The authors would like to thank Professor Yuzuru Takashima at the University of Arizona for discussions on optical imaging, Mr. Karl Urbanek for assistance with high power lasers, and Max Yuen for discussions of Brownian motion. The authors send further thanks to Professor Kenneth Crozier at Harvard University for helpful discussions on optical trapping experiments. Funding was provided in part by the United States National Science Foundation (award number 1028372).

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The authors have nothing to disclose.

O NOCB combina as forças de armadilhagem fortes e tamanho pequeno armadilha de abordagens plasmonic com a capacidade para o transporte de partículas, a longo disponível somente para as técnicas de feixe focalizado convencionais. Exclusivo para o NOCB, as propriedades de captura e transporte do sistema são o resultado de padrões de superfície e não de moldar o feixe de iluminação. Desde que a iluminação é brilhante o suficiente e sua polarização ou comprimento de onda pode ser modulada, as partículas pode...

Capture, interrogatório e manipulação de nanopartículas individuais são de importância crescente na nanotecnologia. Pinças ópticas tornaram-se uma técnica de manipulação particularmente bem sucedido para experimentos em biologia molecular 1-4, 5-7 e química nano-montagem 7-10, onde eles permitiram que experiências inovadoras, tais como a medição das propriedades mecânicas de moléculas de DNA de solteiro 4 e a ordenação das células por suas propriedades ópticas 11,12. Descobertas sobre essas fronteiras abrir o estudo de sistemas ainda menores, e eles abrir caminho para a engenharia de novos produtos e técnicas praticamente benéficos. Por sua vez, esta tendência impulsiona a necessidade de novas técnicas para manipular mais rudimentares, partículas menores. Além disso, há uma pressão para construir dispositivos &quot;lab-on-a-chip&quot; para executar essas funções de forma mais barata e numa embalagem mais pequena, a fim de trazer os testes químicos e biológicos para fora dolaboratório e no campo para médicos e outros fins 13,14. Infelizmente, captura óptica convencional (COT) não pode atender a todas as demandas de crescimento da nanotecnologia. COT opera sobre o mecanismo de utilizar uma elevada abertura numérica (NA) lente objectiva para trazer luz laser para um foco apertado, criando um pico localizado em intensidade óptica e gradientes elevados em energia do campo electromagnético. Estes gradientes de densidade de energia exercem uma força resultante sobre partículas de dispersão da luz que geralmente chama-los em direcção ao centro do foco. Prendendo partículas menores exige potência óptica superior ou um foco mais apertado. No entanto, os feixes de luz focalizado obedecer o princípio da difracção, que limita o tamanho mínimo do ponto focal e coloca um limite superior do gradiente de densidade de energia. Isso tem duas consequências imediatas: COT não pode reter pequenos objetos de forma eficiente, e COT tem dificuldade para discriminar entre as partículas espaçados, uma resolução trappinglimitação conhecida como o problema dos dedos gordos &quot;. Além disso, a implementação de múltiplos aprisionamento de partículas com COT requer sistemas de óptica de orientação de feixe de luz ou moduladores espaciais, componentes que aumentam drasticamente o custo ea complexidade de um sistema de captura óptica. Uma maneira de contornar as limitações fundamentais de vigas focadas convencionais de luz, disse a propagar no campo agora, é a vez explorar os gradientes de energia eletromagnética óptica no campo próximo. O próximo campo decai exponencialmente a partir de fontes fora dos campos electromagnéticos, o que significa que não só é altamente localizada a estas fontes, mas também exibe muito elevados gradientes na sua densidade de energia. Os próximos campos de ressonadores nano-metálicos, como aberturas bowtie, nano colunas e as gravuras em forma de C, foram mostrados para expor extraordinária concentração de energia eletromagnética, reforçada pela ação plasmonic de ouro e prata a quase infrcomprimentos de onda ópticos e ARED. Estes ressoadores ter sido usado para prender partículas extremamente pequenas com elevada eficiência e resolução 15-22. Embora esta técnica tem se mostrado eficaz na captura de partículas pequenas, ele também provou ser limitado em sua capacidade para o transporte de partículas sobre a escala apreciável, o que é necessário se os sistemas de campo próximo são a interface com sistemas de campo distante ou microfluídica. Recentemente, o nosso grupo propôs uma solução para este problema. Quando ressonadores são colocados muito próximos entre si, uma partícula pode, em princípio, migrar de um campo próximo armadilha óptica para o próximo sem ser liberado a partir da superfície. A direcção do transporte pode ser determinado se armadilhas adjacentes podem ser ligados e desligados separadamente. Uma cadeia linear de três ou mais ressonadores endereçáveis, em que cada um ressonador é sensível a um comprimento de onda ou polarização de luz diferente da dos seus vizinhos, funciona como uma correia transportadora óptico, o transporte de nanopartiCiclos mais de uma distância de alguns micra num chip. O chamado &#39;Nano-óptica Correia Transportadora&#39; (NOCB) é único entre os regimes de ressonador de armadilhagem plasmonic, como não só ele pode conter partículas no lugar, mas também pode movê-los em alta velocidade ao longo das trilhas estampados, reunir ou dispersar as partículas, misturar e fila-los, e até mesmo classificá-los por propriedades, tais como a sua mobilidade 23. Todas estas funções são controladas através da modulação do comprimento de onda ou polarização de iluminação, sem necessidade de óptica de orientação de feixe. Como uma armadilha óptica de campo próximo, o NOCB prendendo resolução é maior do que a de armadilhas ópticas de feixe focado convencionais, de modo que pode diferenciar entre as partículas em estreita proximidade; porque ele usa uma nanoestrutura metálica para concentrar a luz em um prendendo bem, é eficiente em termos de energia, e não requer componentes ópticos caros, como um objectivo elevado NA. Além disso, muitos NOCBs podem ser operados em paralelo, com alto embalagem densidade, no mesmo substrato, e um W de potência pode dirigir mais de 1200 aberturas 23. Temos demonstrado recentemente o primeiro NOCB-driven polarização, sem problemas impulsionando uma nanopartícula frente e para trás ao longo de uma faixa de 4,5 mm 24. Neste artigo apresentamos os passos necessários para projetar e fabricar o dispositivo, opticamente ativá-lo e reproduzir o experimento de transporte. Esperamos que a esta técnica mais amplamente disponível vai ajudar a preencher a lacuna entre a óptica tamanho microfluídica, em campo distante e dispositivos em nanoescala e experimentos.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>HSQ e-beam resist</td>
			<td>Dow Corning</td>
			<td>XR-1541-006</td>
			<td></td>
		</tr>
		<tr>
			<td>PMMA</td>
			<td>MicroChem</td>
			<td>950A2 M230002</td>
			<td></td>
		</tr>
		<tr>
			<td>Fast curing optical adhesive</td>
			<td>Norland Optical Adhesive</td>
			<td>NOA 81</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescent carboxyl microspheres</td>
			<td>Bangs Laboratories</td>
			<td>FC02F, FC03F</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescent carboxylate-modified microspheres</td>
			<td>Molecular Probes</td>
			<td>F-8888</td>
			<td></td>
		</tr>
		<tr>
			<td>Quartz slide</td>
			<td>SPI Supplies</td>
			<td>1020-AB</td>
			<td></td>
		</tr>
		<tr>
			<td>Inverted fluorescent microscope</td>
			<td>Nikon</td>
			<td>ECLIPSE TE2000-U</td>
			<td></td>
		</tr>
		<tr>
			<td>Nd:YAG laser</td>
			<td>Lightwave Electronics</td>
			<td>221-HD-V04</td>
			<td></td>
		</tr>
		<tr>
			<td>sCMOS camera</td>
			<td>PCO</td>
			<td>EDGE55</td>
			<td></td>
		</tr>
		<tr>
			<td>CCD camera</td>
			<td>Watec</td>
			<td>WAT-120N</td>
			<td></td>
		</tr>
		<tr>
			<td>Zero-order half-wave plate</td>
			<td>Thorlabs</td>
			<td>WPH05M-1064</td>
			<td></td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>Sigma-Aldrich</td>
			<td>T8787</td>
			<td></td>
		</tr>
		<tr>
			<td>Distilled water</td>
			<td>Invitrogen</td>
			<td>10977-023</td>
			<td></td>
		</tr>
		<tr>
			<td>Si Wafer</td>
			<td>Silicon Quest International</td>
			<td>708069</td>
			<td></td>
		</tr>
		<tr>
			<td>Optical lenses</td>
			<td>Thorlabs</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

fabrication and operation of a nano-optical conveyor belt

A técnica de utilização de feixes de laser focado para interceptar e exercem forças em pequenas partículas permitiu que muitas descobertas fundamentais nas ciências biológicas e físicas em nanoescala ao longo dos últimas décadas. Os progressos realizados neste domínio convida um estudo mais aprofundado dos sistemas ainda menores e em maior escala, com ferramentas que poderiam ser distribuídos com mais facilidade e fez mais amplamente disponível. Infelizmente, as leis fundamentais de difracção de limitar o tamanho mínimo do ponto focal de um feixe de laser, o que faz com que as partículas mais pequenas do que uma metade do comprimento de onda, em diâmetro difícil de armadilha e geralmente impede um operador de discriminar entre as partículas que estão mais próximos do que metade -Comprimento de onda. Isso impede a manipulação óptica de muitas nanopartículas estreitamente espaçados e limita a resolução de sistemas óptico-mecânicos. Além disso, utilizando feixes de manipulação óptica requer focalizados de formação de feixe ou de direcção, as quais podem ser muito volumoso e caro. Endereçarestas limitações na escalabilidade do sistema convencional de captura óptica nosso laboratório desenvolveu uma técnica alternativa que utiliza óptica de campo próximo para mover partículas através de um chip. Em vez de focar feixes de laser no campo distante, o campo próximo óptica de ressonadores plasmonic produz o reforço intensidade óptica local necessária para superar as restrições de difração e manipular partículas com maior resolução. Ressonadores de perto espaçadas produzir fortes armadilhas ópticas que podem ser abordados para mediar a mão-off de partículas a partir de um para o outro de uma forma-de tapetes transportadores semelhantes. Aqui, descrevemos como projetar e produzir uma correia transportadora com uma superfície de ouro modelado com plasmonic ressonadores em forma de C e como operá-lo com luz laser polarizada para atingir super-resolução manipulação de nanopartículas e transporte. O chip correia transportadora nano-óptico pode ser produzido usando técnicas de litografia e facilmente embalada e distribuída.

A Figura 7 é uma imagem do dispositivo final. No centro da superfície de ouro a 1 cm x 1 cm é a matriz de CSE e padrões de transporte, o que pode ser visto a partir de apenas uma vista angular. A Figura 6 é uma imagem de microscopia electrónica de varrimento de um exemplo de padrão de CSE no dispositivo final. O movimento de partículas de um poliestireno talão 390 nm viajar através de uma correia transportadora de nano-óptico de 5 um de compriment...

Watch this Scientific Journal Video about Fabrication and Operation of a Nano-Optical Conveyor Belt at JoVE.com

Fabrication and Operation of a Nano-Optical Conveyor Belt

The scalability and resolution of conventional optical manipulation techniques are limited by diffraction. We circumvent the diffraction limit and describe a method of optically transporting nanoparticles across a chip using a gold surface patterned with a path of closely spaced C-shaped plasmonic resonators.

Fabricação e operação de uma Correia Transportadora Nano-óptica

The technique of using focused laser beams to trap and exert forces on small particles has enabled many pivotal discoveries in the nanoscale biological ...

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11.5K visualizações.  Stanford University. The scalability and resolution of conventional optical manipulation techniques are limited by diffraction. We circumvent the diffraction limit and describe a method of optically transporting nanoparticles across a chip using a gold surface patterned with a path of closely spaced C-shaped plasmonic resonators.

Vídeo: Fabrication and Operation of a Nano-Optical Conveyor Belt

Fabrication, Densification, and Replica Molding of 3D Carbon Nanotube Microstructures

The introduction of new materials and processes to microfabrication has, in large part, enabled many important advances in microsystems, lab-on-a-chip devices, and their applications. In particular, capabilities for cost-effective fabrication of polymer microstructures were transformed by the advent of soft lithography and other micromolding techniques 1, 2, and this led a revolution in applications of microfabrication to biomedical engineering and biology. Nevertheless, it remains challenging to fabricate microstructures with well-defined nanoscale surface textures, and to fabricate arbitrary 3D shapes at the micro-scale. Robustness of master molds and maintenance of shape integrity is especially important to achieve high fidelity replication of complex structures and preserving their nanoscale surface texture. The combination of hierarchical textures, and heterogeneous shapes, is a profound challenge to existing microfabrication methods that largely rely upon top-down etching using fixed mask templates. On the other hand, the bottom-up synthesis of nanostructures such as nanotubes and nanowires can offer new capabilities to microfabrication, in particular by taking advantage of the collective self-organization of nanostructures, and local control of their growth behavior with respect to microfabricated patterns. 
Our goal is to introduce vertically aligned carbon nanotubes (CNTs), which we refer to as CNT "forests", as a new microfabrication material. We present details of a suite of related methods recently developed by our group: fabrication of CNT forest microstructures by thermal CVD from lithographically patterned catalyst thin films; self-directed elastocapillary densification of CNT microstructures; and replica molding of polymer microstructures using CNT composite master molds. In particular, our work shows that self-directed capillary densification ("capillary forming"), which is performed by condensation of a solvent onto the substrate with CNT microstructures, significantly increases the packing density of CNTs. This process enables directed transformation of vertical CNT microstructures into straight, inclined, and twisted shapes, which have robust mechanical properties exceeding those of typical microfabrication polymers. This in turn enables formation of nanocomposite CNT master molds by capillary-driven infiltration of polymers. The replica structures exhibit the anisotropic nanoscale texture of the aligned CNTs, and can have walls with sub-micron thickness and aspect ratios exceeding 50:1. Integration of CNT microstructures in fabrication offers further opportunity to exploit the electrical and thermal properties of CNTs, and diverse capabilities for chemical and biochemical functionalization 3.

We present methods for fabrication of patterned microstructures of vertically aligned carbon nanotubes (CNTs), and their use as master molds for production of polymer microstructures with organized nanoscale surface texture. The CNT forests are densified by condensation of solvent onto the substrate, which significantly increases their packing density and enables self-directed formation of 3D shapes.

Fabricação, Densificação e Replica Moldagem de Microestruturas de Nanotubos de Carbono 3D

The introduction of new materials and processes to microfabrication has, in large part, enabled many important advances in microsystems, lab-on-a-chip ...

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Synthesis and Operation of Fluorescent-core Microcavities for Refractometric Sensing

This paper discusses fluorescent core microcavity-based sensors that can operate in a microfluidic analysis setup. These structures are based on the formation of a fluorescent quantum-dot (QD) coating on the channel surface of a conventional microcapillary. Silicon QDs are especially attractive for this application, owing in part to their negligible toxicity compared to the II-VI and II-VI compound QDs, which are legislatively controlled substances in many countries. While the ensemble emission spectrum is broad and featureless, an Si-QD film on the channel wall of a capillary features a set of sharp, narrow peaks in the fluorescence spectrum, corresponding to the electromagnetic resonances for light trapped within the film. The peak wavelength of these resonances is sensitive to the external medium, thus permitting the device to function as a refractometric sensor in which the QDs never come into physical contact with the analyte. The experimental methods associated with the fabrication of the fluorescent-core microcapillaries are discussed in detail, as well as the analysis methods. Finally, a comparison is made between these structures and the more widely investigated liquid-core optical ring resonators, in terms of microfluidic sensing capabilities.

Fluorescent-core microcavity sensors employ a high-index quantum-dot coating in the channel of silica microcapillaries. Changes in the refractive index of fluids pumped into the capillary channel cause shifts in the microcavity fluorescence spectrum that can be used to analyze the channel medium.

Síntese e Operação de Fluorescente-core microcavidades de Sensoriamento refractométricos

This paper discusses  fluorescent core microcavity-based sensors that can operate in a microfluidic  analysis setup. These structures are based on the ...

Fabrication, Operation and Flow Visualization in Surface-acoustic-wave-driven Acoustic-counterflow Microfluidics

Surface acoustic waves (SAWs) can be used to drive liquids in portable microfluidic chips via the acoustic counterflow phenomenon. In this video we present the fabrication protocol for a multilayered SAW acoustic counterflow device. The device is fabricated starting from a lithium niobate (LN) substrate onto which two interdigital transducers (IDTs) and appropriate markers are patterned. A polydimethylsiloxane (PDMS) channel cast on an SU8 master mold is finally bonded on the patterned substrate. Following the fabrication procedure, we show the techniques that allow the characterization and operation of the acoustic counterflow device in order to pump fluids through the PDMS channel grid. We finally present the procedure to visualize liquid flow in the channels. The protocol is used to show on-chip fluid pumping under different flow regimes such as laminar flow and more complicated dynamics characterized by vortices and particle accumulation domains.

In this video we first describe fabrication and operation procedures of a surface acoustic wave (SAW) acoustic counterflow device. We then demonstrate an experimental setup that allows for both qualitative flow visualization and quantitative analysis of complex flows within the SAW pumping device.

Fabricação, Operação e Visualização de Fluxo em superfície acústico de ondas orientadas Microfluidics acústico contrafluxo

Surface acoustic waves (SAWs) can be used to drive liquids in portable microfluidic chips via the acoustic counterflow phenomenon. In this video we ...

Fabrication and Testing of Microfluidic Optomechanical Oscillators

Cavity optomechanics experiments that parametrically couple the phonon modes and photon modes have been investigated in various optical systems including microresonators. However, because of the increased acoustic radiative losses during direct liquid immersion of optomechanical devices, almost all published optomechanical experiments have been performed in solid phase. This paper discusses a recently introduced hollow microfluidic optomechanical resonator. Detailed methodology is provided to fabricate these ultra-high-Q microfluidic resonators, perform optomechanical testing, and measure radiation pressure-driven breathing mode and SBS-driven whispering gallery mode parametric vibrations. By confining liquids inside the capillary resonator, high mechanical- and optical- quality factors are simultaneously maintained.

Parametric optomechanical excitations have recently been experimentally demonstrated in microfluidic optomechanical resonators by means of optical radiation pressure and stimulated Brillouin scattering. This paper describes the fabrication of these microfluidic resonators along with methodologies for generating and verifying optomechanical oscillations.

Fabricação e Teste de microfluídicos optomechanical osciladores

Cavity optomechanics experiments that parametrically couple the phonon modes and photon modes have been investigated in various optical systems including ...

Fabrication Process of Silicone-based Dielectric Elastomer Actuators

This contribution demonstrates the fabrication process of dielectric elastomer transducers (DETs). DETs are stretchable capacitors consisting of an elastomeric dielectric membrane sandwiched between two compliant electrodes. The large actuation strains of these transducers when used as actuators (over 300% area strain) and their soft and compliant nature has been exploited for a wide range of applications, including electrically tunable optics, haptic feedback devices, wave-energy harvesting, deformable cell-culture devices, compliant grippers, and propulsion of a bio-inspired fish-like airship. In most cases, DETs are made with a commercial proprietary acrylic elastomer and with hand-applied electrodes of carbon powder or carbon grease. This combination leads to non-reproducible and slow actuators exhibiting viscoelastic creep and a short lifetime. We present here a complete process flow for the reproducible fabrication of DETs based on thin elastomeric silicone films, including casting of thin silicone membranes, membrane release and prestretching, patterning of robust compliant electrodes, assembly and testing. The membranes are cast on flexible polyethylene terephthalate (PET) substrates coated with a water-soluble sacrificial layer for ease of release. The electrodes consist of carbon black particles dispersed into a silicone matrix and patterned using a stamping technique, which leads to precisely-defined compliant electrodes that present a high adhesion to the dielectric membrane on which they are applied.

This manuscript shows the fabrication process for the manufacture of dielectric elastomer soft actuators based on silicone membranes. The three key stages of production are presented in detail: blade casting of thin silicone membranes; pad printing of compliant electrodes; and the assembly of all the components.

Processo de fabricação de base de silicone dielétricos Elastomer Atuadores

This contribution demonstrates the fabrication process of dielectric elastomer transducers (DETs). DETs are stretchable capacitors consisting of an ...

Fabrication and Operation of Acoustofluidic Devices Supporting Bulk Acoustic Standing Waves for Sheathless Focusing of Particles

Acoustophoresis refers to the displacement of suspended objects in response to directional forces from sound energy. Given that the suspended objects must be smaller than the incident wavelength of sound and the width of the fluidic channels are typically tens to hundreds of micrometers across, acoustofluidic devices typically use ultrasonic waves generated from a piezoelectric transducer pulsating at high frequencies (in the megahertz range). At characteristic frequencies that depend on the geometry of the device, it is possible to induce the formation of standing waves that can focus particles along desired fluidic streamlines within a bulk flow. Here, we describe a method for the fabrication of acoustophoretic devices from common materials and clean room equipment. We show representative results for the focusing of particles with positive or negative acoustic contrast factors, which move towards the pressure nodes or antinodes of the standing waves, respectively. These devices offer enormous practical utility for precisely positioning large numbers of microscopic entities (e.g., cells) in stationary or flowing fluids for applications ranging from cytometry to assembly.

Acoustofluidic devices use ultrasonic waves within microfluidic channels to manipulate, concentrate and isolate suspended micro and nanoscopic entities. This protocol describes the fabrication and operation of such a device supporting bulk acoustic standing waves to focus particles in a central streamline without the aid of sheath fluids.

Fabricação e operação de Acoustofluidic dispositivos que suportam a granel ondas acústicas pe para Sheathless Focando de Partículas

Acoustophoresis refers to the displacement of suspended objects in response to directional forces from sound energy. Given that the suspended objects must ...

Fabrication and Characterization of Superconducting Resonators

Superconducting microwave resonators are of interest for a wide range of applications, including for their use as microwave kinetic inductance detectors (MKIDs) for the detection of faint astrophysical signatures, as well as for quantum computing applications and materials characterization. In this paper, procedures are presented for the fabrication and characterization of thin-film superconducting microwave resonators. The fabrication methodology allows for the realization of superconducting transmission-line resonators with features on both sides of an atomically smooth single-crystal silicon dielectric. This work describes the procedure for the installation of resonator devices into a cryogenic microwave testbed and for cool-down below the superconducting transition temperature. The set-up of the cryogenic microwave testbed allows one to do careful measurements of the complex microwave transmission of these resonator devices, enabling the extraction of the properties of the superconducting lines and dielectric substrate (e.g., internal quality factors, loss and kinetic inductance fractions), which are important for device design and performance.

Superconducting microwave resonators are of interest for detection of light, quantum computing applications and materials characterization. This work presents a detailed procedure for fabrication and characterization of superconducting microwave resonator scattering parameters.

Fabricação e caracterização de supercondutores Resonators

Superconducting microwave resonators are of interest for a wide range of applications, including for their use as microwave kinetic inductance detectors ...

Solvent Bonding for Fabrication of PMMA and COP Microfluidic Devices

Thermoplastic microfluidic devices offer many advantages over those made from silicone elastomers, but bonding procedures must be developed for each thermoplastic of interest. Solvent bonding is a simple and versatile method that can be used to fabricate devices from a variety of plastics. An appropriate solvent is added between two device layers to be bonded, and heat and pressure are applied to the device to facilitate the bonding. By using an appropriate combination of solvent, plastic, heat, and pressure, the device can be sealed with a high quality bond, characterized as having high bond coverage, bond strength, optical clarity, durability over time, and low deformation or damage to microfeature geometry. We describe the procedure for bonding devices made from two popular thermoplastics, poly(methyl-methacrylate) (PMMA), and cyclo-olefin polymer (COP), as well as a variety of methods to characterize the quality of the resulting bonds, and strategies to troubleshoot low quality bonds. These methods can be used to develop new solvent bonding protocols for other plastic-solvent systems.

Solvent bonding is a simple and versatile method for fabricating thermoplastic microfluidic devices with high quality bonds. We describe a protocol to achieve strong, optically clear bonds in PMMA and COP microfluidic devices that preserve microfeature details, by a judicious combination of pressure, temperature, an appropriate solvent, and device geometry.

Bonding solvente para Fabricação de PMMA e COP microfluídicos

Thermoplastic microfluidic devices offer many advantages over those made from silicone elastomers, but bonding procedures must be developed for each ...

Construction and Operation of a Light-driven Gold Nanorod Rotary Motor System

The possibility to generate and measure rotation and torque at the nanoscale is of fundamental interest to the study and application of biological and artificial nanomotors and may provide new routes towards single cell analysis, studies of non-equilibrium thermodynamics, and mechanical actuation of nanoscale systems. A facile way to drive rotation is to use focused circularly polarized laser light in optical tweezers. Using this approach, metallic nanoparticles can be operated as highly efficient scattering-driven rotary motors spinning at unprecedented rotation frequencies in water.
In this protocol, we outline the construction and operation of circularly-polarized optical tweezers for nanoparticle rotation and describe the instrumentation needed for recording the Brownian dynamics and Rayleigh scattering of the trapped particle. The rotational motion and the scattering spectra provides independent information on the properties of the nanoparticle and its immediate environment. The experimental platform has proven useful as a nanoscopic gauge of viscosity and local temperature, for tracking morphological changes of nanorods and molecular coatings, and as a transducer and probe of photothermal and thermodynamic processes.

Plasmonic gold nanorods can be trapped in liquids and rotated at kHz frequencies using circularly-polarized optical tweezers. Introducing tools for Brownian dynamics analysis and light scatteringspectroscopy leads to a powerful system for research and application in numerous fields of science.

Construção e operação de um sistema de Motor controlado por luz ouro Nanorod Rotary

The possibility to generate and measure rotation and torque at the nanoscale is of fundamental interest to the study and application of biological and ...

Fabrication of Refractive-index-matched Devices for Biomedical Microfluidics

The use of microfluidic devices has emerged as a defining tool for biomedical applications. When combined with modern microscopy techniques, these devices can be implemented as part of a robust platform capable of making simultaneous complementary measurements. The primary challenge created by the combination of these two techniques is the mismatch in refractive index between the materials traditionally used to make microfluidic devices and the aqueous solutions typically used in biomedicine. This mismatch can create optical artifacts near the channel or device edges. One solution is to reduce the refractive index of the material used to fabricate the device by using a fluorinated polymer such as MY133-V2000 whose refractive index is similar to that of water (n = 1.33). Here, the construction of a microfluidic device made out of MY133-V2000 using soft lithography techniques is demonstrated, using O2 plasma in conjunction with an acrylic holder to increase the adhesion between the MY133-V2000 fabricated device and the polydimethylsiloxane (PDMS) substrate. The device is then tested by incubating it filled with cell culture media for 24 h to demonstrate the ability of the device to maintain cell culture conditions during the course of a typical imaging experiment. Finally, quantitative phase microscopy (QPM) is used to measure the distribution of mass within the live adherent cells in the microchannel. This way, the increased precision, enabled by fabricating the device from a low index of refraction polymer such as MY133-V2000 in lieu of traditional soft lithography materials such as PDMS, is demonstrated. Overall, this approach for fabricating microfluidic devices can be readily integrated into existing soft lithography workflows in order to reduce optical artifacts and increase measurement precision.

This protocol describes the fabrication of microfluidic devices from MY133-V2000 to eliminate artifacts that often arise in microchannels due to the mismatching refractive indices between microchannel structures and an aqueous solution. This protocol uses an acrylic holder to compress the encapsulated device, improving adhesion both chemically and mechanically.

Fabricação de dispositivos de refração-índice-combinada para microfluídica biomédica

The use of microfluidic devices has emerged as a defining tool for biomedical applications. When combined with modern microscopy techniques, these devices ...