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.

電解液中の液体金属の界面張力の1.操作<ol><li>酸化<ol><li>ペトリ皿に（酸性または塩基性）水性電解質を注ぎます。酸化物が完全に除去されたことを確認するために、0.1 M 24よりも高い濃度（例えば、1M NaOHまたは1MのHCl）で、酸または塩基を使用しています。約1〜3ミリメートルの深さに料理を記入しますボリュームを使用してください。これらのソリューションで皮膚を触れないようにしてください。 </li><li>電解液中のガリウム系合金の（最適10-500μlの間）のドロップを配置するために、注射器を使用してください。例としては、共晶ガリウムインジウム（EGaIn）またはガリウムインジウムスズ（ガリンスタン）が挙げられます。純粋なガリウムを使用する場合は、凍結を防ぐために少なくとも30℃の電解液を暖めます。 </li><li>作用電極を確立するために、液体金属に銅線を配置します。液滴の直径よりも小さい直径を有する銅線を使用して、Eに、製造者の指示に従って、デジタルマルチメータを使用してワイヤは&lt;1Ωの抵抗を有するnsure。酸または塩基では、液体金属は、銅を濡らし、それによって、優れた電気的接触を形成します。 </li><li>溶液中ではなく、液体金属と接触して導通し、対向電極（例えば、銅、グラファイト、白金、）を配置します。対向電極は、&lt;1Ωの抵抗を持っている場合は、その寸法は無関係です。 </li><li>電圧源に配線を接続し、液体金属に正の電位を印加します。小さな形状変形のために、正の電圧適用&lt;大きな形状変形（と対向電極に向けて液体金属の移動）のために1 Vを、適用&gt; 1 Vを 注：溶液の濃度と対向電極からの落下の距離は、電気化学的な表面酸化の速度は、電解質によって、酸化物溶解速度と競合するので、界面張力の変化を誘発するのに必要な電圧を決定します。 </li></ol></lI&gt; <li>削減<ol><li>空のペトリ皿に、注射器から液体金属の滴（10〜500μl）を分注します。 </li><li>金属を水没レベルにペトリ皿に中立水電解液を注ぐ（ 例えば 、1Mのフッ化ナトリウム（NaFの）または1M塩化ナトリウム（NaCl）で）。 注意：酸性（pH &lt;3）または塩基性液（pH&gt; 10）の使用は、酸化物が自然に溶解するようになります。 </li><li>作用電極と、対向電極として機能するように、電解質への導線（例えば、銅）として機能するように液体金属に銅線を配置します。 </li><li>電圧源に配線を接続し、液体金属に負電位を印加します。約適用-1 V表面酸化物を除去し、金属基板からディウェッティングさせます。金属は、対向電極に最も近い側にディウェッティングする必要があります。 </li><li>完全に酸化物層を除去するために、より負の電位（&lt;-1 V）を適用します。 excesを適用することは避けてください、異常に大きい負の電圧が原因で、電解質の低下に液体金属上に表示された水素の気泡を防止します。 </li></ol></li></ol>無茎性飛沫を介した2表面張力測定<ol><li>レーザーカッターやフライス工具を使用して、ポリメチルメタクリレート（PMMA）（〜1mm厚）の作品の中心から端に直接パスをカットすべての方法PMMAの厚さを貫通してパスを切断しないでください。唯一の途中で約カット。この作品は、液体金属のための基質として機能します。例えば、ガラス、セラミックス、又はポリマーのような他の電気的に平坦な絶縁材料が、基板として機能することができます。 </li><li>同じツールを使用すると、PMMAの中心を通って1ミリメートル2穴をカット。 </li><li>ガイドとしてパスを使用して、PMMAの中央にさらさ先端のみで絶縁した銅線を実行します。それは、PMMA表面上に突出するように、ワイヤーの位置を調整します。漏れ防止接着剤で所定の位置にワイヤーをシール。カットただ、PMMAの表面上のワイヤは、それはあまりにも遠く（〜を超えて100μm）を拡張できないか、またはそれは、ドロップの形状を乱すます。 </li><li>鮮明な画像を得ることができるような透明な容器にテープPMMAピースダウン。 1 M NaOHでコンテナを記入し、突出した銅線の上に液体金属の25〜50μlのドロップを置きます。このワイヤは、作用電極として機能し、液滴を濡らします。 </li><li>白金メッシュ対電極と溶液中で飽和銀/塩化銀（Ag / AgCl）参照電極を置きます。ポテンショスタットに全ての電極を接続します。 </li><li>ドロップの表面形状がはっきりと見えるように、接触角ゴニオメータで容器を置きます。参照電極に対する電圧を制御し、形状、それにより液滴の界面張力を測定するために、ゴニオメーターを使用するポテンシオスタットを使用します。ゴニオメータは、液滴界面tensiを測定することが可能であることを確認してくださいに;これは、水平に取り付けられたカメラ 25から撮影した液滴イメージのカスタム軸対称形状解析を使用することも可能です。 </li></ol> 3.キャピラリーインジェクション<ol><li> 1MのNaOH溶液でガラスキャピラリーを記入してください。キャピラリー径は約1 mmでなければなりません。 </li><li>液体金属の液滴に対して毛細管フラッシュの一方の端を置きます。それがテーブル（重力すなわち 、垂直）の表面と平行になるように、キャピラリの位置を合わせます。液体金属滴と電解質を充填したキャピラリーとの間のエアギャップを避けてください。組立中に漏洩した可能性のある余分な電解質をオフに軽くたたく、ワイプの使用。 </li><li>キャピラリーの開放端部に液体金属で銅線（作用電極）と、導電性の対向電極（ 例えば銅線）を配置し、それに接触ソリューションように。 </li><li>電圧源に配線を接続し、液体金属に正の電位を印加します。液体金属は、cを充填開始する必要がありますapillary（対電極上の余分な泡の形成の原因となる大きな可能性を避けるため）。 </li></ol> 4.キャピラリー撤退<ol><li>ポリジメチルシロキサン（PDMS）からなるマイクロ流体チャネルを製造するために、ソフトリソグラフィ26とレプリカ成形技術を利用しています。 100μmの背の高い、および25〜65 mmの長さ、約100広い〜1000μmであるチャンネルを作ります。 チャンネルが100μm背の高いワイド千μmで、寸法、および65ミリメートル長いチャネルは、一貫性のある結果が得られたが、他でも動作する可能性があります注意してください。また、ガラスキャピラリー（ 例えば 、直径1mm、ホウケイ酸ガラス）の代わりに、PDMSマイクロチャネルを使用しています。 </li><li>液体金属を注入し、手動またはチャネルを完全に満たすために、シリンジポンプを使用して（ すなわち 、1000μmで、広い100μmの背の高い、と65ミリメートル長いチャネル用の6.5ミリメートル3）。 </li><li> 1 M NaOH又は1 M HCl中に浸漬した綿棒を使用して、リチウムの過剰量を除去しますそのようにチャネルの入口（及び、必要に応じて、コンセント）から頭の良い金属が、金属はPDMSの頂部表面と同一平面のままです。 </li><li>それは電解質ではなく、金属に触れる（例えば、銅、白金、またはタングステンのワイヤー）ようにアノードを電解質（例えば、1MのNaCl）でのチャネルの一方の端を水没し、配置します。 </li><li>液体金属自体が陰極として機能するように、チャネルのもう一方の端では、金属表面に別々の電極（例えば、Cu配線）に連絡してください。 </li><li>電圧源またはポテンショスタットにこれらのワイヤ（ すなわち 、アノードとカソード）を接続し、電気回路を完成。 3電極システムの場合は、それはほとんどの電解質の低下に水没するように、参照電極を配置します。 </li><li>還元電圧を印加する前に、実験を記録するために、三脚や顕微鏡でビデオカメラを取り付けます。焦点のすべてを取得するためにオートフォーカスモードを使用します。より良いコントロールの上に持ってマニュアルフォーカスを利用フィールド、ホワイトバランス、およびISOの深さ。必要に応じて、より高いFストップ（ すなわち 、11以上）、100分の1シャッター、オートホワイトバランス、オートISOを使用しています。 </li><li>実験の記録を開始します。マイクロチャネルから液体金属を回収するために約-1 Vを適用します。金属は、中性電解質中に移動を停止させるための電圧をオフにします。 </li></ol>

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The authors have nothing to disclose.

<html>この方法は、表面酸化物の堆積及び除去を駆動するために小さな電圧を使用ガリウム系液体金属の表面張力を制御します。メソッドは、電解質溶液中で動作しますが、それは単純で、異なる多種多様な状態で動作しますが、注目すべき微妙な点があります。電位の非存在下で、酸性および塩基性の両方の溶液は、酸化物27をエッチング 。酸化電位の印加は、酸性および塩基性の?...

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

界面張力を制御することは界面張力が支配的な力であるサブミリメートルの長さのスケールでの形状、位置、及び流体の流れを操作するための有効な方法です。この規模での水と有機液体の界面張力を制御するための様々な方法が存在します。しかし、これらの技術は、それらの大きな界面張力による液体金属の有用性が限られています。 液体金属は電気及び電磁機器で、柔らかい伸縮性、および再構成可能な形状の部品を形成することができます。それは機械的な方法（例えば、ポンプ）を介してこれらの流体を操作することが可能であるが、電気的な方法は、コントロールを小型化し、実装が容易です。しかし、ほとんどの電気技術は、独自の制約を持っている：オン誘電体エレクトロウェッティングは、ささやかな作動のための大規模な（キロボルト）電位、電気毛管現象は、界面張力の比較的小さな変化に影響を与えることができ、連続ELEが必要ですctrowettingは毛細血管内の液体金属のプラグに限定されています。 ここでは、電気化学的な表面反応を介して、ガリウムおよびガリウム系液体金属合金を作動させるための方法を提示します。迅速かつ可逆的に電解液中の液体金属の表面に電気化学ポテンシャルを制御すること（ゼロ近くまで̴500MN / m）の大きさの2以上のご注文によって界面張力を変化させます。さらに、この方法は、非常に控えめな電位（&lt;1 V）を必要と対向電極に対して印加されます。張力の結果として生じる変化は、主に界面活性剤として作用する表面酸化物層の電気化学的堆積によるものです。酸化物の除去は、界面張力、およびその逆を増加させます。この技術は、電解質の多種多様に適用され、それが置かれた基板とは無関係であることができます。

図 1Aは、酸化と還元のための単純な二電極法の一例を示す図です。この例では、液体金属の70μlの滴を1M NaOH溶液に接触して電気接続を確立するための銅線を入れました。 1 M NaOHが金属から表面酸化物を除去し、金属は、その界面張力までビーズにできます。ドロップ白金メッシュ対電極との間に2.5Vの電位を印加すると、液滴...

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

表面酸化と還元を経て液体金属の表面張力を操作する方法

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 ビュー.  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.

ビデオ: 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.

デジタルマイクロフルイディクスにBioanalytesの輸送を最適化するための縮小液滴表面相互作用の活用

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

工学

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.

液体金属電極中の超音波速度計測

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.

液体環境におけるパルスUVレーザー照射によるシリコン表面の濡れ性の選択エリア変更

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.

XPSで腐食防止剤/金属界面の化学組成を決定する：最小化後のイマージョン酸化

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

化学

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.

エアロゾルによる金属酸化物の構造の化学蒸着: 酸化亜鉛棒

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.

ステンレス鋼の滑りやすい表面の作製と高温の反付着挙動

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.

同時マルチ表面 Anodizations、階段のような逆バイアスで硫酸陽極酸化アルミニウムとシュウ酸電解質の剥離

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.

防氷用超撥水の金属表面の作製

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.

金属補導電気化学ナノインプリンティングの多孔質および固体シリコンウエハー

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.