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.

전해질 액체 금속의 계면 장력의 조작 1. <ol><li> 산화 <ol><li> 페트리 접시에 (산성 또는 염기성) 수성 전해질을 따르십시오. 산화물이 완전히 제거되었는지 확인하기 위해,보다 큰 농도 0.1 M (24) (예를 들어 1 M의 NaOH 또는 1 M 염산)과 산 또는 염기를 사용한다. 약 1-3mm의 깊이에 접시를 채울 것입니다 볼륨을 사용합니다. 이러한 솔루션으로 피부에 접촉하지 마십시오. </li><li> 전해질 중의 갈륨 계 합금의 (최적 10-500 μL 사이) 방울을 배치하는 주사기를 사용한다. 예로는 공융 갈륨 인듐 (EGaIn) 또는 갈륨 인듐 주석 (Galinstan)를 포함한다. 순수한 갈륨을 사용하는 경우, 동결 방지 적어도 30 ° C로 가온 전해질. </li><li> 작동 전극을 확립 액체 금속으로 구리 와이어를 배치했다. 강하보다 작은 직경을 갖는 구리 와이어를 사용하여, 전자를 제조업체의 지시에 따라, 디지털 멀티 미터를 사용하여와이어가 &lt;1 Ω의 저항이 nsure. 산 또는 염기에서, 액체 금속은 구리를 습윤시켜 우수한 전기적 접촉을 형성 할 것이다. </li><li> 용액 중에서 실시하는 대향 전극 (예를 들어 구리, 흑연, 백금 등)을 배치 할 수 있지만 액체 금속과 접촉한다. 대향 전극은 &lt;1 Ω의 저항을 갖는 경우, 그 치수는 부적합하다. </li><li> 전압 소스에 전선을 연결하고 액체 금속에 긍정적 인 가능성을 적용합니다. 작은 모양 변형의 경우, 긍정적 인 전압 적용 1 (V) &lt;큰 모양 변형 (카운터 전극을 향해 액체 금속의 이동)에 대한 1 V.를 적용&gt;을 주 : 용액의 농도와 대향 전극으로부터 강하 거리가 전기 화학적 표면 산화의 속도는 전해질에 의해 산화 분해 속도와 경쟁 때문에 계면 장력의 변화를 유도하는 데 필요한 전압을 지시. </li></ol></lI&gt; <li> 절감 <ol><li> 비어있는 페트리 접시에 주사기로부터 액체 금속 방울 (10-500 μL)을 분배. </li><li> 금속 잠기 레벨 페트리 접시에 중성 수성 전해질을 붓고 (예를 들어 1 M 불화 나트륨 (NaF로부터) 또는 1 M 염화나트륨). 참고 : 산성 (PH &lt;3) 또는 염기성 용액 (PH&gt; 10)의 사용은 산화물이 자발적으로 용해의 원인이됩니다. </li><li> 작업 전극 및 카운터 전극으로서 작용하는 전해질에 도선 (예를 들어, 구리)로 작동하도록 액체 금속으로 구리 와이어를 배치했다. </li><li> 전압 소스에 전선을 연결하고 액체 금속에 부정적인 잠재력을 적용합니다. 표면 산화물을 제거하고, 금속 기판으로부터 디 웨팅 (dewet)하게하는데 약 -1 V를 적용. 금속 반 전극 측에 가장 가까운에 디 웨팅 (dewet)해야한다. </li><li> 완전히 산화물 층을 제거하기 위해 더 음 전위 (&lt;-1 V)를 적용한다. exces을 가하지 마십시오sively 큰 음 전압 때문에 전해액의 감소에 액체 금속에 게재 수소 기포를 방지 할 수있다. </li></ol></li></ol> 을 Sessile 물방울를 통해 2. 표면 장력 측정 <ol><li> 레이저 커터 또는 밀링 공구를 사용하여, 폴리 메틸 메타 크릴 레이트 (PMMA) (~ 1mm 두께)의 부재의 중앙으로부터 에지까지 직접 경로를 차단하는 모든 방법 PMMA의 두께를 통해 경로를 차단하지 않는다.; 단지 중간을 통해 약 잘라. 이 작품은 액체 금속 기판이 될 것입니다. 다른 평면과 전기 절연성 유리, 세라믹 등의 재료, 또는 중합체는 또한 기판으로서 역할을 할 수있다. </li><li> 같은 도구를, PMMA의 중심을 1mm 2 구멍을 잘라. </li><li> 참조 경로를 이용하여, PMMA의 중심부에 노출 만 팁 절연 구리선을 실행. 그것은 PMMA 표면 위에 돌출되도록 와이어를 배치. 누액 방지 접착제 대신에 와이어를 밀봉합니다. 절단다만 PMMA의 표면 위에 와이어하지만 너무 (이후 ~ 100 ㎛)를 확장 할 수 없거나 그 방울의 형상을 방해 할 것이다. </li><li> 테이프 선명한 화상을 얻을 수있는 투명 용기에 PMMA 편 다운. 1 M NaOH로 컨테이너를 작성하고, 돌출 된 구리 와이어에 액체 금속의 25-50 μL 드롭 놓습니다. 이 와이어는 작동 전극의 역할을하고 물방울 젖은됩니다. </li><li> 백금 메쉬 카운터 전극과 용액에 포화은 / 염화은은 (Ag / AgCl을) 기준 전극을 배치합니다. 텐쇼에 전극을 모두 연결합니다. </li><li> 방울의 표면 형상이 명확하게 보이도록 접촉각 각도계에 컨테이너를 배치했다. 기준 전극에 대하여 전압을 제어하는​​ 포 텐쇼 스타트를 사용하여 형상 및 드롭함으로써 계면 장력을 측정하는 측각기를 사용한다. 고니 오 미터가 측정 고착 드롭 계면 tensi 할 수 있는지 확인에; 이것은 수평으로 장착 카메라 (25)에서 촬영 화상의 드롭 맞춤 축 대칭 형상 분석을 사용하는 것도 가능하다. </li></ol> 3. 모세관 주입 <ol><li> 1 M의 NaOH 용액으로 유리 모세관을 입력합니다. 모세관의 직경은 ~ 1mm이어야한다. </li><li> 액체 금속의 하락에 대한 모세관 높이의 한쪽 끝을 놓습니다. 이 테이블 (중력 즉, 수직)의 표면과 평행이되도록 모세관을 정렬. 액체 금속 드롭 및 전해질 채워진 모세관 사이의 에어 갭을 피하십시오. 이 닦아 조립시 누출 수있는 여분의 전해질을 가볍게 두 드리 사용. </li><li> 모세관의 개방 단부에 액체 금속에서 구리 와이어 (작용 극), 및 도전성 대향 전극 (예를 들면 구리선)을 놓고 접촉되도록 용액. </li><li> 전압 소스에 전선을 연결하고 액체 금속에 긍정적 인 가능성을 적용합니다. 액체 금속은 C를 충전 시작해야apillary (카운터 전극에 과도한 거품 형성의 원인이됩니다 큰 잠재력을 피하기). </li></ol> 4. 모세관 탈퇴 <ol><li> 폴리 디메틸 실록산 (PDMS)로 이루어지는 미세 유체 채널을 제작하는 소프트 리소그래피 (26) 및 복제 성형 기술을 이용한다. 100 μm의 높이 약 100 1,000 μm의 넓은 채널을 제작, 긴 25-65mm. 채널 100 μm의 키가 큰 폭 1,000 μm의, 치수, 65 mm 길이 채널은 일관된 결과를 생산하지만, 다른 사람도 작동 수 있습니다. 대안으로, 유리 모세관 (예를 들어, 1mm 직경, 붕규산 유리) 대신 PDMS 마이크로 채널을 사용한다. </li><li> 액체 금속을 주입하거나, 수동으로 채널을 완전히 채우기 위하여 주사기 펌프를 사용하여 (즉, 1,000 ㎛의, 폭 100 ㎛ 높이, 65 mm 길이 채널 6.5 mm 3). </li><li> 1 M 수산화 나트륨 또는 1 M 염산에 침지 한 면봉을 사용하여, 리튬의 과잉을 제거그래서 채널의 입구 (그리고, 필요한 경우, 출구)에서 파운드 금속, 금속 PDMS의 상면과 같은 높이로 남아. </li><li> 이 전해질 아니라 금속 접촉 (예를 들면, 구리, 백금, 텅스텐 또는 와이어)되도록 애노드 전해질 (예를 들면, 1 M의 NaCl)에있는 채널의 일단 잠수함 및 배치. </li><li> 액체 금속 자체가 캐소드로서 작용하도록 상기 채널의 타단에, 금속 표면에 별도의 전극 (예를 들면, 구리 배선)에 문의. </li><li> 전압 소스 또는 텐쇼 이러한 전선 (즉, 양극과 음극)을 연결하고 전기 회로를 완료합니다. 세 개의 전극 시스템의 경우, 거의 전해질의 드롭에 잠기면되도록 기준 전극을 배치했다. </li><li> 환원 전압을인가하기 전에, 실험을 기록 삼각대 또는 현미경에 비디오 카메라를 탑재. 초점에서 모든 것을 얻을 자동 초점 모드를 사용합니다. 더 나은 제어를 통해이 매뉴얼 포커스를 활용필드, 화이트 밸런스, ISO의 깊이. 필요에 높은 F 정지 (즉, 11 이상), 1/100 번째 셔터, 자동 화이트 밸런스 자동 ISO를 사용합니다. </li><li> 실험을 기록 시작합니다. 마이크로 채널에서 액체 금속을 회수하는 데 약 -1 V를 적용합니다. 중성 전해질 이동 중지 금속을 유발하는 전압의 전원을 끄십시오. </li></ol>

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M., Brown, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+oxidation+on+the+mechanical+properties+of+liquid+gallium+and+eutectic+gallium-indium.">Effect of oxidation on the mechanical properties of liquid gallium and eutectic gallium-indium.</a> Phys. Fluids. 24, 063101 (2012).</li><li>Rotenberg, Y., Boruvka, L., Neumann, A. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+surface+tension+and+contact+angle+from+the+shapes+of+axisymmetric+fluid+interfaces.">Determination of surface tension and contact angle from the shapes of axisymmetric fluid interfaces.</a> J. Colloid Interface Sci. 93, 169-183 (1983).</li><li>Xia, Y., Whitesides, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Soft+Lithography.">Soft Lithography.</a> Annu. Rev. Mater. Sci. 28 (1), 153-184 (1998).</li><li>Pourbaix, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Atlas of Electrochemical Equilibria in Aqueous Solutions. , (1974).</li><li>Gough, R. 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=Rapid+electrocapillary+deformation+of+liquid+metal+with+reversible+shape+retention.">Rapid electrocapillary deformation of liquid metal with reversible shape retention.</a> Micro Nano Syst. Lett. 3 (1), 1-9 (2015).</li><li>Wang, M., Trlica, C., Khan, M. R., Dickey, M. D., Adams, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+reconfigurable+liquid+metal+antenna+driven+by+electrochemically+controlled+capillarity.">A reconfigurable liquid metal antenna driven by electrochemically controlled capillarity.</a> J. Appl. Phys. 117 (19), 194901 (2015).</li></ol>

The authors have nothing to disclose.

<html> 이 방법은 표면 산화물의 증착 및 제거를 작은 구동 전압을 사용하여 갈륨 계 액체 금속의 표면 장력을 제어한다. 방법 만 전해질 용액에서 작동되지만,이 간단하고, 다른 다양한 조건에서 작동하지만, 주목할 미묘있다. 전위의 부재, 모두 산성 및 염기성 용액은 산화물 (27)을 에칭하여. 산화 전위의 적용은 산성 및 염기성 용액 모두를 포함하여 수성 전해질의 표면 산화물의 생성을 ?...

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

계면 장력을 제어하는​​ 계면 장력이 지배적 힘 서브 밀리미터 길이 스케일에서 유체의 형상, 위치 및 흐름을 조작하기위한 효과적인 방법이다. 다양한 방법이 규모 수성 및 유기 액체의 계면 장력을 제어하기 위해 존재한다; 그러나, 이러한 기술은 그들의 큰 계면 장력 액체 금속 용 유틸리티를 제한하고있다. 액체 금속은 전자 및 전자 장치에있어서, 부드러운 신축성 및 형상 재구성 컴포넌트를 형성 할 수있다. 그것이 기계적 방법 (예를 들어, 펌핑)을 통해 상기 유체를 조작하는 것이 가능하지만, 전자의 방법은, 소형화 제어 및 구현하기 쉽다. 그러나, 대부분의 전기 기술은 자신의 제약이있다 : - 온 - 유전체 일렉트로 겸손 작동을위한 대형 (kV의) 전위, electrocapillarity은, 계면 장력에 상대적으로 작은 변화에 영향을 미칠 수있는 지속적인 ELE이 필요합니다ctrowetting는 모세관 내의 액체 금속 플러그로 제한된다. 여기서, 우리는 전기 화학 반응을 통해 표면 갈륨 갈륨 계 액체 금속 합금을 작동시키기위한 방법을 제시한다. 가역적으로 빠르게 전해질에서 액체 금속의 표면에 전기 잠재력을 제어하고하면 (제로 근처에 ̴500 mN의 / M) 크기의이 원 이상 구매시에 의해 계면 장력을 변경합니다. 또한,이 방법은 대향 전극에 대하여인가 단지 아주 적당한 전위 (V 1은 &lt;)을 필요로한다. 장력의 변화의 결과는 주로 계면 활성제로서 작용하는 표면 산화물 층의 전기 화학 증착에 기인한다; 산화물의 제거는 계면 장력, 반대로 증가합니다. 이 기술은 전해액의 다양한 적용이 놓이는 기판과 무관 할 수있다.

도 1은 산화 및 환원에 대한 간단한 2 전극 기술의 예를 나타낸다. 이때, 1 M NaOH 용액 연락처에 구리선을 배치 액체 금속의 70 μL 강하의 전기적인 접속을 확립한다. 1 M NaOH를 인해 계면 장력까지 비드 금속을 금속의 표면 산화물을 제거하고 있습니다. 드롭 및 백금 메쉬 대향 전극 사이에 2.5 V 전위를인가하면, 드롭의 표면을 산화시?...

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

방법은 표면 산화와 환원을 통해 액체 금속의 표면 장력을 조작

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 조회수.  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.

비디오: 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.

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

연구

공학

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.

액체 금속 전극의 초음파 속도 측정

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.

액체 환경에서의 펄스 자외선 레이저 조사에 의한 실리콘 표면의 젖음성의 선택 영역 수정

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.

XPS와 부식 억제제 / 금속 인터페이스의 화학 성분을 결정 : 최소화 포스트 집중 산화

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

화학

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.

에 어로 졸 기반 구조 금속 산화물의 화학 증기 증 착: 산화 아연 막대

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.

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.

동시-표면 Anodizations와 황산에 양극 알루미늄 산화물 및 괭이밥에서 채취한 산 성 전해질의 계단 처럼 역방향 바이어스 분리

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.

반 장식 응용 프로그램 Superhydrophobic 금속 표면의 제조

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.

다공성 및 고체 실리콘 웨이퍼의 금속 보조 전기 화학 나노 임프린팅

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.