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Crystals 2017, 7(7), 202;

External-Voltage-Free Dielectrophoresis of Liquid Crystal Droplets

Department of Photonics and Advanced Optoelectronics Technology Center, National Cheng Kung University, Tainan 701, Taiwan
Department of Electro-Optical Engineering, Kun Shan University of Technology, Tainan 710, Taiwan
Department of Optometry, Chung Shan Medical University, Taichung 402, Taiwan
Department of Ophthalmology, Chung Shan Medical University Hospital, Taichung 402, Taiwan
Graduate Institute of Electrical Engineering, National Kaohsiung First University of Science and Technology, Kaohsiung 824, Taiwan
Authors to whom correspondence should be addressed.
Academic Editor: Wei Lee
Received: 12 May 2017 / Revised: 26 June 2017 / Accepted: 30 June 2017 / Published: 3 July 2017
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This work reports, for the first time, a dielectrophoresis (DEP) effect-induced motion of liquid crystal (LC) droplets in an LC/monomer mixture sample with a poly-(N-vinyl carbazole) PVK-coated substrate without an external voltage. With the UV pre-irradiation of the PVK layer through a binary mask, a laterally non-uniform electric field can be induced between the pre-illuminated regions and the neighboring non-pre-illuminated PVK regions near the borders of the two regions. The phase separation occurs once the temperature is lower than 50 °C and the LC droplets can form in the sample. The pre-formed non-uniform field provides a DEP-like force to manipulate the small LC microdroplets in the pre-illuminated regions to effectively migrate to the adjacent non-pre-illuminated regions. The continuous supply of the LC from the pre-illuminated regions to the adjacent non-pre-illuminated regions significantly increases the diffraction efficiency of the grating sample. This study provides an insight into developing new external-voltage-free DEP-based devices that can be applied on various fields, such as photonics, displays, and biomedicines. View Full-Text
Keywords: dielectrophoresis; liquid crystal; monomer; poly-(N-vinyl carbazole) dielectrophoresis; liquid crystal; monomer; poly-(N-vinyl carbazole)

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Wu, S.-K.; Mo, T.-S.; Lin, J.-D.; Huang, S.-Y.; Yeh, H.-C.; Chen, L.-J.; Lee, C.-R. External-Voltage-Free Dielectrophoresis of Liquid Crystal Droplets. Crystals 2017, 7, 202.

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