Nous remercions la Fondation Lindback pour un soutien financier, et le Dr Alexander Sidorenko et Elza Chu pour des discussions fructueuses et une assistance technique, et le professeur Robert Smith pour son aide avec le C dosages elegans.

NOTE: Dans les procédures décrites ci-dessous, les consignes de sécurité de laboratoire doivent toujours être respectées. Il est particulièrement important de la sécurité lorsqu&#39;ils traitent avec haute tension (&gt; 500 V) et manipulation de produits chimiques. 1. revêtement d&#39;un substrat conducteur avec la suie de bougie <ol><li> Cut cuivre métal en rectangles (75 x 43 mm, 0,5 mm d&#39;épaisseur). Nettoyez chaque substrat de cuivre par immersion dans de gravure de cuivre pour environ 30 secondes, laver avec de l&#39;eau du robinet pendant environ 20 secondes, et sécher sur papier. NOTE: Si vous utilisez la méthode 1 ci-dessous, changer les dimensions de 75 x 25 mm à insérer dans la machine. </li><li> Balayer une bougie de paraffine allumé sous le substrat de cuivre pendant 30-45 secondes, pour obtenir un revêtement de suie à peu près uniforme (environ 40 um d&#39;épaisseur). Gardez le substrat à ~ 1 cm à l&#39;intérieur de la flamme. Ne touchez pas la surface de la suie fragile. </li></ol> 2. Protéger la couche de suie avec revêtement NOTE: La couche de suie est très fragile, Et doit être recouvert d&#39;une protection. Deux alternatives simples (méthodes 1 et 2 ci-dessous) sont proposées ici, mais les protocoles plus robustes sont actuellement en cours de développement. <ol><li> Méthode 1 <ol><li> Charger l&#39;échantillon dans l&#39;évaporateur de métal ou d&#39;un système de pulvérisation cathodique. En suivant les procédures de fonctionnement du système, évacuer la chambre, et commencer dépôt contrôlé de l&#39;or sur la couche de suie (150-200 nm). Laissez l&#39;appareil refroidir à la température ambiante. </li><li> Dip-couche métallisée du substrat dans une solution de 1-dodécanethiol (1% v / v dans l&#39;éthanol à 95%, ACS / qualité USP), pendant 10 minutes dans une hotte chimique. Ensuite, en tenant l&#39;appareil à un angle proche de 60 °, laver délicatement la surface avec plusieurs gouttes d&#39;éthanol seulement. Que les dispositifs sec, du jour au lendemain. </li></ol></li><li> Méthode 2 <ol><li> Dans une hotte chimique, immédiatement après le revêtement du substrat avec de la suie et alors que le substrat est encore chaude de la flamme de la bougie, déposer des gouttelettes de liquide fluoré sur un côté de lasubstrat, et incliner le substrat à un angle proche de 90 °. Déposez plusieurs gouttelettes, et laissez-les rouler sur la surface de la suie entier. NOTE: Lorsque la gouttelette tombe sur un point, la suie sera emporté de cette région. Que les gouttelettes de liquide fluoré propagation le plus possible. </li><li> Cuire le substrat sur une plaque chauffante (160 ° C pendant 15 min) à l&#39;intérieur d&#39;une hotte chimique. </li><li> Laissez le substrat reposer toute la nuit à la température ambiante avant de l&#39;utiliser. Stocker indéfiniment. </li></ol></li></ol> 3. Fabrication de électrodes supérieures (Adapté de Abdelgawad et al. 12) <ol><li> Dessiner les électrodes à l&#39;aide de logiciels de conception graphique. Chaque électrode est de 2 mm de long, 0,3 mm de largeur, et l&#39;écart entre les électrodes est de 0,3 mm. L&#39;écart entre contacts (à enclencher dans le connecteur, voir ci-dessous) est de 2,3 mm (figure 1). </li><li> Coupez un stratifié de cuivre souple (35 um d&#39;épaisseur) dans le format Monarch (3,87 x 7,5 pouces). Utiliser d&#39;autres tailles if compatible avec l&#39;imprimante. Chargez le stratifié dans le bac d&#39;alimentation manuelle d&#39;une imprimante couleur. </li><li> Assurez-vous d&#39;utiliser &quot;noir riche&quot;, ou &quot;inscription noire&quot;, lors de l&#39;impression sur la feuille de cuivre (voir Abdelgawad et al. 12 pour plus de détails) afin de permettre une couche plus dense de l&#39;encre noire sur le substrat de cuivre, de protéger le motif imprimé lors de la gravure . Laissez le substrat sèche complètement imprimé, du jour au lendemain. </li><li> A l&#39;intérieur d&#39;une hotte chimique, réchauffer (40 ° C) avec un bécher de 50 ml de solution d&#39;attaque du cuivre. Trempez le stratifié imprimé dans le bécher, et secouez-la délicatement dans la solution pendant environ 10 min. Gravure temps dépend de la solution de gravure de cuivre. Toutes les quelques minutes, vérifier la corrosion et voir si le motif est intact. </li><li> Laver soigneusement le stratifié avec de l&#39;eau, et enlever le revêtement avec de l&#39;acétone et de l&#39;éthanol dans la hotte chimique. Laver une fois de plus, et doucement sécher le stratifié avec une serviette en papier. </li><li> Fixez avec précaution le stratifié avec des électrodes à un gladiapositive ss (75 x 25 mm, ~ 1 mm d&#39;épaisseur), en utilisant du ruban adhésif double face. Éviter les poches d&#39;air. </li><li> Fixer un film de perfluoroalkoxy PFA pour les électrodes à l&#39;aide de ruban adhésif. Cela sert à éviter tout contact accidentel des électrodes avec la goutte, ce qui endommage les électrodes supérieures en raison de court-circuit. </li></ol> 4. L&#39;interface électronique (circuit de la figure 2) <ol><li> Souder les relais et les condensateurs C à une carte de circuit universel. </li><li> Assemblez le reste des 10 pilotes relais sur une planche à pain sans soudure pour circuits électroniques. </li><li> Fil d&#39;entrée de chaque conducteur de relais à un canal dans le panneau de contrôle. </li><li> Casser délicatement les électrodes supérieures dans un connecteur (Figure 3). Fil de sortie de chaque commande de relais à une électrode supérieure, comme représenté sur la figure. Notez qu&#39;il ya un contact du connecteur à la terre entre une paire de fils de relais, pour réduire le bruit électrique. REMARQUE: Le connecteur se trouve sur une plate-forme réglable pour contrôler til distance (0,1-0,5 mm) entre le substrat (suie-plaqué) haut et en bas. </li><li> Utilisez un programme pour contrôler le calendrier pour haute tension (HT) application (environ 0,8 sec) pour 4 électrodes en même temps, en déplaçant une électrode dans la direction du mouvement (par exemple, pour 0.8 sec, actionner 1234, puis 2345, 3456, etc. ., 0,8 sec pour chaque groupe, puis vers l&#39;arrière, se déplace de façon gouttelettes dans la direction opposée aussi bien). </li></ol> 5. Visualisation des gouttelettes et la manipulation <ol><li> Pour enregistrer le mouvement des gouttelettes, en utilisant le système de visualisation, qui est composé d&#39;un 24X - Ensemble de grossissement 96X associé à une caméra CCD. Connectez le magnétoscope à la caméra en utilisant S-vidéo. </li><li> Introduire à la pipette une goutte 4 pl contenant C. elegans dans un milieu sur le fond du substrat revêtu de la suie. </li><li> Apportez les électrodes supérieures à ~ 0,3 mm au-dessus de la gouttelette. La goutte doit être proche de la moyenne, juste en dessous de la cinquième électrode, pour faciliter l&#39;opération. </li><li> Tournez sur l&#39;interface électronique et haute tension (500 V RMS), et régler la distance d&#39;électrode supérieure de la gouttelette jusqu&#39;à ce qu&#39;il commence à se déplacer. Ne laissez pas les électrodes supérieures touchent la gouttelette. </li><li> Recueillir des données en enregistrant le nombre de transferts de gouttelettes de succès sur le dispositif en réponse à des impulsions électriques. Un essai réussi est caractérisé par au moins 700 transferts de gouttelettes, soit un transfert après chaque impulsion électrique. </li><li> Recueillir des données en continu, jusqu&#39;à ce que la goutte ne bouge pas en réponse à 5 à 10 impulsions. NOTE: Lorsque la surface commence à se dégrader, le mouvement pourrait être rétablie en mettant les électrodes supérieures proche de la gouttelette. </li></ol>

<ol>
	<li>Fair, R. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Digital+microfluidics:+is+a+true+lab-on-a-chip+possible.">Digital microfluidics: is a true lab-on-a-chip possible.</a> Microfluid Nanofluid. 3 (3), 245-281 (2007).</li><li>Gupta, S., Alargova, R. G., Kilpatrick, P. K., Velev, O. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On-Chip+Dielectrophoretic+Coassembly+of+Live+Cells+and+Particles+into+Responsive+Biomaterials.">On-Chip Dielectrophoretic Coassembly of Live Cells and Particles into Responsive Biomaterials.</a> Langmuir. 26 (5), 3441-3452 (2009).</li><li>Shih, S. C., 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=Dried+blood+spot+analysis+by+digital+microfluidics+coupled+to+nanoelectrospray+ionization+mass+spectrometry.">Dried blood spot analysis by digital microfluidics coupled to nanoelectrospray ionization mass spectrometry.</a> Anal Chem. 84 (8), 3731-3738 (2012).</li><li>Gorbatsova, J., Borissova, M., Kaljurand, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrowetting-on-dielectric+actuation+of+droplets+with+capillary+electrophoretic+zones+for+off-line+mass+spectrometric+analysis.">Electrowetting-on-dielectric actuation of droplets with capillary electrophoretic zones for off-line mass spectrometric analysis.</a> J Chromatogr. 1234, 9-15 (2012).</li><li>Qin, J., Wheeler, A. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Maze+exploration+and+learning+in+C.+elegans.">Maze exploration and learning in C. elegans.</a> Lab Chip. 7 (2), 186-192 (2007).</li><li>Koc, Y., de Mello, A. J., McHale, G., Newton, M. I., Roach, P., Shirtcliffe, N. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nano-scale+superhydrophobicity:+suppression+of+protein+adsorption+and+promotion+of+flow-induced+detachment.">Nano-scale superhydrophobicity: suppression of protein adsorption and promotion of flow-induced detachment.</a> Lab Chip. 8 (4), 582-586 (2008).</li><li>Perry, G., Thomy, V., Das, M. 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The authors declare that they have no competing financial interests.

L&#39;étape la plus critique de ce protocole est la protection de la couche de suie, directement associée à la réussite dans les gouttelettes en mouvement. Métallisation de la couche de suie (méthode 1 ci-dessus) permet à près de 100% de réussite de la fabrication. Toutefois, la durée de fonctionnement maximale est d&#39;environ 10 min; éventuellement, les fractions sont gouttelettes mouillent la suie à travers des trous dans la couche de métal. Le revêtement de la couche de suie avec le liquide fluoré es...

La miniaturisation des dispositifs qui fonctionnent avec des liquides est d&#39;une importance primordiale pour le développement de plates-formes &quot;lab-on-a-chip». En ce sens, les deux dernières décennies ont vu un progrès significatif dans le domaine de la microfluidique, avec une variété d&#39;applications. 1-5 Contrastant avec le transport de fluide dans les canaux fermés (canal microfluidique), DMF manipule gouttelettes sur des réseaux d&#39;électrodes. L&#39;un des mérites les plus attrayants de cette technique est l&#39;absence de pièces mobiles pour le transport de fluides, et le mouvement est immédiatement arrêté en désactivant signaux électriques. Cependant, le mouvement des gouttelettes dépend contenu de gouttelettes, certainement une caractéristique indésirable pour une plate-forme universelle &quot;lab-on-a-chip». Gouttelettes contenant des protéines et d&#39;autres analytes collent aux surfaces de l&#39;appareil, devenir immobile. Sans doute, cela a été la principale limitation pour élargir le champ des applications DMF; 6-8alternatives pour minimiser l&#39;encrassement de la surface indésirable impliquent l&#39;ajout d&#39;espèces chimiques supplémentaires à la goutte ou ses environs, ce qui pourrait avoir une incidence sur le contenu de gouttelettes. Auparavant, notre groupe a développé un dispositif pour permettre le transport des cellules et des protéines dans le DMF, sans additifs supplémentaires (appareils de terrain-DW). 9 Ceci a été réalisé en combinant une surface basé sur la suie de bougie, 10 avec une géométrie du dispositif qui favorise gouttelettes de roulement et conduit à une force ascendante sur la gouttelette, ce qui réduit davantage l&#39;interaction des gouttelettes de la surface. Dans cette approche, le mouvement des gouttelettes est pas associé à un mouillage de la surface 11. Le but de la méthode détaillée décrit ci-dessous est de réaliser un dispositif de DMF capable de transporter des gouttelettes contenant des protéines, des cellules et des organismes entiers, sans additifs supplémentaires. Les appareils de terrain-DW ouvrent la voie à des plates-formes entièrement contrôlées de travail en grande partie indépendamment de gouttelettes chimistery. Ici, nous avons également présentes simulations montrent que, malgré la haute tension nécessaire au fonctionnement du dispositif, la chute de tension aux bornes de la gouttelette est d&#39;une petite fraction de la tension appliquée, ce qui indique des effets négligeables sur l&#39;intérieur de la gouttelette bioanalytes. En fait, des essais préliminaires avec Caenorhabditis elegans (C. elegans), un nématode utilisé pour une variété d&#39;études de la biologie, qui montrent vers nage normale que des tensions sont appliquées.

<table border="0" cellpadding="0" cellspacing="0" width="1230">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:231px;">Name of Material/ Equipment</td>
			<td style="width:119px;">Company</td>
			<td style="width:161px;">Catalog Number</td>
			<td style="width:720px;">Comments/Description</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:231px;">Paraffin candle</td>
			<td style="width:119px;"></td>
			<td style="width:161px;"></td>
			<td>Any paraffin candle</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:231px;">Sputtering system</td>
			<td style="width:119px;">Denton Vacuum, Moorestown, NJ</td>
			<td style="width:161px;"></td>
			<td>Sputter coater Desk V HP equipped with an Au target.&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:231px;">1-dodecanethiol</td>
			<td style="width:119px;">Sigma-Aldrich</td>
			<td align="right" style="width:161px;">471364</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:231px;">Teflon</td>
			<td style="width:119px;">Dupont</td>
			<td style="width:161px;">AF-1600</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:231px;">Fluorinert FC-40</td>
			<td style="width:119px;">Sigma-Aldrich</td>
			<td style="width:161px;">F9755</td>
			<td>Fluorinated liquid: Prepare Teflon-AF resin in Fluorinert FC-40, 1:100 (w/w), to create the hydrophobic coating.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:231px;">Graphic design software -Adobe Illustrator</td>
			<td style="width:119px;">Adobe Systems</td>
			<td style="width:161px;"></td>
			<td>Other softwares might be used as well.</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:18px;width:231px;">Copper laminate</td>
			<td style="width:119px;">Dupont</td>
			<td style="width:161px;">LF9110</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:231px;">Laser Printer</td>
			<td style="width:119px;">Xerox</td>
			<td style="width:161px;">Phaser 6360 or similar</td>
			<td>Check for the compatibility with &#34;rich black&#34; or &#34;registration black&#34; (see text).</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:231px;">Copper Etchant</td>
			<td style="width:119px;">Transene</td>
			<td style="width:161px;">CE-100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:231px;">Perfluoroalkoxy (PFA) film</td>
			<td style="width:119px;">McMaster-Carr</td>
			<td style="width:161px;">84955K22</td>
			<td></td>
		</tr>
		<tr height="28">
			<td height="28" style="height:28px;width:231px;">Breadboard</td>
			<td style="width:119px;">Allied Electronics</td>
			<td style="width:161px;">70012450 or similar</td>
			<td>Large enough to allow the assemble of 10 drivers.</td>
		</tr>
		<tr height="28">
			<td height="28" style="height:28px;width:231px;">Universal circuit board</td>
			<td style="width:119px;">Allied Electronics</td>
			<td style="width:161px;">70219535 or similar</td>
			<td></td>
		</tr>
		<tr height="28">
			<td height="28" style="height:28px;width:231px;">Connector</td>
			<td style="width:119px;">Allied Electronics</td>
			<td style="width:161px;">5145154-8 or similar</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:231px;">Control board and control program (LabView software)</td>
			<td style="width:119px;">National Instruments</td>
			<td style="width:161px;">NI-6229 or similar</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:231px;">High-voltage amplifier</td>
			<td style="width:119px;">Trek</td>
			<td style="width:161px;">PZD700</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:231px;">Resistor R 27 k&#8486;, 1/4 W</td>
			<td style="width:119px;">Allied&#160;</td>
			<td align="right" style="width:161px;">2964762</td>
			<td></td>
		</tr>
		<tr height="27">
			<td height="27" style="height:27px;width:231px;">Capacitors C and C1, 100 nF, 60 V</td>
			<td style="width:119px;">Allied&#160;</td>
			<td align="right" style="width:161px;">8817183</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:231px;">Transistor T, NPN</td>
			<td style="width:119px;">Allied&#160;</td>
			<td align="right" style="width:161px;">9350289</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:231px;">Diode D, 1N4007</td>
			<td style="width:119px;">Allied&#160;</td>
			<td align="right" style="width:161px;">2660007</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:231px;">Relay&#160;</td>
			<td style="width:119px;">Allied&#160;</td>
			<td align="right" style="width:161px;">8862527</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:231px;">Visualization system</td>
			<td style="width:119px;">Edmund Optics</td>
			<td style="width:161px;">VZM 200i or similar</td>
			<td>System magnification 24X- 96X. It is combined with a Hitachi KP-D20B 1/2 in CCD Color Camera.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:231px;">Recorder</td>
			<td style="width:119px;">Sony</td>
			<td style="width:161px;">GV-D1000 NTSC or similar</td>
			<td>It is connected to the camera by an S-video cable.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:231px;">Simulations</td>
			<td style="width:119px;">COMSOL Multiphysics</td>
			<td style="width:161px;">V. 4.4</td>
			<td></td>
		</tr>
	</tbody>
</table>

taking advantage of reduced droplet-surface interaction to optimize transport of bioanalytes in digital microfluidics

Digital microfluidics (DMF), a technique for manipulation of droplets, is a promising alternative for the development of &#8220;lab-on-a-chip&#8221; platforms. Often, droplet motion relies on the wetting of a surface, directly associated with the application of an electric field; surface interactions, however, make motion dependent on droplet contents, limiting the breadth of applications of the technique.
Some alternatives have been presented to minimize this dependence. However, they rely on the addition of extra chemical species to the droplet or its surroundings, which could potentially interact with droplet moieties. Addressing this challenge, our group recently developed Field-DW devices to allow the transport of cells and proteins in DMF, without extra additives.
Here, the protocol for device fabrication and operation is provided, including the electronic interface for motion control. We also continue the studies with the devices, showing that multicellular, relatively large, model organisms can also be transported, arguably unaffected by the electric fields required for device operation.

Auparavant, nous avons utilisé les appareils de terrain-DW pour permettre le mouvement des protéines dans le DMF. En particulier, les gouttelettes avec de l&#39;albumine de sérum bovin (BSA) peuvent être déplacés à une concentration 2000 fois plus élevée que celle rapportée précédemment par d&#39;autres auteurs (sans additifs). Cela était dû à l&#39;interaction réduite entre gouttelettes et surface; La figure 4 montre une gouttelette contenant étiquetées par fluorescence BSA (voir Frei...

Watch this Scientific Journal Video about Taking Advantage of Reduced Droplet-surface Interaction to Optimize Transport of Bioanalytes in Digital Microfluidics at JoVE.com

Taking Advantage of Reduced Droplet-surface Interaction to Optimize Transport of Bioanalytes in Digital Microfluidics

The protocol for fabrication and operation of field dewetting devices (Field-DW) is described, as well as the preliminary studies of the effects of electric fields on droplet contents.

Profitant de interaction réduite des gouttelettes de la surface pour optimiser le transport de Bioanalytes en microfluidique digitale

Digital microfluidics (DMF), a technique for manipulation of droplets, is a promising alternative for the development of &#8220;lab-on-a-chip&#8221; ...

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7.8K vues.  University of the Sciences. The protocol for fabrication and operation of field dewetting devices (Field-DW) is described, as well as the preliminary studies of the effects of electric fields on droplet contents.

Vidéo: Taking Advantage of Reduced Droplet-surface Interaction to Optimize Transport of Bioanalytes in Digital Microfluidics

Evaluating Plasmonic Transport in Current-carrying Silver Nanowires

Plasmonics is an emerging technology capable of simultaneously transporting a plasmonic signal and an electronic signal on the same information support1,2,3. In this context, metal nanowires are especially desirable for realizing dense routing networks4. A prerequisite to operate such shared nanowire-based platform relies on our ability to electrically contact individual metal nanowires and efficiently excite surface plasmon polaritons5 in this information support. In this article, we describe a protocol to bring electrical terminals to chemically-synthesized silver nanowires6 randomly distributed on a glass substrate7. The positions of the nanowire ends with respect to predefined landmarks are precisely located using standard optical transmission microscopy before encapsulation in an electron-sensitive resist. Trenches representing the electrode layout are subsequently designed by electron-beam lithography. Metal electrodes are then fabricated by thermally evaporating a Cr/Au layer followed by a chemical lift-off. The contacted silver nanowires are finally transferred to a leakage radiation microscope for surface plasmon excitation and characterization8,9. Surface plasmons are launched in the nanowires by focusing a near infrared laser beam on a diffraction-limited spot overlapping one nanowire extremity5,9. For sufficiently large nanowires, the surface plasmon mode leaks into the glass substrate9,10. This leakage radiation is readily detected, imaged, and analyzed in the different conjugate planes in leakage radiation microscopy9,11. The electrical terminals do not affect the plasmon propagation. However, a current-induced morphological deterioration of the nanowire drastically degrades the flow of surface plasmons. The combination of surface plasmon leakage radiation microscopy with a simultaneous analysis of the nanowire electrical transport characteristics reveals the intrinsic limitations of such plasmonic circuitry.

Silver nanowires can simultaneously transport electrons and optical information in the form of surface plasmons. A procedure is described here to realize such a shared circuitry and the limitations at propagating both information carriers are evaluated.

Plasmonics is an emerging technology capable of simultaneously transporting a plasmonic signal and an electronic signal on the same information ...

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Characterization of Thermal Transport in One-dimensional Solid Materials

The TET (transient electro-thermal) technique is an effective approach developed to measure the thermal diffusivity of solid materials, including conductive, semi-conductive or nonconductive one-dimensional structures. This technique broadens the measurement scope of materials (conductive and nonconductive) and improves the accuracy and stability. If the sample (especially biomaterials, such as human head hair, spider silk, and silkworm silk) is not conductive, it will be coated with a gold layer to make it electronically conductive. The effect of parasitic conduction and radiative losses on the thermal diffusivity can be subtracted during data processing. Then the real thermal conductivity can be calculated with the given value of volume-based specific heat (&#961;cp), which can be obtained from calibration, noncontact photo-thermal technique or measuring the density and specific heat separately. In this work, human head hair samples are used to show how to set up the experiment, process the experimental data, and subtract the effect of parasitic conduction and radiative losses.

The TET (transient electro-thermal) technique is an effective approach developed to measure the thermal diffusivity of solid materials.

Caractérisation des Transports thermique dans des matériaux solides unidimensionnels

The TET (transient electro-thermal) technique is an effective approach developed to measure the thermal diffusivity of solid materials, including ...

Real-Time DC-dynamic Biasing Method for Switching Time Improvement in Severely Underdamped Fringing-field Electrostatic MEMS Actuators

Mechanically underdamped electrostatic fringing-field MEMS actuators are well known for their fast switching operation in response to a unit step input bias voltage. However, the tradeoff for the improved switching performance is a relatively long settling time to reach each gap height in response to various applied voltages. Transient applied bias waveforms are employed to facilitate reduced switching times for electrostatic fringing-field MEMS actuators with high mechanical quality factors. Removing the underlying substrate of the fringing-field actuator creates the low mechanical damping environment necessary to effectively test the concept. The removal of the underlying substrate also a has substantial improvement on the reliability performance of the device in regards to failure due to stiction. Although DC-dynamic biasing is useful in improving settling time, the required slew rates for typical MEMS devices may place aggressive requirements on the charge pumps for fully-integrated on-chip designs. Additionally, there may be challenges integrating the substrate removal step into the back-end-of-line commercial CMOS processing steps. Experimental validation of fabricated actuators demonstrates an improvement of 50x in switching time when compared to conventional step biasing results. Compared to theoretical calculations, the experimental results are in good agreement.

The robust device design of fringing-field electrostatic MEMS actuators results in inherently low squeeze-film damping conditions and long settling times when performing switching operations using conventional step biasing. Real-time switching time improvement with DC-dynamic waveforms reduces the settling time of fringing-field MEMS actuators when transitioning between up-to-down and down-to-up states.

Real-Time DC-dynamique Méthode de sollicitation pour Temps de commutation amélioration de franges champ gravement sous-amorti électrostatiques MEMS Actionneurs

Mechanically underdamped electrostatic fringing-field MEMS actuators are well known for their fast switching operation in response to a unit step input ...

How to Build a Vacuum Spring-transport Package for Spinning Rotor Gauges

The spinning rotor gauge (SRG) is a high-vacuum gauge often used as a secondary or transfer standard for vacuum pressures in the range of 1.0 x 10-4 Pa to 1.0 Pa. In this application, the SRGs are frequently transported to laboratories for calibration. Events can occur during transportation that change the rotor surface conditions, thus changing the calibration factor. To assure calibration stability, a spring-transport mechanism is often used to immobilize the rotor and keep it under vacuum during transport. It is also important to transport the spring-transport mechanism using packaging designed to minimize the risk of damage during shipping. In this manuscript, a detailed description is given on how to build a robust spring-transport mechanism and shipping container. Together these form a spring-transport package. The spring-transport package design was tested using drop-tests and the performance was found to be excellent. The present spring-transport mechanism design keeps the rotor immobilized when experiencing shocks of several hundred g (g = 9.8 m/sec2 and is the acceleration due to gravity), while the shipping container assures that the mechanism will not experience shocks greater than about 100 g during common shipping mishaps (as defined by industry standards).

Here we describe how to build a robust spring-transport mechanism for a spinning rotor gauge. This device securely immobilizes the rotor and keeps it under vacuum during transportation. We also describe packaging that minimizes the risk of damage during transport. Tests show our design works for typical shocks during transport.

Comment construire un printemps de transport Paquet à vide pour Spinning Rotor Jauges

The spinning rotor gauge (SRG) is a high-vacuum gauge often used as a secondary or transfer standard for vacuum pressures in the range of 1.0 x 10-4 Pa to ...

Digital Printing of Titanium Dioxide for Dye Sensitized Solar Cells

Silicon solar cell manufacturing is an expensive and high energy consuming process. In contrast, dye sensitized solar cell production is less environmentally damaging with lower processing temperatures presenting a viable and low cost alternative to conventional production. This paper further enhances these environmental credentials by evaluating the digital printing and therefore additive production route for these cells. This is achieved here by investigating the formation and performance of a metal oxide photoelectrode using nanoparticle sized titanium dioxide. An ink-jettable material was formulated, characterized and printed with a piezoelectric inkjet head to produce a 2.6 &#181;m thick layer. The resultant printed layer was fabricated into a functioning cell with an active area of 0.25 cm2 and a power conversion efficiency of 3.5%. The binder-free formulation resulted in a reduced processing temperature of 250 &#176;C, compatible with flexible polyamide substrates which are stable up to temperatures of 350 &#730;C. The authors are continuing to develop this process route by investigating inkjet printing of other layers within dye sensitized solar cells.

This paper investigates the suitability of inkjet printing for the manufacturing of dye-sensitized solar cells. A binder-free TiO2 nanoparticle ink was formulated and printed onto a FTO glass substrate. The printed layer was fabricated into a cell with an active area of 0.25 cm2 and an efficiency of 3.5%.

Impression numérique de dioxyde de titane pour les cellules solaires à colorant

Silicon solar cell manufacturing is an expensive and high energy consuming process. In contrast, dye sensitized solar cell production is less ...

Ultrasonic Fatigue Testing in the Tension-Compression Mode

Ultrasonic fatigue testing is one of a few methods which allow investigating fatigue properties in the ultra-high cycle region. The method is based on exposing the specimen to longitudinal vibrations on its resonance frequency close to 20 kHz. With use of this method, it is possible to significantly decrease the time required for the test, when compared to conventional testing devices usually working at frequencies under 200 Hz. It is also used to simulate loading of material during operation in high speed conditions, such as those experienced by components of jet engines or car turbo pumps. It is necessary to operate only in the high and ultra-high cycle region, due to the possibility of extremely high deformation rates, which can have a significant influence on the test results. Specimen shape and dimensions have to be carefully selected and calculated to fulfill the resonance condition of the ultrasonic system; thus, it is not possible to test the full components or specimens of arbitrary shape. Before each test, it is necessary to harmonize the specimen with the frequency of the ultrasonic system to compensate for deviations of the real shape from the ideal one. It is not possible to run a test until a total fracture of the specimen, since the test is automatically terminated after initiation and propagation of the crack to a certain length, when the stiffness of the system changes enough to shift the system out of the resonance frequency. This manuscript describes the process of evaluation of materials' fatigue properties at high-frequency ultrasonic fatigue loading with use of mechanical resonance at a frequency close to 20 kHz. The protocol includes a detailed description of all steps required for a correct test, including specimen design, stress calculation, harmonizing with the resonance frequency, performing the test, and final static fracture.

A protocol for ultrasonic fatigue testing in the high and ultra-high cycle region in axial tension-compression loading mode.

Ultrasons Fatigue Testing dans le Mode de traction-Compression

Ultrasonic fatigue testing is one of a few methods which allow investigating fatigue properties in the ultra-high cycle region. The method is based on ...

Combining Microfluidics and Microrheology to Determine Rheological Properties of Soft Matter during Repeated Phase Transitions

The microstructure of soft matter directly impacts macroscopic rheological properties and can be changed by factors including colloidal rearrangement during previous phase changes and applied shear. To determine the extent of these changes, we have developed a microfluidic device that enables repeated phase transitions induced by exchange of the surrounding fluid and microrheological characterization while limiting shear on the sample. This technique is &#181;2rheology, the combination of microfluidics and microrheology. The microfluidic device is a two-layer design with symmetric inlet streams entering a sample chamber that traps the gel sample in place during fluid exchange. Suction can be applied far away from the sample chamber to pull fluids into the sample chamber. Material rheological properties are characterized using multiple particle tracking microrheology (MPT). In MPT, fluorescent probe particles are embedded into the material and the Brownian motion of the probes is recorded using video microscopy. The movement of the particles is tracked and the mean-squared displacement (MSD) is calculated. The MSD is related to macroscopic rheological properties, using the Generalized Stokes-Einstein Relation. The phase of the material is identified by comparison to the critical relaxation exponent, determined using time-cure superposition. Measurements of a fibrous colloidal gel illustrate the utility of the technique. This gel has a delicate structure that can be irreversibly changed when shear is applied. &#181;2rheology data shows that the material repeatedly equilibrates to the same rheological properties after each phase transition, indicating that phase transitions do not play a role in microstructural changes. To determine the role of shear, samples can be sheared prior to injection into our microfluidic device. &#181;2rheology is a widely applicable technique for the characterization of soft matter enabling the determination of rheological properties of delicate microstructures in a single sample during phase transitions in response to repeated changes in the surrounding environmental conditions.

We demonstrate the fabrication and use of a microfluidic device that enables multiple particle tracking microrheology measurements to study the rheological effects of repeated phase transitions on soft matter.

Combinant la microfluidique et microrhéologie pour déterminer les propriétés rhéologiques de la matière molle au cours de Transitions de phases répétées

The microstructure of soft matter directly impacts macroscopic rheological properties and can be changed by factors including colloidal rearrangement ...

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.

Fabrication de dispositifs de réfraction-index-assortie de microfluidique biomédicale

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

Crack Monitoring in Resonance Fatigue Testing of Welded Specimens Using Digital Image Correlation

A procedure using digital image correlation (DIC) to detect cracks on welded specimens during fatigue tests on resonance testing machines is presented. It is intended as a practical and reproducible procedure to identify macroscopic cracks at an early stage and monitor crack propagation during fatigue tests. It consists of strain field measurements at the weld using DIC. Images are taken at fixed load cycle intervals. Cracks become visible in the computed strain field as elevated strains. This way, the whole width of a small-scale specimen can be monitored to detect where and when a crack initiates. Subsequently, it is possible to monitor the development of the crack length. Because the resulting images are saved, the results are verifiable and comparable. The procedure is limited to cracks initiating at the surface and is intended for fatigue tests under laboratory conditions. By visualizing the crack, the presented procedure allows direct observation of macrocracks from their formation until rupture of the specimen.

Digital image correlation is used in fatigue tests on a resonance testing machine to detect macroscopic cracks and monitor crack propagation in welded specimens. Cracks on the specimen surface become visible as increased strains.

Surveillance des fissures dans les tests de fatigue par résonance des spécimens soudés à l'aide de la corrélation d'image numérique

A procedure using digital image correlation (DIC) to detect cracks on welded specimens during fatigue tests on resonance testing machines is presented. It ...

Automated Delivery of Microfabricated Targets for Intense Laser Irradiation Experiments

Described is an experimental procedure that enables high-power laser irradiation of microfabricated targets. Targets are brought to the laser focus by a closed feedback loop that operates between the target manipulator and a ranging sensor. The target fabrication process is explained in detail. Representative results of MeV-level proton beams generated by irradiation of 600 nm thick gold foils at a rate of 0.2 Hz are given. The method is compared with other replenishable target systems and the prospects of increasing the shot rates to above 10 Hz are discussed.

A protocol is presented for automated irradiation of thin gold foils with high intensity laser pulses. The protocol includes a step-by-step description of the micromachining target fabrication process and a detailed guide for how targets are brought to the laser&#39;s focus at a rate of 0.2 Hz.

Livraison automatisée de cibles microfabriquées pour des expériences intenses d’irradiation laser

Described is an experimental procedure that enables high-power laser irradiation of microfabricated targets. Targets are brought to the laser focus by a ...