Research and application advances of photo-responsive droplet manipulation functional surface

Zhang Chen; Wen Tong; Liu Zezhi; Gao Wenping; Wang Xinkong; Li Ziyu; Kuang Cuifang; Wang Kaige; Bai Jintao

doi:10.12086/oee.2023.220326

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Zhang C, Wen T, Liu Z Z, et al. Research and application advances of photo-responsive droplet manipulation functional surface[J]. Opto-Electron Eng, 2023, 50(3): 220326. doi: 10.12086/oee.2023.220326

Citation:

Zhang C, Wen T, Liu Z Z, et al. Research and application advances of photo-responsive droplet manipulation functional surface[J]. Opto-Electron Eng, 2023, 50(3): 220326. doi: 10.12086/oee.2023.220326

Research and application advances of photo-responsive droplet manipulation functional surface

1.
Institute of Photonics & Photon Technology, Northwest University, Xi’an, Shaanxi 710127, China
2.
College of Optical Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310007, China

Fund Project: National Major Scientific Research Instrument Development Project of China (51927804), National Natural Science Foundation of China (62275216, 61378083, 61405159, 11504294), Cultivated project for Major Research of National Natural Science Foundation of China (91123030), and Science and Technology Innovation Team Project of Shaanxi Province (S2018-ZC-TD-0061)

More Information

^*Corresponding authors: nwuzchen@nwu.edu.cn; bjt@nwu.edu.cn

Received Date 02 December 2022

Revised Date 09 February 2023

Accepted Date 10 February 2023

Available Online 16 March 2023

Published Date 25 March 2023

Abstract

Abstract

Functional surface with specific wettability is one of the indispensable means for droplet manipulation. In recent years, the photo-responsive functional surface with changeable wettability has developed fast. By inducing wetting gradient force, mechanical deformation, phase transformation, dielectric electrophoresis force and electro wettability alteration on the material surface, the behavior of the droplets can be controllably manipulated by the photo-responsive functional surface. In this paper, the development of the photo-responsive functional surface for the droplet manipulation was briefly reviewed. The principles and mechanisms of the droplet manipulation with the functional surface had been expatiated. The categories, structural characteristics and corresponding preparation techniques of the functional surface were analyzed and summarized. In addition, the applications of the photo-responsive functional surface in droplet transportation, fusion, fission, liquid robot, and fluidic chips were introduced in detail. The development tendency and potential applications of the photo-responsive droplet manipulation functional surface were prospected in combination with the characteristics of the functional surface.
- photo-responsive /
- functional surface /
- droplet manipulation /
- wettability

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References

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Overview

Overview

In nature, many creatures have evolved the ability of water droplets transportation or collection. Such as, lotus leaf has the ability of "out of the silt without fouling", the butterflies can fly in the rain for their special wing structures, cactus can use its spikes to collect droplets from the air, and desert animals like beetles and lizards can collect droplets through their shells and scales, and so on. In the past few decades, human beings imitated from nature, and many functional surfaces capable of manipulating droplets have been prepared and widely used in self-cleaning, anti-fog, anti-ice, water harvest, pollution control, and so on.

With time passes by, the "passive" droplet control of bionic wettability functional surface can no longer meet the demands of people in production. So, it is of great significance to develop functional surfaces which can actively control the droplets with the external simulations. Among the various wettability responsive droplet control methods, photo-responsive droplet manipulation has attracted great attention due to its advantages such as remote, non-contact, flexible control of the droplets, and strong anti-electromagnetic interference ability.

Despite long response time and low speed in the early stage of the photo-responsive droplet manipulation, in recent years, the technology of photo-responsive droplet manipulation functional surface has been developed dramatically. The droplet-controlled surfaces with fast response have been realized by wettability variation, mechanical deformation, phase transition, and charge distribution induced by light.

Such as, by using the photothermal effect of materials, the surface tension of the lubrication layer on the surface of materials can be changed, thus creating a wetting gradient force to push the droplets to move. Further, the sliding and pinning of the droplet can be controlled by the phase change of the paraffin layer on some functional surfaces. The pyroelectric crystal can generate the dielectric force field on its surface based on the photothermal effect, which could be applied to realize the lossless moving, merging, and splitting of the droplets. In addition, the wettability of the photovoltaic crystals could be changed with the irradiation of light, therefore, can be used to control the behavior of droplets. In this paper, the development of the photo-responsive functional surface in droplet manipulation was briefly reviewed. The mechanisms of the droplet manipulation with the functional surface were expatiated. The categories of functional surfaces were summarized, the characteristics of the structure were analyzed, and the corresponding implementation method was introduced in detail. In addition, the applications of the photo-responsive functional surface in droplet transportation, fusion, and segmentation were introduced. Finally, the future development and potential applications of the photo-responsive functional surface for droplet manipulation were prospected.