indium nanostructures. STS acquired spatially averaged I–V curves changes their dependence from semiconductor one to almost metallic due to dewetting process. Moreover, the spatial arrangement of formed indium nanostructures is powered by hexagonal lattice symmetry of InSe surface on macroscale.
关键词： Hetero nanostructures,Nanostructures template-directed assembly,Layered crystals,Scanning tunneling microscopy/spectroscopy,Indium selenide,Low energy electron diffraction
更新于2025-09-23 15:21:01
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Assembly of Conductive Polyaniline Microstructures by a Laser-Induced Microbubble
摘要： Micro-patterns of conductive polymers are key for various applications in the fields of flexible electronics and sensing. A bottom-up method that allows high-resolution printing without additives is still lacking. Here, such a method is presented based on micro-printing by the laser-induced microbubble technique (LIMBT). Continuous micro-patterning of polyaniline (PANI) was achieved from a dispersion of the Emeraldine base form of PANI (EB-PANI) in n-methyl-2-pyrrolidone (NMP). A focused laser beam is absorbed by the EB-PANI nanoparticles and leads to formation of a microbubble, followed by convection currents, which rapidly pin EB-PANI nanoparticles to the bubble/substrate interface. Micro-Raman spectra confirmed that the printed patterns preserve the molecular structure of EB-PANI. A simple transformation of the printed lines to the conducting Emeraldine salt form of PANI (ES-PANI) was achieved by doping with various acid solutions. The hypothesized deposition mechanism was verified, and the resulting structures were characterized by microscopic methods. The micro-structures displayed conductivity of 3.8×10-1 S/cm upon HCl doping and 1.5×10-1 S/cm upon H2SO4 doping, on par with state-of-the-art patterning methods. High fidelity control over the width of the printed lines down to ~650 nm was accomplished by varying the laser power and microscope stage velocity. This straightforward bottom-up method using low power lasers offers an alternative to current microfabrication techniques.
关键词： laser printing,nanoparticle assembly,polyaniline,microbubble,directed assembly
更新于2025-09-23 15:19:57
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Solution-processed organic field-effect transistors using directed assembled carbon nanotubes and 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT)
摘要： Achieving low-cost fabrication of organic field-effect transistors (OFETs) has long been pursued in the semiconductor industry. Solution-based process allows the fabrication of OFETs cost-effective because of its merit of vacuum-free and room temperature operation. Here, we show a facile and scalable fabrication of solution-processed OFETs using carbon nanotube (CNT) as source/drain electrodes and 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) as semiconducting layer on silicon as well as on flexible and transparent polyethylene terephthalate (PET) substrates. The CNT electrodes and the C8-BTBT film are fabricated using a dip coating-based directed assembly process, and two dip coating parameters, the pulling speed and the solution concentration, are carefully chosen so that the thickness of the C8-BTBT film is close to that of the CNT electrodes. The fabricated OFET devices show typical p-channel behavior. Low-cost, ease of processing, wafer level scalability and good compatibility with various substrates make the fabrication process presented in this paper well suited for next-generation electronics and sensors.
关键词： carbon nanotube,C8-BTBT,directed assembly,transistor
更新于2025-09-19 17:13:59
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Nanoline-gap controlled self assembly of plasmonic nanoparticles inside plasmonic nanolines
摘要： This paper presents plasmonic substrates fabricated by a gap-controlled, template-assisted self assembly of plasmonic nanoparticles ? such as spherical nanoparticles and nanorods ? inside one dimensional plasmonic nanoline templates fabricated using Deep-UV lithography. This hybrid fabrication process ? which combines the bottom-up process of capillary-force self assembly with the top-down process of Deep-UV lithography ? can potentially be employed for large-area fabrication (6 inch or 12 inch wafers) of plasmonic substrates with sub-10 nm gaps. These small gaps lead to a high electromagnetic enhancement which can be highly beneficial if these substrates are employed for sensing based on surface enhanced Raman scattering (SERS). We demonstrate that the templates of plasmonic nanolines act as lithographed traps and direct the capillary-force assembly of metallic nanoparticles. The gaps between the nanolines, along with the shape and dimensions of the nanoparticles, together determine the interparticle distance, packing pattern and the orientation of the assembled nanoparticles inside these nanolines. Moreover, the electromagnetic behavior of these substrates is exhaustively analyzed using Finite Difference Time Domain (FDTD) modeling. Thus, we demonstrate template-directed, capillary-force assembly of plasmonic nanoparticles inside plasmonic nanolines such that the assembly can be controlled by modulating the structural parameters of the template or the assembled nanoparticles, and can be potentially carried out on a large area.
关键词： self-assembly,nanoparticles,nanorods,plasmonics,template-directed assembly
更新于2025-09-12 10:27:22
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Electrostatic Directed Assembly of Colloidal Microparticles Assisted by Convective Flow
摘要： Electrostatic directed assembly of colloidal particles on charged patterns, i.e. nanoxerography, has proven to find innovative applications in plasmonics, anticounterfeiting or particle sorting. However, this technique was restricted to dispersions of nanoparticles whose diameters are typically below 100nm. The combination of experiments and simulations shows that this limitation is due to an uncontrolled dewetting of the substrate and to the small mobility of large particles. The “convective nanoxerography” process developed in this work overcomes this limit and allows making selective and dense assemblies of micron-sized particles, expanding by a factor 40 the size range foreseeable.
关键词： colloidal microparticles,Electrostatic directed assembly,nanoxerography,micron-sized particles,convective flow
更新于2025-09-09 09:28:46