The authors acknowledge support from Samsung, the NC State Chancellors Innovation Funds, NSF (CAREER CMMI-0954321 and Triangle MRSEC DMR-1121107), and Air Force Research Labs.

1. La manipolazione della tensione superficiale del metallo liquido in elettrolita <ol><li> Ossidazione <ol><li> Versare un elettrolita acquoso (acida o basica) in una capsula di Petri. Per assicurare che l&#39;ossido viene completamente rimosso, usare un acido o base con una concentrazione maggiore di 0.1 M 24 (ad esempio 1 M NaOH o HCl 1 M). Utilizzare un volume che riempirà il piatto ad una profondità di circa 1-3 mm. Evitare il contatto con la pelle con queste soluzioni. </li><li> Utilizzare una siringa per una goccia (ottimale tra 10-500 microlitri) di una lega a base di gallio-nell&#39;elettrolita. Gli esempi includono eutettica di gallio indio (eGain) o di gallio indio e stagno (Galinstan). Se si utilizza gallio puro, riscaldare l&#39;elettrolita ad almeno 30 ° C per evitare il congelamento. </li><li> Collocare un filo di rame nel metallo liquido per stabilire l&#39;elettrodo di lavoro. Utilizzare un filo di rame di diametro inferiore a quello della goccia, e utilizzare un multimetro digitale secondo le istruzioni del produttore e perNsure che il filo ha una resistenza di &lt;1 Ω. In acida o basica, il metallo liquido bagnare il rame e quindi formare un eccellente contatto elettrico. </li><li> Inserire una conduzione controelettrodo (ad esempio il rame, grafite, platino, ecc) nella soluzione, ma non a contatto con il metallo liquido. Se il controelettrodo ha una resistenza di &lt;1 Ω, le sue dimensioni sono irrilevanti. </li><li> Collegare i fili ad una sorgente di tensione e applicare un potenziale positivo al metallo liquido. Per piccola deformazione forma, applicare tensioni positive &lt;1 V. Per maggiore deformazione forma (e il movimento del metallo liquido verso il controelettrodo), applicare&gt; 1 V. Nota: La concentrazione della soluzione e la distanza della goccia dal controelettrodo dettare la tensione necessaria per indurre variazioni di tensione interfacciale poiché il tasso di ossidazione superficiale elettrochimica compete con il tasso di ossido di dissoluzione con l&#39;elettrolita. </li></ol></li&gt; <li> Riduzione <ol><li> Versare una goccia (10-500 ml) del metallo liquido da una siringa in una piastra di Petri vuota. </li><li> Versare un elettrolita acquoso neutro nella capsula Petri (es 1 M fluoruro di sodio (NaF) o 1 M di cloruro di sodio (NaCl)) ad un livello che sommerge il metallo. Nota: l&#39;uso di un acido (pH &lt;3) o soluzione basica (pH&gt; 10) provoca l&#39;ossido di sciogliere spontaneamente. </li><li> Collocare un filo di rame nel metallo liquido per agire come elettrodo di lavoro, e un filo conduttore (per esempio, rame) nell&#39;elettrolita di agire come controelettrodo. </li><li> Collegare i fili ad una sorgente di tensione e applicare un potenziale negativo al metallo liquido. Applicare circa -1 V per rimuovere l&#39;ossido superficiale e causare il metallo Dewet dal substrato. Il metallo dovrebbe Dewet sul lato più vicino al controelettrodo. </li><li> Applicare potenziali più negativi (&lt;-1 V) per rimuovere completamente lo strato di ossido. Evitare l&#39;applicazione excessivamente grandi tensioni negative per evitare bolle di idrogeno di apparire sul metallo liquido a causa della riduzione dell&#39;elettrolito. </li></ol></li></ol> 2. tensione superficiale Misura via Sessile Droplet <ol><li> Utilizzando un cutter laser o fresa, tagliare un percorso diretto dal centro verso il bordo di un pezzo di polimetilmetacrilato (PMMA) (~ 1 mm di spessore) Non tagliare il percorso tutto il percorso attraverso lo spessore del PMMA.; tagliare solo a metà. Questo pezzo servirà come substrato per il metallo liquido. Altri materiali piatti e isolanti, quali vetro, ceramiche, o polimeri possono anche servire come substrato. </li><li> Con lo stesso strumento, un foro 1 mm 2 attraverso il centro del PMMA. </li><li> Utilizzando il percorso come guida, eseguire un filo di rame isolato con solo la punta esposta al centro del PMMA. Posizionare il filo in modo che sporga sulla superficie PMMA. Sigillare il filo in posizione con un adesivo a tenuta. Tagliareil filo appena sopra la superficie del PMMA, ma non lasciare che sia troppo prolungata (oltre ~ 100 micron) o disturbare la forma della goccia. </li><li> Tape pezzo PMMA giù in un contenitore trasparente attraverso cui un&#39;immagine chiara può essere ottenuto. Riempire il contenitore con 1 M NaOH, e una goccia 25-50 ml di metallo liquido sul filo di rame sporgente. Questo filo servirà come elettrodo di lavoro e bagnerà la goccia. </li><li> Posizionare una rete di platino controelettrodo e saturo di argento / cloruro di argento (Ag / AgCl) elettrodo di riferimento nella soluzione. Collegare tutti gli elettrodi ad un potenziostato. </li><li> Posizionare il contenitore in un goniometro angolo di contatto in modo che il profilo superficiale della goccia è chiaramente visibile. Utilizzare il potenziostato per controllare la tensione rispetto all&#39;elettrodo di riferimento, e utilizzare il goniometro per misurare la forma e quindi la tensione interfacciale della goccia. Assicurarsi che il goniometro è in grado di misurare goccia sessile Tensi interfaccialein data; è anche possibile utilizzare l&#39;analisi di forma assialsimmetrica personalizzata di immagini goccia prese da una telecamera montata orizzontalmente 25. </li></ol> 3. capillare Iniezione <ol><li> Riempire un capillare di vetro con una soluzione di NaOH 1 M. Il diametro capillare deve essere ~ 1 mm. </li><li> Posizionare un&#39;estremità del filo capillare contro una goccia di metallo liquido. Allineate il capillare in modo che sia parallelo alla superficie del tavolo (cioè perpendicolare alla gravità). Evitare di vuoti d&#39;aria tra la caduta di metallo liquido e capillare elettrolita-riempita. Utilizzando un wipe, tamponare fuori qualsiasi elettrolita in eccesso che possono essere trapelato durante il montaggio. </li><li> Collocare un filo di rame (elettrodo di lavoro) nel metallo liquido, e un conduttore controelettrodo (ad esempio filo di rame) nell&#39;estremità aperta del capillare in modo da essere a contatto la soluzione. </li><li> Collegare i fili ad una sorgente di tensione e applicare un potenziale positivo al metallo liquido. Il metallo liquido deve iniziare il riempimento della capillary (evitare grandi potenzialità che causeranno la formazione di bolle in eccesso sul bancone-elettrodi). </li></ol> 4. capillare Ritiro <ol><li> Utilizzare morbide tecniche litografiche 26 e replica di stampaggio per fabbricare canali microfluidica composti di polidimetilsilossano (PDMS). Realizzare canali che sono circa 100 a 1.000 micron di larghezza 100 micron, alti, e 25 a 65 mm di lunghezza. Nota: Canale Dimensioni 1.000 micron di larghezza, 100 micron di altezza, e 65 mm lungo il canale ha prodotto risultati coerenti, ma altri possono anche funzionare. In alternativa, utilizzare capillari di vetro (ad esempio, 1 mm di diametro, in vetro borosilicato) invece di microcanali PDMS. </li><li> Iniettare metallo liquido manualmente o utilizzando una pompa a siringa per riempire completamente il canale (cioè, 6.5 mm 3 per 1.000 micron di larghezza, 100 micron di altezza e 65 mm di canale lungo). </li><li> Usando un batuffolo di cotone che è stato immerso in 1 M NaOH o 1 M HCl, rimuovere una quantità eccessiva di Limetallo quid dall&#39;ingresso (e, se necessario, l&#39;uscita) del canale, in modo che il metallo rimane a filo con la superficie superiore dei PDMS. </li><li> Immergere una estremità del canale in elettroliti (ad esempio 1 M NaCl), e posizionare l&#39;anodo (ad esempio, fili di rame, platino, o tungsteno) tale che tocchi l&#39;elettrolita ma non il metallo. </li><li> All&#39;altra estremità del canale, contattare un elettrodo separato (per esempio, filo Cu) alla superficie metallica modo che il metallo liquido stesso funge da catodo. </li><li> Collegate questi fili (cioè, anodo e catodo) ad una sorgente di tensione o potenziostato, e completare il circuito elettrico. Per un sistema a tre elettrodi, posizionare l&#39;elettrodo di riferimento in modo tale che sommerge malapena nella goccia di elettrolita. </li><li> Prima di applicare una tensione riducendo, montare una videocamera su un treppiede o in un microscopio per registrare gli esperimenti. Utilizzare la modalità autofocus per ottenere tutto a fuoco. Utilizzare fuoco manuale per avere un migliore controlloprofondità di campo, il bilanciamento del bianco, e ISO. Se necessario, utilizzare arresto F superiore (ossia, 11 o superiore), 1/100 dell&#39;otturatore, bilanciamento automatico del bianco e ISO automatica. </li><li> Avviare la registrazione l&#39;esperimento. Applicare circa -1 V di ritirare il metallo liquido dai microcanali. Girare la tensione fuori per causare il metallo a fermarsi in elettrolita neutro. </li></ol>

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The authors have nothing to disclose.

<html> Questo metodo controlla la tensione superficiale di metalli liquidi a base di gallio-utilizzando piccole tensioni per guidare la deposizione e la rimozione di un ossido superficiale. Anche se il metodo funziona solo in soluzioni elettrolitiche, è semplice, e lavora in un&#39;ampia varietà di condizioni diverse, ma ci sono sottigliezze degne di nota. In assenza di potenziale elettrico, sia soluzioni acide e basiche etch via l&#39;ossido 27. L&#39;applicazione di un potenziale ossidativo guida la formaz...

This method provides a simple way to control the surface tension of liquid metals containing gallium. The method uses modest voltages (~1 V) applied directly to the liquid metal (relative to a counter electrode in the presence of electrolyte) to achieve enormous and reversible changes to the surface tension of the metal1. 
Surface tension is a dominant force for liquids at small length scales and is important for a number of capillary phenomena including wetting, spreading, and surface-tension driven flow. Consequently, the ability to control surface tension is a sensible way to manipulate the shape, position, and flow of liquids at sub-mm length scales. The most common way to alter surface tension between two fluids is to use a surfactant, which is a molecule that spans the interface between the fluids. Surfactants lower surface tension, but in a way that is not easy to reverse since it is difficult to remove surfactants from the interface. Surface tension can also be altered using a variety of techniques, including temperature gradients2,3, light4, surface chemistry5-7,and voltage8. But most of these methods result in modest changes to surface tension, particularly for liquid metals, which have notably large surface tensions.
The ability to control the surface tension of liquid metal could enable new opportunities for creating shape reconfigurable structures with metallic properties for electronic, thermal, and optical applications9-14. The most common liquid metal is Hg, which is noted for its toxicity. The methods described here are relevant for liquid metals based on gallium. These metals have low viscosity, large surface tension, low volatility (low vapor pressure), and low toxicity15. Importantly, these metals form surface oxides composed of gallium oxide that are a few nm thick in air16. This oxide layer creates a physical skin that historically has been a nuisance for electrochemical and fluid dynamic applications17. The method here utilizes the oxide in new ways to control surface tension.
The most common way to manipulate liquid metals in electrolyte is to apply a potential to the metal relative to a counter electrode18. Oppositely charged ions from the electrolyte match the charges on the metal, causing the interfacial tension to drop. This phenomenon-termed electrocapillarity-has been known since the 1870s as described by Lippman19and has been utilized for alloys of gallium20. Typically, electrocapillarity achieves modest changes to surface tension, since undesirable electrochemical reactions limit the range of voltages applied to the metal. In contrast, the method described here utilizes the surface oxidation of the metal (or conversely, the reduction of the surface oxide) as a way to achieve enormous changes in surface tension above and beyond changes resulting from electrocapillarity. The leading explanation for this phenomenon is that the oxide is asymmetric; that is, the outer surface of the oxide terminates with hydroxyl groups (making a low interfacial tension interface with the aqueous electrolyte), and the interior surface of the oxide terminates with gallium atoms (making a low interfacial tension interface with the metal). In contrast, the removal of the oxide via electrochemical reduction results in a bare metal-electrolyte interface, which returns the metal back to a state of high surface tension. We characterize the interfacial tension of the metal by analyzing the shape of sessile droplets as a function of voltage while assuming that gravity and surface tension are the dominant forces that define the curvature of its surface. 
The advantage of this technique relative to classic electrocapillarity is that it can reversibly tune the tension of low toxicity liquid metals over enormous ranges (from ~500 mN/m to near zero). This delta change in surface tension may be the largest ever reported in literature for any fluid and it can be accomplished in a tunable and reversible manner. These large changes in surface tension are useful for manipulating the capillary behavior of metals; for example, it can induce the metal to spread on a surface, withdraw the metal from microchannels, fill microchannels with metal, and overcome the Rayleigh instabilities to form liquid metal fibers1,21. 
A drawback of this technique is that it requires electrolyte. It works best in acidic or basic conditions, because these electrolytes remove excess surface oxide that would otherwise contaminate the surface of the metal and mechanically restrict the movement of the metal. The simultaneous removal and deposition of the oxide layer complicates the analysis of the interfacial phenomena and it is our hope the methods described in this paper empowers additional analysis. Another disadvantage is that the electrochemical reactions at the surface of the metal must be matched by complimentary half-reactions at the counter electrode22,23. This can lead to hydrogen bubbles forming at the counter electrode.

<table><tbody><tr><td>Eutectic Gallium Indium</td><td>Indium Corporation</td><td></td><td></td></tr><tr><td>Sodium Hydroxide</td><td>Fisher Scientific</td><td>2318-3</td><td></td></tr><tr><td>Hydrochloric Acid</td><td>Fisher Scientific</td><td>A481-212</td><td></td></tr><tr><td>Sodium Fluoride</td><td>Sigma-Aldrich</td><td>201154</td><td></td></tr><tr><td>Optical Adhesive</td><td>Norland</td><td>NOA81</td><td></td></tr><tr><td>Polydimethylsiloxane (Sylgard-184)</td><td>Dow Corning</td><td></td><td>Silicone Elastomer Kit</td></tr><tr><td>Borosilicate Glass Capillaries</td><td>Friedrich and Dimmoch</td><td>B41972</td><td></td></tr><tr><td>Ag/AgCl Reference Electrode</td><td>Microelectrodes Inc.</td><td>MI-401F</td><td></td></tr><tr><td>Voltage Source</td><td>Keithley</td><td>3390</td><td></td></tr><tr><td>Potentiostat</td><td>Gamry</td><td>Ref 600</td><td></td></tr><tr><td>Laser Cutter</td><td>Universal Laser Systems</td><td>VLS 3.50</td><td></td></tr></tbody></table>

a method to manipulate surface tension of a liquid metal via surface oxidation and reduction

Controllo tensione interfacciale è un metodo efficace per manipolare la forma, la posizione e il flusso di fluidi su scale sub-millimetriche, dove tensione interfacciale è una forza dominante. Una varietà di metodi esistenti per il controllo della tensione interfacciale di liquidi acquosi e biologici su questa scala; Tuttavia, queste tecniche hanno un&#39;utilità limitata per metalli liquidi a causa della loro grande tensione interfacciale. Metalli liquidi possono formare componenti morbide, estensibili, e di forma-riconfigurabile in dispositivi elettronici ed elettromagnetici. Sebbene sia possibile manipolare questi fluidi attraverso metodi meccanici (ad esempio, di pompaggio), metodi elettrici sono più facili da miniaturizzare, controllo e attuazione. Tuttavia, la maggior parte delle tecniche elettrici hanno i loro limiti: elettrowetting-on-dielettrico richiede grandi (kV) potenzialità di modesta attuazione, electrocapillarity può incidere relativamente piccoli cambiamenti nella tensione superficiale, e ele continuactrowetting è limitata alle spine del metallo liquido in capillari. Qui, presentiamo un metodo per l&#39;azionamento di gallio e leghe metalliche liquido a base di gallio-via una reazione superficiale elettrochimica. Controllo del potenziale elettrochimico sulla superficie del metallo liquido in elettrolita rapidamente e reversibilmente cambia la tensione interfacciale di oltre due ordini di grandezza (̴500 mN / m quasi a zero). Inoltre, questo metodo richiede solo un potenziale molto modesta (&lt;1 V) applicato relativamente ad un controelettrodo. La variazione conseguente tensionamento è dovuto principalmente alla deposizione elettrochimica di uno strato di ossido superficiale, che agisce come un tensioattivo; rimozione dell&#39;ossido aumenta la tensione interfacciale, e viceversa. Questa tecnica può essere applicata in una vasta gamma di elettroliti ed è indipendente dal substrato su cui poggia.

Figura 1 A mostra un esempio della semplice tecnica a due elettrodi per l&#39;ossidazione e riduzione. In questo caso, una goccia 70 ml di metallo liquido in una camera 1 M NaOH soluzione entra in contatto un filo di rame per formare una connessione elettrica. Il 1 M NaOH rimuove l&#39;ossido superficiale del metallo e permette il metallo da bordare fino a causa della sua tensione interfacciale. L&#39;applicazione di un potenziale 2...

Watch this Scientific Journal Video about A Method to Manipulate Surface Tension of a Liquid Metal via Surface Oxidation and Reduction at JoVE.com

A Method to Manipulate Surface Tension of a Liquid Metal via Surface Oxidation and Reduction

Un metodo per manipolare Tensione superficiale di un metallo liquido tramite ossidazione superficiale e riduzione

We present a method to control the interfacial energy of a liquid metal in an electrolyte via electrochemical deposition (or removal) of a surface oxide layer. This simple method can control the capillary behavior of gallium-based liquid metals by tuning the interfacial energy rapidly, significantly, and reversibly using modest voltages.

Controlling interfacial tension is an effective method for manipulating the shape, position, and flow of fluids at sub-millimeter length scales, where ...

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15.2K Views.  North Carolina State University. We present a method to control the interfacial energy of a liquid metal in an electrolyte via electrochemical deposition (or removal) of a surface oxide layer. This simple method can control the capillary behavior of gallium-based liquid metals by tuning the interfacial energy rapidly, significantly, and reversibly using modest voltages.

Video: A Method to Manipulate Surface Tension of a Liquid Metal via Surface Oxidation and Reduction

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.

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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Ultrasound Velocity Measurement in a Liquid Metal Electrode

A growing number of electrochemical technologies depend on fluid flow, and often that fluid is opaque. Measuring the flow of an opaque fluid is inherently more difficult than measuring the flow of a transparent fluid, since optical methods are not applicable. Ultrasound can be used to measure the velocity of an opaque fluid, not only at isolated points, but at hundreds or thousands of points arrayed along lines, with good temporal resolution. When applied to a liquid metal electrode, ultrasound velocimetry involves additional challenges: high temperature, chemical activity, and electrical conductivity. Here we describe the experimental apparatus and methods that overcome these challenges and allow the measurement of flow in a liquid metal electrode, as it conducts current, at operating temperature. Temperature is regulated within &#177;2 &#176;C using a Proportional-Integral-Derivative (PID) controller that powers a custom-built furnace. Chemical activity is managed by choosing vessel materials carefully and enclosing the experimental setup in an argon-filled glovebox. Finally, unintended electrical paths are carefully prevented. An automated system logs control settings and experimental measurements, using hardware trigger signals to synchronize devices. This apparatus and these methods can produce measurements that are impossible with other techniques, and allow optimization and control of electrochemical technologies like liquid metal batteries.

Ultrasound velocimetry is used to study mixing by fluid flow in liquid metal electrodes. The focus of this manuscript is to illustrate the methods used for making precise, spatially-resolved ultrasound measurements while limiting oxidation and controlling and monitoring temperature, applied current, and the heater power being supplied.

Ultrasuoni misura di velocità in un metallo elettrodo Liquid

A growing number of electrochemical technologies depend on fluid flow, and often that fluid is opaque. Measuring the flow of an opaque fluid is inherently ...

Selective Area Modification of Silicon Surface Wettability by Pulsed UV Laser Irradiation in Liquid Environment

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of biosensing devices. We report on a protocol of using KrF and ArF lasers irradiating Si (001) samples immersed in a liquid environment with low number of pulses and operating at moderately low pulse fluences to induce Si wettability modification. Wafers immersed for up to 4 hr in a 0.01% H2O2/H2O solution did not show measurable change in their initial contact angle (CA) ~75&#176;. However, the 500-pulse KrF and ArF lasers irradiation of such wafers in a microchamber filled with 0.01% H2O2/H2O solution at 250 and 65 mJ/cm2, respectively, has decreased the CA to near 15&#176;, indicating the formation of a superhydrophilic surface. The formation of OH-terminated Si (001), with no measurable change of the wafer&#8217;s surface morphology, has been confirmed by X-ray photoelectron spectroscopy and atomic force microscopy measurements. The selective area irradiated samples were then immersed in a biotin-conjugated fluorescein-stained nanospheres solution for 2 hr, resulting in a successful immobilization of the nanospheres in the non-irradiated area. This illustrates the potential of&#160;the method for selective area biofunctionalization and fabrication of advanced Si-based biosensing architectures. We also describe a similar protocol of irradiation of wafers immersed in methanol (CH3OH) using ArF laser operating at pulse fluence of 65 mJ/cm2 and in situ formation of a strongly hydrophobic surface of Si (001) with the CA of 103&#176;. The XPS results indicate ArF laser induced formation of Si&#8211;(OCH3)x compounds responsible for the observed hydrophobicity. However, no such compounds were found by XPS on the Si surface irradiated by KrF laser in methanol, demonstrating the inability of the KrF laser to photodissociate methanol and create -OCH3 radicals.

We report on a process of in situ alteration of HF treated Si (001) surface into a hydrophilic or hydrophobic state by irradiating samples in microfluidic chambers filled with&#160;H2O2/H2O solution (0.01%-0.5%) or methanol solutions using pulsed UV laser of a relative low pulse fluence.

Area selettiva Modifica della Silicon bagnabilità della superficie da impulsi laser UV irradiazione in ambiente liquido

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of ...

Determining the Chemical Composition of Corrosion Inhibitor/Metal Interfaces with XPS: Minimizing Post Immersion Oxidation

An approach for acquiring more reliable X-ray photoelectron spectroscopy data from corrosion inhibitor/metal interfaces is described. More specifically, the focus is on metallic substrates immersed in acidic solutions containing organic corrosion inhibitors, as these systems can be particularly sensitive to oxidation following removal from solution. To minimize the likelihood of such degradation, samples are removed from solution within a glove box purged with inert gas, either N2 or Ar. The glove box is directly attached to the load-lock of the ultra-high vacuum X-ray photoelectron spectroscopy instrument, avoiding any exposure to the ambient laboratory atmosphere, and thus reducing the possibility of post immersion substrate oxidation. On this basis, one can be more certain that the X-ray photoelectron spectroscopy features observed are likely to be representative of the in situ submerged scenario, e.g. the oxidation state of the metal is not modified.

A protocol to avoid the oxidation of metallic substrates during sample transfer from an inhibited acidic solution to an X-ray photoelectron spectrometer is presented.

Determinare la composizione chimica di inibitore di corrosione Interfacce / metallo con XPS: Minimizzare post immersione Ossidazione

An approach for acquiring more reliable X-ray photoelectron spectroscopy data from corrosion inhibitor/metal interfaces is described. More specifically, ...

Chimica

Aerosol-assisted Chemical Vapor Deposition of Metal Oxide Structures: Zinc Oxide Rods

Whilst columnar zinc oxide (ZnO) structures in the form of rods or wires have been synthesized previously by different liquid- or vapor-phase routes, their high cost production and/or incompatibility with microfabrication technologies, due to the use of pre-deposited catalyst-seeds and/or high processing temperatures exceeding 900 &#176;C, represent a drawback for a widespread use of these methods. Here, however, we report the synthesis of ZnO rods via a non-catalyzed vapor-solid mechanism enabled by using an aerosol-assisted chemical vapor deposition (CVD) method at 400 &#176;C with zinc chloride (ZnCl2) as the precursor and ethanol as the carrier solvent. This method provides both single-step formation of ZnO rods and the possibility of their direct integration with various substrate types, including silicon, silicon-based micromachined platforms, quartz, or high heat resistant polymers. This potentially facilitates the use of this method at a large-scale, due to its compatibility with state-of-the-art microfabrication processes for device manufacture. This report also describes the properties of these structures (e.g., morphology, crystalline phase, optical band gap, chemical composition, electrical resistance) and validates its gas sensing functionality towards carbon monoxide.

Columnar zinc oxide structures in the form of rods are synthesized via aerosol-assisted chemical vapor deposition without the use of pre-deposited catalyst-seed particles. This method is scalable and compatible with various substrates based on either silicon, quartz or polymers.

Aerosol-assisted Chemical Vapor Deposition di strutture in ossido di metallo: aste di ossido di zinco

Whilst columnar zinc oxide (ZnO) structures in the form of rods or wires have been synthesized previously by different liquid- or vapor-phase routes, ...

Preparation and High-temperature Anti-adhesion Behavior of a Slippery Surface on Stainless Steel

Anti-adhesion surfaces with high-temperature resistance have a wide application potential in electrosurgical instruments, engines, and pipelines. A typical anti-wetting superhydrophobic surface easily fails when exposed to a high-temperature liquid. Recently, Nepenthes-inspired slippery surfaces demonstrated a new way to solve the adhesion problem. A lubricant layer on the slippery surface can act as a barrier between the repelled materials and the surface structure. However, the slippery surfaces in previous studies rarely showed high-temperature resistance. Here, we describe a protocol for the preparation of slippery surfaces with high-temperature resistance. A photolithography-assisted method was used to fabricate pillar structures on stainless steel. By functionalizing the surface with saline, a slippery surface was prepared by adding silicone oil. The prepared slippery surface maintained the anti-wetting property for water, even when the surface was heated to 300 &#176;C. Also, the slippery surface exhibited great anti-adhesion effects on soft tissues at high temperatures. This type of slippery surface on stainless steel has applications in medical devices, mechanical equipment, etc.

Slippery surfaces provide a new way to solve the adhesion problem. This protocol describes how to fabricate slippery surfaces at high temperatures. The results demonstrate that the slippery surfaces showed anti-wetting for liquids and a remarkable anti-adhesion effect on soft tissues at high temperatures.

Comportamento di anti-adesione preparazione e ad alta temperatura di una superficie scivolosa su acciaio inossidabile

Anti-adhesion surfaces with high-temperature resistance have a wide application potential in electrosurgical instruments, engines, and pipelines. A ...

Simultaneous Multi-surface Anodizations and Stair-like Reverse Biases Detachment of Anodic Aluminum Oxides in Sulfuric and Oxalic Acid Electrolyte

After reporting on the two-step anodization, nanoporous anodic aluminum oxides (AAOs) have been widely utilized in the versatile fields of fundamental sciences and industrial applications owing to their periodic arrangement of nanopores with relatively high aspect ratio. However, the techniques reported so far, which could be only valid for mono-surface anodization, show critical disadvantages, i.e., time-consuming as well as complicated procedures, requiring toxic chemicals, and wasting valuable natural resources. In this paper, we demonstrate a facile, efficient, and environmentally clean method to fabricate nanoporous AAOs in sulfuric and oxalic acid electrolytes, which can overcome the limitations that result from conventional AAO fabricating methods. First, plural AAOs are produced at one time through simultaneous multi-surfaces anodization (SMSA), indicating mass-producibility of the AAOs with comparable qualities. Second, those AAOs can be separated from the aluminum (Al) substrate by applying stair-like reverse biases (SRBs) in the same electrolyte used for the SMSAs, implying simplicity and green technological characteristics. Finally, a unit sequence consisting of the SMSAs sequentially combined with SRBs-based detachment can be applied repeatedly to the same Al substrate, which reinforces the advantages of this strategy and also guarantees the efficient usage of natural resources.

A protocol for fabricating nanoporous anodic aluminum oxides via simultaneous multi-surfaces anodization followed by stair-like reverse biases detachments is presented. It can be applied repeatedly to the same aluminum substrate, exhibiting a facile, high-yield, and environmentally clean strategy.

Anodizations multi-superficie simultanea e pregiudizi inversa scala-come distaccamento di ossidi di alluminio anodico in solforico e acido ossalico elettrolita

After reporting on the two-step anodization, nanoporous anodic aluminum oxides (AAOs) have been widely utilized in the versatile fields of fundamental ...

Fabrication of Superhydrophobic Metal Surfaces for Anti-Icing Applications

Several ways to produce superhydrophobic metal surfaces are presented in this work. Aluminum was chosen as the metal substrate due to its wide use in industry. The wettability of the produced surface was analyzed by bouncing drop experiments and the topography was analyzed by confocal microscopy. In addition, we show various methodologies to measure its durability and anti-icing properties. Superhydrophobic surfaces hold a special texture that must be preserved to keep their water-repellency. To fabricate durable surfaces, we followed two strategies to incorporate a resistant texture. The first strategy is a direct incorporation of roughness to the metal substrate by acid etching. After this surface texturization, the surface energy was decreased by silanization or fluoropolymer deposition. The second strategy is the growth of a ceria layer (after surface texturization) that should enhance the surface hardness and corrosion resistance. The surface energy was decreased with a stearic acid film.
The durability of the superhydrophobic surfaces was examined by a particle impact test, mechanical wear by lateral abrasion, and UV-ozone resistance. The anti-icing properties were explored by studying the ability to repeal subcooled water, freezing delay, and ice adhesion.

We illustrate several methodologies to produce superhydrophobic metal surfaces and to explore their durability and anti-icing properties.

Fabbricazione di superfici superidrofobiche metalliche per applicazioni Anti-Icing

Several ways to produce superhydrophobic metal surfaces are presented in this work. Aluminum was chosen as the metal substrate due to its wide use in ...

Metal-Assisted Electrochemical Nanoimprinting of Porous and Solid Silicon Wafers

Metal-assisted electrochemical imprinting (Mac-Imprint) is a combination of metal-assisted chemical etching (MACE) and nanoimprint lithography that is capable of direct patterning 3D micro- and nanoscale features in monocrystalline group IV (e.g., Si) and III-V (e.g., GaAs) semiconductors without the need of sacrificial templates and lithographical steps. During this process, a reusable stamp coated with a noble metal catalyst is brought in contact with a Si wafer in the presence of a hydrofluoric acid (HF) and hydrogen peroxide (H2O2) mixture, which leads to the selective etching of Si at the metal-semiconductor contact interface. In this protocol, we discuss the stamp and substrate preparation methods applied in two Mac-Imprint configurations: (1) Porous Si Mac-Imprint with a solid catalyst; and (2) Solid Si Mac-Imprint with a porous catalyst. This process is high throughput and is capable of centimeter-scale parallel patterning with sub-20 nm resolution. It also provides low defect density and large area patterning in a single operation and bypasses the need for dry etching such as deep reactive ion etching (DRIE).

A protocol for metal-assisted chemical imprinting of 3D microscale features with sub-20 nm shape accuracy into solid and porous silicon wafers is presented.

Nanoimprinting elettrochimico assistito da metalli di wafer di silicio poroso e solido

Metal-assisted electrochemical imprinting (Mac-Imprint) is a combination of metal-assisted chemical etching (MACE) and nanoimprint lithography that is ...

Metal Oxide Heterojunction for Photocatalytic Activities

There is a significant global demand for improvements in synthesis techniques and their optimal characteristics, especially for industrial-scale applications. Sol-gel-based solution combustion synthesis (SG-SCS) is a simple method to produce ordered porous materials. In this regard, Pearson&#39;s hard and soft acids and bases theory assists in selecting host-dopant reactivity to form a proper heterojunction.
The formation of a heterojunction also changes the essential properties of the materials, improving photocatalysis via charge transfer or synergistic activities. A calcination temperature of 500 &#176;C is ideal for this process based on the results of the stability assessment via a differential thermogravimetry ratio analysis (DTG).
The nanoscale dimensions of the nanoparticles (NPs) and nanocomposites (NCs) generated were validated using X-ray diffraction and high-resolution transmission electron microscopy (HRTEM). Furthermore, the scanning electron microscopy micrographs and BET analyses confirmed the porosity nature of the materials. HRTEM, X-ray photoelectron spectroscopy, and energy-dispersive X-ray investigations established the materials composition. The study found that NCs degraded the acid orange 8 (AO8) color more efficiently than bare ZnO.

The development of a heterojunction boosts the photocatalytic activities of solution combustion synthesis, which is a time-/energy-efficient process. Advanced analytical characterization techniques were used in this protocol to evaluate the materials&#39; characteristics, and nanocomposites demonstrated improved acid orange-8 dye degradation.