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. 2019 Sep 10;9(1):13062.
doi: 10.1038/s41598-019-49560-9.

Optofluidic lens based on electrowetting liquid piston

Lin-Yang Li  1 , Rong-Ying Yuan  1 , Jin-Hui Wang  1 , Lei Li  2 , Qiong-Hua Wang  3
Affiliations

Optofluidic lens based on electrowetting liquid piston

Lin-Yang Li et al. Sci Rep. .

Abstract

The conventional electrowetting lens usually has one tunable liquid-liquid (L-L) interface. The shape of L-L interface is deformed to get variable focal length due to electrowetting effect. However, contact angle saturation of the L-L interface is an unavoidable problem which prevents focal length from further changing. Here, we demonstrate an optofluidic lens based on electrowetting liquid piston. The proposed lens has two connected chambers, the piston chamber and the lens chamber to form a closed-loop fluidic system. The electrowetting liquid piston can generate clockwise and counter-clockwise liquid flows, which can make the L-L interface convex and concave. To prove the concept, we fabricate an optofluidic device whose shortest negative and positive focal lengths are ~-17.9 mm and ~18 mm with 5 mm aperture, respectively. The proposed optofluidic lens has large tunable focal length range. Widespread application of such an adaptive lens is foreseeable.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1
Schematic cross-sectional structure and the principle of changing the focal length: (a) Cell structure. (b) Initial equilibrium state. (c) The equilibrium state when an extra voltage (U1) is applied to form a positive lens. (d) The equilibrium state when an extra voltage (U2) is applied to form a negative lens.
Figure 2
Figure 2
Operating process of the proposed lens. (a) The equilibrium state when an extra voltage (U1) is applied to the upper electrode. (b) The equilibrium state when an extra voltage (U2) is applied to the lower electrode. (c) Deformation of L-L interface with different voltages (Video 1).
Figure 3
Figure 3
Fabricated prototype of optofluidic lens based on electrowetting piston. (a) All the elements of the device. (b) Assembled prototype.
Figure 4
Figure 4
The focal length of the optofluidic lens changes at different voltages. (a) Changes in focal length when different voltages are applied to the upper electrode. (b) Changes in focal length when different voltages are applied to the lower electrode (Video 2).
Figure 5
Figure 5
Focal length measurement of the optofluidic lens. (a) Schematic diagram of experimental device. (b) An experimental device for measuring positive lenses. (c) An experimental device for measuring negative lenses.
Figure 6
Figure 6
Variation of focal length with voltage. (a) Positive focal length changes with the voltage. (b) Negative focal length changes with the voltage.
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