Ringraziamo la Fondazione Lindback per il sostegno finanziario, e il dottor Alexander Sidorenko e Elza Chu per le discussioni fruttuose e assistenza tecnica, e il professor Robert Smith per l&#39;assistenza con la C. saggi elegans.

NOTA: Nelle procedure descritte di seguito, le linee guida di sicurezza di laboratorio devono essere sempre seguite. Di particolare importanza è la sicurezza quando si tratta di alta tensione (&gt; 500 V) e prodotti chimici di trattamento. 1. Rivestimento di un substrato conduttivo con la candela fuliggine <ol><li> Taglio di metallo in rame in rettangoli (75 x 43 mm, spessore di 0,5 mm). Pulire ogni substrato di rame per immersione in mordenzante di rame per circa 30 secondi, lavare con acqua corrente per circa 20 secondi, e asciugare con carta. NOTA: Se si utilizza il metodo 1 di seguito, cambiare le dimensioni di 75 x 25 mm per adattarsi alla macchina. </li><li> Sweep una candela di paraffina candela sotto il substrato di rame per 30-45 secondi, per ottenere un rivestimento di fuliggine approssimativamente uniforme (spessore di circa 40 micron). Mantenere il substrato ~ 1 cm all&#39;interno della fiamma. Non toccare la superficie di fuliggine fragile. </li></ol> 2. Proteggere lo strato di fuliggine con rivestimento NOTA: Lo strato di fuliggine è molto fragileE deve essere ricoperta per protezione. Due alternative semplici (metodi 1 e 2 di seguito) sono suggeriti qui, ma i protocolli più robusti sono attualmente in fase di sviluppo. <ol><li> Metodo 1 <ol><li> Caricare il campione nell&#39;evaporatore metallo o sistema di sputtering. Seguendo le procedure di funzionamento del sistema, evacuare la camera, e inizia la deposizione controllata di oro sullo strato di fuliggine (150-200 nm). Lasciare raffreddare l&#39;apparecchio a temperatura ambiente. </li><li> Dip-coat substrato metallizzato in una soluzione di 1-dodecantiolo (1% v / v, in etanolo al 95%, ACS / USP grado), per 10 min all&#39;interno di una cappa chimica. Quindi, tenendo il dispositivo ad un angolo vicino a 60 °, lavare delicatamente la superficie con diverse gocce di solo etanolo. Lasciate che i dispositivi a secco, durante la notte. </li></ol></li><li> Metodo 2 <ol><li> In una cappa chimica, subito dopo il rivestimento del substrato di fuliggine e mentre il substrato è ancora calda della fiamma candela, versare alcune gocce di liquido fluorurato su un lato dellasubstrato, e inclinare il substrato ad un angolo di circa 90 °. Deposita più gocce, e far rotolare su tutta la superficie di fuliggine. NOTA: Quando la goccia cade su un punto, la fuliggine verrà spazzato via da quella zona. Lasciare le goccioline di liquido fluorurato diffusione il più possibile. </li><li> Cuocere il substrato su una piastra calda (160 ° C per 15 min) all&#39;interno di una cappa chimica. </li><li> Lasciate che il substrato sedersi durante la notte a temperatura ambiente prima dell&#39;uso. Conservare a tempo indeterminato. </li></ol></li></ol> 3. Realizzazione di Top elettrodi (adattato da Abdelgawad et al. 12) <ol><li> Disegnare gli elettrodi che utilizzano software di progettazione grafica. Ciascun elettrodo è lungo 2 mm di larghezza 0,3 mm, e la distanza tra gli elettrodi è di 0,3 mm. Il divario tra i contatti (a scatto nel connettore, vedi sotto) è di 2,3 mm (figura 1). </li><li> Tagliare un laminato di rame flessibile (35 micron di spessore) nel formato di Monarch (3,87 x 7,5 pollici). Utilizzare altre dimensioni if compatibile con la stampante. Caricare il laminato nel vassoio di alimentazione manuale di una stampante a colori. </li><li> Assicurarsi di utilizzare &quot;nero ricco&quot;, o &quot;Registrazione nero&quot;, quando si stampa su foglio di rame (vedi Abdelgawad et al. 12 per i dettagli) per consentire uno strato più denso di inchiostro nero sul supporto di rame, proteggendo il motivo stampato durante l&#39;incisione . Lasciate che il supporto stampato asciugare completamente, durante la notte. </li><li> All&#39;interno di una cappa chimica, riscaldamento (40 ° C) un becher con 50 ml di mordenzante rame. Immergere il laminato stampato nel bicchiere, e agitare delicatamente nella soluzione per circa 10 min. Tempo di attacco dipende dalla soluzione mordenzante rame. Ogni pochi minuti, controllare la corrosione e vedere se il modello è intatto. </li><li> Lavare accuratamente il laminato con acqua e rimuovere il rivestimento con acetone ed etanolo nella cappa chimica. Lavare, ancora una volta, e asciugare delicatamente il laminato con il tovagliolo di carta. </li><li> Fissare accuratamente il laminato con elettrodi ad un glass slitta (75 x 25 mm, spessore di ~ 1 mm), con nastro biadesivo. Evitare di sacche d&#39;aria. </li><li> Attaccare un film di perfluoroalkoxy PFA agli elettrodi con i nastri. Questo serve per evitare contatti accidentali degli elettrodi con la goccia, che danneggia migliori elettrodi a causa di corto circuito. </li></ol> 4. L&#39;interfaccia elettronica (circuito in figura 2) <ol><li> Saldare i relè ed i condensatori C a un circuito universale. </li><li> Montare il resto dei 10 comandi dei relè di una breadboard per i circuiti elettronici. </li><li> Filo di ingresso ogni driver di relè a un canale nella scheda di controllo. </li><li> Scatto con attenzione i primi elettrodi in un connettore (Figura 3). Filo uscita ogni driver del relè ad un elettrodo superiore, come mostrato in figura. Si noti che esiste un connettore contatto a terra tra una coppia di fili dal relè, per minimizzare il rumore elettrico. NOTA: Il connettore si siede su una piattaforma regolabile per controllare tha distanza (0,1-0,5 mm) tra superiore e inferiore (fuliggine rivestito) substrato. </li><li> Utilizzare un programma per controllare la temporizzazione per alta tensione (HV) applicazione (circa 0,8 sec) a 4 elettrodi contemporaneamente, spostando 1 elettrodo nella direzione del moto (cioè per 0,8 secondi, azionare 1234, poi 2345, 3456, ecc ., 0.8 sec per ciascun gruppo, e poi indietro, si muove in modo gocciolina nella direzione opposta pure). </li></ol> 5. Visualizzazione Droplet e Manipolazione <ol><li> Per registrare il movimento gocciolina, utilizzare il sistema di visualizzazione, che si compone di un 24X - assemblaggio ingrandimento 96X combinato con una telecamera CCD. Collegare il videoregistratore alla fotocamera tramite S-video. </li><li> Pipettare una goccia 4 ml contenente C. elegans nel supporto sul fondo del substrato fuliggine rivestito. </li><li> Portare i primi elettrodi a ca 0.3 mm sopra la goccia. La gocciolina dovrebbe essere vicino al centro, proprio sotto il quinto elettrodi, per facilitare le operazioni. </li><li> Accendere l&#39;interfaccia elettronica e alta tensione (500 V RMS) e regolare la distanza elettrodo superiore alla goccia finché inizia a muoversi. Non lasciate che i primi elettrodi toccano la goccia. </li><li> Raccogliere dati registrando il numero di trasferimenti gocciolina successo sul dispositivo in risposta agli impulsi elettrici. Un esperimento di successo è caratterizzata da almeno 700 trasferimenti goccioline, cioè, un trasferimento dopo ogni impulso elettrico. </li><li> Raccogliere dati continuo, fino alla gocciolina non si muove più in risposta a 5 a 10 impulsi. NOTA: Quando la superficie comincia a degradare, il movimento potrebbe essere ripristinato portando i primi elettrodi più vicino alla goccia. </li></ol>

<ol>
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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. 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The authors declare that they have no competing financial interests.

La fase più critica del protocollo è la protezione dello strato di fuliggine, direttamente associata con il successo in goccioline movimento. Metallizzazione lo strato di fuliggine (precedenti metodi 1) permette di quasi il 100% di successo fabbricazione. Tuttavia, il tempo massimo di funzionamento è di circa 10 minuti; eventualmente, le frazioni delle gocce sono bagnare la fuliggine attraverso buchi nello strato di metallo. Rivestimento lo strato di fuliggine con il liquido fluorurato è l&#39;alternativa più sempl...

La miniaturizzazione dei dispositivi che funzionano con i liquidi è di fondamentale importanza per lo sviluppo di piattaforme &quot;lab-on-a-chip&quot;. In questo senso, gli ultimi due decenni hanno visto un significativo progresso nel campo della microfluidica, con una varietà di applicazioni. 1-5 contrasto con il trasporto di liquido nei canali chiusi (microfluidica canale), DMF manipola goccioline su array di elettrodi. Uno dei meriti più interessanti di questa tecnica è l&#39;assenza di parti mobili per il trasporto di fluidi, e il movimento è immediatamente fermato spegnendo segnali elettrici. Tuttavia, il movimento delle gocce dipende contenuti gocciolina, certamente una caratteristica indesiderabile per una piattaforma universale &quot;lab-on-a-chip&quot;. Goccioline contenenti proteine ​​e altri analiti aderire alle superfici dei dispositivi, diventando inamovibile. Probabilmente, questo è stato il limite maggiore per ampliare la gamma di applicazioni DMF; 6-8alternative per ridurre al minimo la formazione di incrostazioni di superficie indesiderato comportano l&#39;aggiunta di specie chimiche in più per la goccia o dei suoi dintorni, che potrebbe potenzialmente influenzare il contenuto delle gocce. In precedenza, il nostro gruppo ha sviluppato un dispositivo per consentire il trasporto di cellule e proteine ​​in DMF, senza additivi aggiunti (dispositivi di campo-DW). 9 Ciò è stato ottenuto combinando una superficie basata sulla candela fuliggine, 10 con una geometria dispositivo che favorisce goccia di rotolamento e conduce ad una forza verso l&#39;alto sul droplet, diminuendo ulteriormente l&#39;interazione gocciolina superficie. In questo approccio, il movimento gocciolina non è associato con bagnatura superficiale. 11 L&#39;obiettivo del metodo dettagliato di seguito descritto è quello di realizzare un dispositivo DMF in grado di trasportare goccioline contenenti proteine, cellule e interi organismi, senza additivi supplementari. I dispositivi di campo-DW aprono la strada per le piattaforme interamente controllate di lavoro in gran parte indipendentemente goccia chimicory. Qui, anche simulazioni presenti mostrando che, nonostante l&#39;alta tensione necessaria per il funzionamento del dispositivo, la caduta di tensione attraverso la goccia è una piccola frazione della tensione applicata, indicando effetti trascurabili sulla bioanalytes all&#39;interno della gocciolina. Infatti, prove preliminari con Caenorhabditis elegans (C. elegans), un nematode utilizzato per una varietà di studi in biologia, mostrano che i vermi nuotano indisturbati come vengono applicate tensioni.

<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.

In precedenza, abbiamo utilizzato i dispositivi di campo-DW per consentire il movimento delle proteine ​​in DMF. In particolare, goccioline con albumina di siero bovino (BSA) possono essere spostati ad una concentrazione di 2000 volte superiore a quanto precedentemente riportato da altri autori (senza additivi). Ciò è dovuto alla ridotta interazione tra la goccia e la superficie; la figura 4 mostra una gocciolina contenente fluorescente-tag BSA (vedi Freire et al 9 per ulterior...

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.

Approfittando di ridotta interazione Droplet-superficie per ottimizzare il trasporto di Bioanalytes in microfluidica 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 Views.  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.

Video: 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.

Valutare plasmoniche Trasporti in Current-carrying Argento Nanowires

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.

Caratterizzazione dei Trasporti termali in materiali solidi monodimensionali

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-dinamica Metodo di polarizzazione per il tempo di commutazione miglioramento Severamente sottosmorzato frangente campo elettrostatico MEMS Attuatori

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.

Come costruire un vuoto primavera-trasporto Pacchetto per la filatura rotore Indicatori

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%.

La stampa digitale di biossido di titanio per le celle solari dye sensibilizzato

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.

Prova in modalità trazione-compressione ad ultrasuoni di fatica

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.

Combinazione di microfluidica e Microrheology per determinare le proprietà reologiche dei materiali molli durante le transizioni di fase ripetute

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.

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 ...

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.

Monitoraggio delle crepe nei test di fatica di risonanza di campioni saldati utilizzando la correlazione digitale delle immagini

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.

Consegna automatizzata di bersagli microfabbricati per intensi esperimenti di irradiazione laser

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