The Electrocapillary Electrowetting Behaviors Of Liquid Ga-In And Wood Alloys In NaOH Aqueous Solution

This paper has studied the electric capillary action of liquid metal under the electric field in NaOH aqueous solution,which will use the function of electric field force to drive the liquid metal and discuss the discipline between environment variables and electrical capillary action of liquid metal.The results of research would provide a certain theoretical basis and technical support about control system part of microelectromechanical.In the experiment,the materials that liquid Wood alloy and Ga-In alloy are used and the graphite electrodes are used into experimental process to apply electric field,The phenomenons of research about liquid metal in NaOH aqueous solution that including the following processes,such as surface tension,interfacial electrochemistry reaction,the generation of oxidation film,electrowetting and dynamic processes of electric capillarity.When the electrode configuration?the gap of two electrode is 4cm?is that the anode connects to the liquid metal and the cathode accesses solution,no matter what kind of metals and any value of voltages are adopted,the anode are oxidized and the water is electrolyzed and produces O₂,the cathodic reduction reaction,then the water is electrolyzed and produce H₂.When Ga-In alloy is oxidized,the oxide film would be produced and the main compositions are Ga₂O₃ and In2O3 after oxidation,it reacts with NaOH solution and produces GaO₂-and InO₂-,these ions have changed the color of the solution.the white gel copolymer in the solution is Ga₂O₃-Ga?OH?3.The surface of the Ga-In alloy metal droplet under the voltage of 5V(0.10mol·L^-1 NaOH aqueous solution)gradually generates oxide film through oxidation,as the voltage increasing continuously,its surfactant can make the surface tension of the droplet shift between 679⁴00 mN/m.The wood alloy is oxidized to produce components which including CdO? SnO₂? Bi₂O₃?PbO₂ oxide film,it reacts with NaOH solution would produce Sn?OH?62-?SnO₃^2-?SnO₂²?PbO₃^2-?Cd?OH?₄^2-,these ions have changed the color of the solution,the white floc in the solution is Bi₂O₃-Bi?OH?₃.it would produce the black substance in the solution if one applied excessive voltage,the oxide film could be CdO.The surface of wood alloy droplet can be gradually generated oxide film through oxidation reaction under 5V voltage(0.10mol·L^-1 NaOH aqueous solution),as the voltage increasing continuously,it can be surfactant and makes the surface tension of the droplet from shift between 295⁴5 mN/m.When changing electrode configuration?the gap two electrode is 4 cm?and accessing cathode to the liquid metal and anode accesses solution,the electric capillarity that induced by electrode from reduction reaction,which can make two kinds of metal oxide about the droplet film rupture and elongated,partial oxidation membrane would dissolve in the solution.The oxide film of Ga-In alloy droplet would return to original state in 10 seconds,The oxide film of Wood alloy droplet would return to original state in 3 seconds,the surface tension of both types of alloy droplets would increase rapidly to the initial value.When the electrode configuration?the gap of two electrode is 10cm?is both the cathode and anode accesses solution,which making the droplets beside cathode extreme,and then making it move to the anode by the electric field force.Besides,we should measure the relationship among maximum spreading process of the droplet,speed and the quality of voltage,concentration.The results have showed that Ga-In alloy and Wood alloy metal droplet would occurred the most obvious spread with the increasing concentration of NaOH and critical voltage,there is a saturation value respectively in 3.0 mol·L^-1 and 0.30 mol·L^-1.When voltage and quality are ceitainly,the solution concentration of driving Ga-In alloy will be more than wood alloy,the movement process of wood not only is more sensitive to the concentration of alloy but also the activity is low and the loss is less in the experiment,the material is more cheap,too.