An optofluidic tunable Fresnel lens for spatial focal control based on electrowetting-on-dielectric (EWOD)

Clement, Carlos Enrico; Thio, Si Kuan; Park, Sung-Yong

doi:10.1016/j.snb.2016.08.125

Cited by 58 publications

(38 citation statements)

References 28 publications

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“…Figure 10d–f show the versatility of our prism arrays that are formed with the apex angles, ranging −20° ≤ ϕ ≤ 20° by varying the applied voltages at each of the prism sidewalls. By using two liquids with different refractive indices ( n air ≠ n 1 ≠ n 2 ), the previous studies have demonstrated beam steering of the incoming light that can be effectively achieved without the need of bulky mechanical moving parts [22,23,24]. Figure 11a shows an experimental demonstration of beam steering using a single liquid prism filled with high-reflective-index oil 1-bromonapthalene (liquid 1) and water (liquid 2).…”

Section: Resultsmentioning

confidence: 99%

“…Bias voltages (V L and V R ) are subsequently applied to the left and right sidewalls to induce the electrowetting effect to essentially control the prism apex angle ( ϕ ) [19,21,22]. In several previous studies, beam steering performance achieved by a single prism has been well described as a function of the refractive indices ( n 1 ≠ n 2 ) of each medium as well as the apex angle ( ϕ ) [22,23,24]. Our group recently achieved the highest beam steering angle ever demonstrated up to β = 19.06° using a double-stacked prism configuration [22].…”

Section: Ion Gel Layer Coating For 3d Ewod Device Fabricationmentioning

confidence: 99%

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A Study of Dip-Coatable, High-Capacitance Ion Gel Dielectrics for 3D EWOD Device Fabrication

et al. 2017

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We present a dip-coatable, high-capacitance ion gel dielectric for scalable fabrication of three-dimensional (3D) electrowetting-on-dielectric (EWOD) devices such as an n × n liquid prism array. Due to the formation of a nanometer-thick electric double layer (EDL) capacitor, an ion gel dielectric offers two to three orders higher specific capacitance (c ≈ 10 μF/cm2) than that of conventional dielectrics such as SiO2. However, the previous spin-coating method used for gel layer deposition poses several issues for 3D EWOD device fabrication, particularly when assembling multiple modules. Not only does the spin-coating process require multiple repetitions per module, but the ion gel layer also comes in risks of damage or contamination due to handling errors caused during assembly. In addition, it was observed that the chemical formulation previously used for the spin-coating method causes the surface defects on the dip-coated gel layers and thus leads to poor EWOD performance. In this paper, we alternatively propose a dip-coating method with modified gel solutions to obtain defect-free, functional ion gel layers without the issues arising from the spin-coating method for 3D device fabrication. A dip-coating approach offers a single-step coating solution with the benefits of simplicity, scalability, and high throughput for deposition of high-capacitance gel layers on non-planar EWOD devices. An ion gel solution was prepared by combining the [EMIM][TFSI] ionic liquid and the [P(VDF-HFP)] copolymer at various wt % ratios in acetone solvent. Experimental studies were conducted to fully understand the effects of chemical composition ratios in the gel solution and how varying thicknesses of ion gel and Teflon layers affects EWOD performance. The effectiveness and potentiality of dip-coatable gel layers for 3D EWOD devices have been demonstrated through fabricating 5 × 1 arrayed liquid prisms using a single-step dip-coating method. Each prism module has been individually controlled to achieve spatial beam steering without the need for bulky mechanical moving parts.

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Section: Resultsmentioning

confidence: 99%

Section: Ion Gel Layer Coating For 3d Ewod Device Fabricationmentioning

confidence: 99%

A Study of Dip-Coatable, High-Capacitance Ion Gel Dielectrics for 3D EWOD Device Fabrication

et al. 2017

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“…Electrowetting (EW) refers to the phenomenon of altering the surface wettability of an electrode or dielectric layer with an applied electric field [1,2]. As an approach to manipulating minute fluids, electrowetting has attracted a great deal of attention for its application within reflective display devices [3,4], lab-on-a-chip systems [5,6], and optic lenses [7,8]. The basis of modern electrowetting was first described in detail by G. Lippmann in 1875 [9].…”

Section: Introductionmentioning

confidence: 99%

Bifunction-Integrated Dielectric Nanolayers of Fluoropolymers with Electrowetting Effects

Umar

et al. 2018

Materials

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Fluoropolymers play an essential role in electrowetting (EW) systems. However, no fluoropolymer possesses the desirable properties of both hydrophobicity and dielectric strength. In this study, for the first time, we report the integration of two representative fluoropolymers—namely, Teflon AF (AF 1600X) and Cytop (Cytop 809A)—into one bifunctionalized dielectric nanolayer. Within this nanolayer, both the superior hydrophobicity of Teflon AF and the excellent dielectric strength of Cytop were able to be retained. Each composed of a 0.5 μm Cytop bottom layer and a 0.06 μm Teflon AF top layer, the fabricated composite nanolayers showed a high withstand voltage of ~70 V (a dielectric strength of 125 V/μm) and a high water contact angle of ~120°. The electrowetting and dielectric properties of various film thicknesses were also systemically investigated. Through detailed study, it was observed that the thicker Teflon AF top layers produced no obvious enhancement of the Cytop/Teflon AF stack.

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“…In addition, direct manipulation of discrete droplets enables fabrication and operation of highly automated microfluidics systems with more flexibility and higher efficiency [6][7][8][9][10][11][12]. Due to these unique advantages, EWOD digital microfluidics has been used for tremendous applications such as medical [13][14][15][16][17][18][19], display [20,21], optics [22,23], and cooling [24,25]. In addition, there are many recent EWOD studies on engineering applications such as optofluidics and solar energy [26,27].…”

Section: Introductionmentioning

confidence: 99%

Accurate, consistent, and fast droplet splitting and dispensing in electrowetting on dielectric digital microfluidics

Nikapitiya

Nahar

Moon

2017

Micro and Nano Syst Lett

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This letter reports two novel electrode design considerations to satisfy two very important aspects of EWOD operation-(1) Highly consistent volume of generated droplets and (2) Highly improved accuracy in the generated droplet volume. Considering the design principles investigated two novel designs were proposed; L-junction electrode design to offer high throughput droplet generation and Y-junction electrode design to split a droplet very fast while maintaining equal volume of each part. Devices of novel designs were fabricated and tested, and the results are compared with those of conventional approach. It is demonstrated that inaccuracy and inconsistency of droplet volume dispensed in the device with novel electrode designs are as low as 0.17 and 0.10%, respectively, while those of conventional approach are 25 and 0.76%, respectively. The dispensing frequency is enhanced from 4 to 9 Hz by using the novel design.

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An optofluidic tunable Fresnel lens for spatial focal control based on electrowetting-on-dielectric (EWOD)

Cited by 58 publications

References 28 publications

A Study of Dip-Coatable, High-Capacitance Ion Gel Dielectrics for 3D EWOD Device Fabrication

A Study of Dip-Coatable, High-Capacitance Ion Gel Dielectrics for 3D EWOD Device Fabrication

Bifunction-Integrated Dielectric Nanolayers of Fluoropolymers with Electrowetting Effects

Accurate, consistent, and fast droplet splitting and dispensing in electrowetting on dielectric digital microfluidics

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