Superhydrophobic membranes with electrically controllable permeability and their application to “smart” microbatteries

Lifton, Victor A.; Taylor, J. Ashley; Vyas, Bhavik B.; Kolodner, Paul; Cirelli, R.; Basavanhally, N.R.; Papazian, A.R.; Frahm, R.; Simon, Steve; Krupenkin, Tom N.

doi:10.1063/1.2965615

Cited by 39 publications

(27 citation statements)

References 18 publications

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“…The advantages of EWOD include low power consumption, large WCA change, and fast response. It is therefore promising for diverse applications, including lab-on-chips 4 , liquid lenses 5 , optical waveguides 6 , electronic displays 7 , 8 , microprism arrays 9 , and smart microbatteries 10 .…”

Section: Introductionmentioning

confidence: 99%

Electrowetting-on-dielectric characteristics of ZnO nanorods

Kim

Mirzaei

Kim

et al. 2020

Sci Rep

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Herein, we report the electrowetting-on-dielectric (eWoD) characteristics of Zno nanorods (nRs) prepared via the hydrothermal method with different initial Zn 2+ concentrations (0.03, 0.07, and 0.1 M). Diameter of the resultant ZnO NRs were 50, 70 and 85 nm, respectively. Contact angle (CA) measurements showed that the Teflon-coated ZnO NRs with diameters of 85 nm prepared from the 0.1 M solution had the highest CA (137°). During the EWOD studies, on the application of a voltage of 250 V, the water CA decreased to 78°, which demonstrates the potential application of this material in EWOD electronics. Furthermore, we explained the relationship between the applied voltage and CA based on the substrate nanostructures and our newly developed NR-on-film wetting model. In addition, we further validated our model by introducing the homo-composite dielectric structure, which is a composite of thin layered ZnO/Teflon and nano-roded ZnO/Teflon. Electrowetting (EW) is defined as the decrease in contact angle (CA) when a sufficiently large driving voltage is applied to the interface of solid/liquid. In direct EW, a voltage is used between a liquid and an electrode. Charges and dipoles redistribute at the interface between the liquid and solid, which changes the surface tension, leading to a decrease in the CA of the liquid droplets. However, direct EW can electrolyze the liquid before any change in the water contact angle (WCA), which limits its application 1. To overcome this issue, electrowetting-on-dielectric (EWOD) can be used. In this technique, a dielectric material is sandwiched between the liquid of interest and the underlying electrode (Fig. 1). EWOD is very effective for significantly changing the CA, because the dielectric layer effectively blocks the process of charge transfer at the liquid/electrode interface, which eliminates unwanted electrolysis 2. Therefore, EWOD is used to facilitate EW on solids, for practical applications. Although EWOD devices permit a large CA change, they generally need a high driving voltage. The dielectric layer blocks the transfer of electrons, while sustaining high voltage at the interface, which results in an electric double layer (EDL) formation in the presence of the applied voltage. When a hydrophobic dielectric material is used, the large initial WCA can result in a large change in the WCA 3. The advantages of EWOD include low power consumption, large WCA change, and fast response. It is therefore promising for diverse applications, including lab-on-chips 4 , liquid lenses 5 , optical waveguides 6 , electronic displays 7, 8 , microprism arrays 9 , and smart microbatteries 10. SiO 2 is a highly popular material for EWOD studies 11 because of its excellent compatibility with the microelectronic industry. In our previous study 12 , we investigated the EWOD properties of electrospray-deposited SiO 2 layers and found that the WCA of the optimal SiO 2 layer underwent a hydrophobic-to-hydrophilic transition under a driving voltage of 150 V in air. A novel EWOD mechanism, wherein the ...

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Section: Introductionmentioning

confidence: 99%

Electrowetting-on-dielectric characteristics of ZnO nanorods

Kim

Mirzaei

Kim

et al. 2020

Sci Rep

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“…It is well known that spreading of a droplet can be effectively controlled by electrowetting (EW), which can date back to the electrocapillarity discovered by Lippmann in 1875. 6 Since the 1990s, great developments have been made in EW, and nowadays these achievements can be seen in various fields such as displays, [7][8][9] optics (liquid lenses, [10][11][12] various beam steering devices, 13 reflectors), reserve batteries, 14,15 lab-on-a-chip systems, [16][17][18] and electronic papers. 19,20 Compared to other methods of controlling the droplet, such as dielectrophoresis (DEP), EW has the advantages of easy operation, sensitive response, and electrical reversibility.…”

Section: Introductionmentioning

confidence: 99%

Wetting and electrowetting on corrugated substrates

Wang

Zhao

2017

Physics of Fluids

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Wetting and electrowetting (EW) on corrugated substrates are studied experimentally and theoretically in this paper. On corrugated substrates, because of the anisotropy of surface morphology, the droplet shows an elliptical shape and the spreading velocities in different directions are different. Spreading of a droplet is usually controlled not only by the surface tensions but also by hemi-wicking. Our experimental results indicated that liquids along the grooves propagate much faster than those in the direction vertical to the grooves. However, spreading in both directions obeys the same scaling law of l ∼ t 4/5. EW on corrugated substrates reveals some differences with that on smooth surfaces. The change of contact angles with an applied voltage follows a linear relationship in two stages instead of the smooth curve on flat surfaces. There exists a critical voltage which divides the two stages. The transition of a droplet from the Cassie state to the Wenzel state on corrugated substrates was also discussed. The extended EW equation was derived with the free energy minimization approach, and the anisotropic factor was introduced. From the extended equation, it is found that EW is affected by the anisotropic factor significantly. For the smooth surfaces, the extended EW equation will degenerate to the classical Lippmann-Young equation. Our research may help us to understand the wetting and EW of droplets on corrugated substrates and assist in their design for practical applications.

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“…Intensive research efforts are currently focused on the fabrication of functional ''smart" surfaces with reversibly switchable wettability, especially switching between superhydrophilicity (contact angle (CA) less than 5°) and superhydrophobicity (CA higher than 150°), due to their significance in both fundamental researches and practical applications, such as in drug delivery, microfluidic devices, intelligent membranes, and lab-on-chip systems [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. One typical strategy for obtaining reversible switching of surface wettability is to change the surface conformation and/or morphology of stimuli-sensitive materials via appropriate external stimuli, such as light illumination [14,19], electrical potential [17], temperature [8], and pH [13].…”

Section: Introductionmentioning

confidence: 99%

A strategy of fast reversible wettability changes of WO3 surfaces between superhydrophilicity and superhydrophobicity

Zhang

2010

Journal of Colloid and Interface Science

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Superhydrophobic membranes with electrically controllable permeability and their application to “smart” microbatteries

Cited by 39 publications

References 18 publications

Electrowetting-on-dielectric characteristics of ZnO nanorods

Electrowetting-on-dielectric characteristics of ZnO nanorods

Wetting and electrowetting on corrugated substrates

A strategy of fast reversible wettability changes of WO3 surfaces between superhydrophilicity and superhydrophobicity

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