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).

<ol>
	<li>Ashkin, A., Dziedzic, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+Trapping+and+Manipulation+Of+Viruses+and+Bacteria.">Optical Trapping and Manipulation Of Viruses and Bacteria.</a> Science. 235 (4795), 1517-1520 (1987).</li><li>Svoboda, K., Block, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biological+Applications+of+Optical+Forces.">Biological Applications of Optical Forces.</a> Annu. Rev. Biophys. Biomol. Struct. 23 (1), 247-285 (1994).</li><li>Neuman, K., Block, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+Trapping.">Optical Trapping.</a> Rev. Sci. Instrum. 75 (9), 2787-2809 (2004).</li><li>Fazal, F. M., Block, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+Tweezers+Study+Life+Under+Tension.">Optical Tweezers Study Life Under Tension.</a> Nat. Photonics. 5 (6), 318-321 (2011).</li><li>Bockelmann, U., Thomen, P., Essevaz-Roulet, B., Viasnoff, V., Heslot, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Unzipping+DNA+with+Optical+Tweezers:+High+Sequence+Sensitivity+and+Force+Flips.">Unzipping DNA with Optical Tweezers: High Sequence Sensitivity and Force Flips.</a> Biophys. J. 82 (3), 1537-1553 (2002).</li><li>Pang, Y., Gordon, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+Trapping+of+Single+Protein.">Optical Trapping of Single Protein.</a> Nano Lett. 12 (1), 402-406 (2012).</li><li>Dholakia, K., C&#780;izm&#780;ar&#769;, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shaping+the+Future+of+Manipulation.">Shaping the Future of Manipulation.</a> Nat. Photonics. 5 (6), 335-342 (2011).</li><li>Grier, D. G., Roichman, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Holographic+Optical+Trapping.">Holographic Optical Trapping.</a> Appl. Opt. 45 (5), 880-887 (2006).</li><li>Korda, P. T., Taylor, M. B., Grier, D. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kinetically+Locked-in+Colloidal+Transport+in+an+Array+of+Optical+Tweezers.">Kinetically Locked-in Colloidal Transport in an Array of Optical Tweezers.</a> Phys. Rev. Lett. 89 (12), 128301 (2002).</li><li>Pelton, M., Ladavac, K., Grier, D. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transport+and+Fractionation+in+Periodic+Potential-energy+Landscapes.">Transport and Fractionation in Periodic Potential-energy Landscapes.</a> Phys. Rev. E. 70 (3), 031108 (2004).</li><li>Eriksson, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Microfluidic+System+in+Combination+with+Optical+Tweezers+for+Analyzing+Rapid+and+Reversible+Cytological+Alterations+in+Single+Cells+upon+Environmental+Changes.">A Microfluidic System in Combination with Optical Tweezers for Analyzing Rapid and Reversible Cytological Alterations in Single Cells upon Environmental Changes.</a> Lab Chip. 7 (1), 71-76 (2007).</li><li>Applegate, R. W., Squier, J., Vestad, T., Oakey, J., Marr, D. W. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Optical Trapping, Manipulation, and Sorting of Cells and Colloids in Microfluidic Systems with Diode Laser. 12 (19), 4390-4398 (2004).</li><li>MacDonald, G. C., Spalding, G. C., Dholakia, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microfluidic+Sorting+in+an+Optical+Lattice.">Microfluidic Sorting in an Optical Lattice.</a> Nature. 426 (6965), 421-424 (2003).</li><li>Neale, S. L., MacDonald, M. P., Dholakia, K., Krauss, T. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=All-optical+Control+of+Microfluidic+Components+using+Form.">All-optical Control of Microfluidic Components using Form.</a> Nat. Mater. 4 (7), 530-533 (2005).</li><li>Juan, M. L., Righini, M., Quidant, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plasmon+Nano-optical+Tweezers.+.">Plasmon Nano-optical Tweezers. .</a> Nat. Photonics. 5 (6), 349-356 (2011).</li><li>Kwak, E. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+Trapping+with+Integrated+Near-Field+Apertures.">Optical Trapping with Integrated Near-Field Apertures.</a> J. Phys. Chem. B. 108 (36), 13607-13612 (2004).</li><li>Righini, M., Zelenina, A. S., Girard, C., Quidant, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Parallel+and+Selective+Trapping+in+a+Patterned+Plasmonic+Landscape.">Parallel and Selective Trapping in a Patterned Plasmonic Landscape.</a> Nat. Phys. 3 (7), 477-480 (2007).</li><li>Zhang, W., Huang, L., Santschi, C., Martin, O. J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Trapping+and+Sensing+10+nm+Metal+Nanoparticles+using+Plasmonic+Dipole+Antennas.">Trapping and Sensing 10 nm Metal Nanoparticles using Plasmonic Dipole Antennas.</a> Nano Lett. 10 (3), 1006-1011 (2010).</li><li>Wang, K., Schonbrun, E., Steinvurzel, P., Crozier, K. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Trapping+and+Rotating+Nanoparticles+using+a+Plasmonic+Nano-tweezer+with+an+Integrated+Heat+Sink.">Trapping and Rotating Nanoparticles using a Plasmonic Nano-tweezer with an Integrated Heat Sink.</a> Nat. Commun. 2, 469 (2011).</li><li>Shi, X., Hesselink, L., Thornton, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrahigh+Light+Trans-+mission+through+a+C-shaped+Nanoaperture.">Ultrahigh Light Trans- mission through a C-shaped Nanoaperture.</a> Opt. Lett. 28 (15), 1320-1322 (2003).</li><li>Chen, K., Lee, A., Hung, C., Huang, J., Yang, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transport+and+Trapping+in+Two-Dimensional+Nanoscale+Plasmonic+Optical+Lattice.">Transport and Trapping in Two-Dimensional Nanoscale Plasmonic Optical Lattice.</a> Nano Lett. 13, 4118-4122 (2013).</li><li>Cuche, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sorting+Nanoparticles+with+Intertwined+Plasmonic+and+Thermo-Hydrodynamical+Forces.">Sorting Nanoparticles with Intertwined Plasmonic and Thermo-Hydrodynamical Forces.</a> Nano Lett. 13, 4230-4235 (2013).</li><li>Hansen, P., Zheng, Y., Ryan, J., Hesselink, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nano-Optical+Conveyor+Belt,+Part+I:+Theory.">Nano-Optical Conveyor Belt, Part I: Theory.</a> Nano Lett. 14, 2965-2970 (2014).</li><li>Zheng, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nano-Optical+Conveyor+Belt,+Part+II:+Demonstration+of+Handoff+Between+Near-Field+Optical+Traps.">Nano-Optical Conveyor Belt, Part II: Demonstration of Handoff Between Near-Field Optical Traps.</a> Nano Lett. 14, 2971-2976 (2014).</li><li>Vogel, N., Zieleniecki, J., Koper, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=As+flat+as+it+gets:+Ultrasmooth+Surfaces+from+Template-stripping+Procedures.">As flat as it gets: Ultrasmooth Surfaces from Template-stripping Procedures.</a> Nanoscale. 4 (13), 3820-3832 (2012).</li><li>Zhu, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrafine+and+Smooth+Full+Metal+Nanostructures+for+Plasmonics.">Ultrafine and Smooth Full Metal Nanostructures for Plasmonics.</a> Adv. Mater. 22 (39), 4345-4349 (2010).</li><li>Kaleli, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electron+Beam+Lithography+of+HSQ+and+PMMA+Resists+and+Importance+of+their+Properties+to+Link+the+Nano+World+to+the+Micro+World.">Electron Beam Lithography of HSQ and PMMA Resists and Importance of their Properties to Link the Nano World to the Micro World.</a> , 105-108 (2010).</li></ol>

The authors have nothing to disclose.

Il NOCB combina le potenti forze di cattura e le piccole dimensioni trappola di approcci plasmoniche con la capacità di trasportare particelle, lungo disponibile solo per le tecniche convenzionali mirato a fascio. Unico al NOCB, le proprietà di cattura e di trasporto del sistema sono il risultato di patterning superficiale e non di modellare il fascio di illuminazione. Fornito l&#39;illuminazione è abbastanza luminoso e la sua polarizzazione o lunghezza d&#39;onda può essere modulata, particelle può essere tenuto o...

La cattura, l&#39;interrogatorio e la manipolazione di singole nanoparticelle sono di crescente importanza nel campo delle nanotecnologie. Pinzette ottiche sono diventati una tecnica di manipolazione particolarmente efficace per esperimenti di biologia molecolare 1-4, 5-7 e chimica nano-assemblaggio 7-10, dove sono abilitati esperimenti innovativi come la misura delle proprietà meccaniche di singole molecole di DNA 4 e l&#39;ordinamento delle cellule dalle loro proprietà ottiche 11,12. Scoperte su queste frontiere si aprono lo studio di sistemi ancora più piccoli, e fanno strada alla progettazione di nuovi prodotti e tecniche praticamente benefiche. A sua volta, questa tendenza spinge la necessità di nuove tecniche per manipolare piccole particelle, più rudimentali. Inoltre, vi è una spinta per costruire dispositivi &#39;lab-on-a-chip &quot;per eseguire queste funzioni più a buon mercato e in un pacchetto più piccolo per portare test chimici e biologici dallaboratorio e nel campo medico e per altri scopi 13,14. Purtroppo, intrappolamento ottico convenzionale (COT) non può soddisfare tutte le richieste crescenti di nanotecnologia. COT opera sul meccanismo di utilizzare un elevato apertura numerica (NA) lente obiettivo per portare la luce laser per un fuoco stretto, creando un picco localizzato in intensità ottica e alti gradienti di energia campo elettromagnetico. Questi gradienti di densità di energia esercitano una forza netta sul particelle di luce-dispersione che generalmente li attira verso il centro del fuoco. Intrappolando le particelle più piccole richiede potenza ottica superiore o una maggiore attenzione. Tuttavia, fasci di luce concentrato obbediscono al principio della diffrazione, che limita la dimensione minima della macchia focale e pone un limite superiore al gradiente di densità di energia. Questo ha due conseguenze immediate: COT non può trattenere piccoli oggetti in modo efficiente, e COT ha difficoltà a discriminare tra particelle ravvicinati, risoluzione di catturalimitazione nota come problema le &quot;dita grasse. Inoltre, l&#39;implementazione multipla cattura particella con COT richiede sistemi di ottica fascio sterzanti o modulatori di luce spaziali, componenti che aumentano drasticamente il costo e la complessità di un sistema di intrappolamento ottico. Un modo per aggirare le limitazioni fondamentali convenzionali fasci focalizzati di luce, detto propagare nel campo lontano, è quello di sfruttare invece i gradienti di energia elettromagnetica ottica nel campo vicino. Il campo vicino decade esponenzialmente lontano da fonti di campi elettromagnetici, il che significa che non solo è altamente localizzata a queste fonti, ma espone anche molto elevati gradienti nella sua densità di energia. I vicini campi di risonatori nano-metallici, quali aperture bowtie, pilastri nano, e incisioni a forma di C, hanno dimostrato di esporre straordinarie concentrazioni di energia elettromagnetica, ulteriormente rafforzata dall&#39;azione plasmonica di oro e argento a quasi infrle lunghezze d&#39;onda ARED e ottici. Questi risonatori sono stati utilizzati per intrappolare particelle estremamente piccole ad alta efficienza e la risoluzione 15-22. Sebbene questa tecnica si è dimostrata efficace in grado di intrappolare piccole particelle, ma ha anche dimostrato di essere limitato nella sua capacità di trasportare particelle range sensibile, che è necessaria se i sistemi in campo vicino sono di interfacciarsi con sistemi di campo lontano o microfluidica. Recentemente, il nostro gruppo ha proposto una soluzione a questo problema. Quando risonatori sono posizionati molto vicini tra loro, una particella può in linea di principio migrare da un campo vicino trappola ottica all&#39;altro senza essere rilasciato dalla superficie. La direzione di trasporto può essere determinato se trappole adiacenti possono essere accesi e spenti separatamente. Un array lineare di tre o più risonatori indirizzabili, in cui ciascun risonatore è sensibile ad una polarizzazione o lunghezza d&#39;onda di luce differente da quella dei suoi vicini, funziona come un nastro trasportatore ottica, trasportando nanopartiCicli su una distanza di alcuni micron su un chip. Il cosiddetto &#39;Nano-ottica Nastro trasportatore&#39; (NOCB) è unico tra i regimi risonatore di cattura plasmoniche, in quanto non solo può contenere particelle in luogo, ma può anche spostarli ad alta velocità lungo le piste fantasia, raccogliere o disperdere le particelle, mescolare e coda, e persino dalle proprietà ordinarli come la mobilità 23. Tutte queste funzioni sono controllate modulando la polarizzazione o lunghezza d&#39;onda di illuminazione, senza necessità per l&#39;ottica del fascio sterzanti. Come trappola ottica in campo vicino, il NOCB intrappolando risoluzione è superiore a quella dei tradizionali focalizzato travi trappole ottiche, in modo che possa distinguere tra particelle in prossimità; perché utilizza una nanostruttura metallica per concentrare la luce in una cattura bene, è a basso consumo, e non richiede componenti ottici costosi come obiettivo elevata NA. Inoltre, molti NOCBs possono funzionare in parallelo, ad alta den imballaggiosity, sullo stesso substrato, e 1 W di potenza può guidare più di 1200 aperture 23. Abbiamo recentemente dimostrato la prima NOCB polarizzazione-driven, senza intoppi spingendo una nanoparticella avanti e indietro lungo un 4,5 micron pista 24. In questo articolo vi presentiamo le misure necessarie per progettare e fabbricare il dispositivo, otticamente attivarlo e riproduciamo l&#39;esperimento di trasporto. Speriamo che rendendo questa tecnica più ampiamente disponibile contribuirà a colmare il divario tra le dimensioni ottica microfluidica, in campo lontano, e dispositivi in ​​nanoscala e sperimentazioni.

<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

La tecnica di utilizzare raggi laser mirati per intrappolare e esercitare forze in piccole particelle ha permesso a molte scoperte cardine nelle scienze biologiche e fisiche nanoscala nel corso degli ultimi decenni. I progressi compiuti in questo campo invita ulteriore studio di sistemi ancora più piccoli e ad una scala più ampia, con strumenti che potrebbero essere distribuiti più facilmente e reso più ampiamente disponibile. Purtroppo, le leggi fondamentali della diffrazione limitano la dimensione minima del punto focale di un fascio laser, il che rende le particelle più piccole di una mezza lunghezza d&#39;onda di diametro difficile da intrappolare e generalmente impedisce all&#39;operatore di discriminare tra le particelle che sono più vicini della metà -wavelength. Ciò preclude la manipolazione ottica di molte nanoparticelle ravvicinati e limita la risoluzione di sistemi ottici-meccanici. Inoltre, la manipolazione mediante fasci focalizzati richiede ottica beam-forming e di sterzo, che possono essere molto ingombranti e costosi. Indirizzarequeste limitazioni nella scalabilità del sistema di intrappolamento ottico convenzionale nostro laboratorio ha messo a punto una tecnica alternativa che utilizza l&#39;ottica di campo vicino per spostare particelle attraverso un chip. Invece di concentrarsi raggi laser nel campo lontano, il vicino campo ottico di risonatori plasmoniche produce la necessaria valorizzazione locale intensità ottica per superare le restrizioni di diffrazione e manipolare particelle a più alta risoluzione. Risonatori ravvicinate producono forti trappole ottiche che possono essere indirizzati a mediare l&#39;hand-off di particelle da una all&#39;altra in un modo nastro trasportatore-like. Qui, descriviamo come progettare e produrre un nastro trasportatore con una superficie d&#39;oro fantasia con plasmoniche risonatori a forma di C e come farlo funzionare con luce laser polarizzata per ottenere super-risoluzione manipolazione delle nanoparticelle e dei trasporti. Il convogliatore trucioli cinghia nano-ottica può essere prodotto con tecniche di litografia e facilmente confezionato e distribuito.

La figura 7 è una foto del dispositivo finale. Al centro della superficie d&#39;oro 1 cm x 1 cm è la matrice di CSE e trasportatori modelli che possono essere poco visibili guardando un angolo vista. Figura 6 è una immagine al microscopio elettronico a scansione di una sequenza di esempio CSE sul dispositivo finale. Il movimento delle particelle di 390 nm in polistirolo viaggia attraverso un nastro trasportatore nano-ottica 5 micron di lunghezza ?...

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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.

Fabbricazione e funzionamento di un nano-ottica Nastro trasportatore

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 Views.  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.

Video: 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.

Molding Fabrication, densificazione e Replica di microstrutture 3D Nanotubi di carbonio

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.

Sintesi e funzionamento del fluorescente-core microcavità per il Rilevamento rifrattometrico

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.

Fabbricazione, il funzionamento e la visualizzazione del flusso in superficiali acustiche onda-driven Microfluidics Acoustic-controcorrente

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.

Fabbricazione e la sperimentazione di microfluidici optomechanical Oscillatori

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.

Fabbricazione Processo di base di silicone elastomero dielettrici Attuatori

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.

Realizzazione e di funzionamento dei dispositivi che supportano Acoustofluidic Bulk onde acustiche piedi per guaina di messa a fuoco di particelle

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.

Fabbricazione e caratterizzazione di superconduttori risonatori

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 per la fabbricazione di PMMA e COP dispositivi microfluidici

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.

Costruzione e funzionamento di un sistema motore basato su luce oro 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.

Fabbricazione di dispositivi rifrangenti-Indice-abbinati per biomedica microfluidica

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