We demonstrate a sandwich configuration for microfluidic manipulation in LiNbO3 platform based on photovoltaic effect, and the behaviours of dielectric microdroplet under this sandwich configuration are investigated. It is found that the microdroplet can generate in the form of liquid bridge inside the LiNbO3-based sandwich structure under the governing dielectrophoretic force, and the dynamic process of microdroplet generation highly depends on the substrate combinations. Dynamic features found for different combinations are explained by the different electrostatic field distribution basing on the finite-element simulation results. Moreover, the electrostatic field required by the microdroplet generation is estimated through meniscus evolution and it is found in good agreement with the simulated electrostatic field inside the sandwich gap. Several kinds of microdroplet manipulations are attempted in this work. We suggest that the local dielectrophoretic force acting on the microdroplet depends on the distribution of the accumulated irradiation dosage. Without using any additional pumping or jetting actuator, the microdroplet can be step-moved, deformed or patterned by the inconsecutive dot-irradiation scheme, as well as elastically stretched out and back or smoothly guided in a designed pass by the consecutive line-irradiation scheme.
We demonstrate an active and controllable photo-assisted splitting of dielectric microdroplets inside a LiNbO3-based sandwich structure by utilizing the pyroelectric and photovoltaic effects of LiNbO3 crystals. Basing on electrostatic simulation results, the mechanism of the photo-assisted splitting is explained; meanwhile, the microdoplet pre-polarizing and the inclined electrostatic force induced by the photovoltaic charges inside the sandwich structure are emphasized. We also study the dependence of the splitting part size on the substrate temperature variation, the irradiation intensity, and the duration. Featured dependence is found to follow the theoretical curve predicted by the compensation between the photo-excited and bound surface charges.
We report the photo-assisted proton exchange and chemical etching on Fe-doped LiNbO(3) crystals. Selective proton exchange and chemical etching are realized through the 455nm-laser irradiation on the crystal surface in pyrophosphoric acid. Optical microscopy and Micro-IR spectroscopy analysis show that the hydrogen incorporation is confined spatially by the laser irradiation. Moreover, under the laser irradiation, + z surface is found to be more easily etched than -z surface. This unexpected etching anisotropy is attributed to the photogalvanic effect of the crystal.
Patterned LiNbO 3 thin films basing aqueous precursor are fabricated in photolithography and laser-induced crystallization ways. The effects of LN gel solubility, laser scanning parameters and substrate temperature on the pattern quality of LN film are demonstrated. We emphasize the importance of the temperature gradient at the crystallization front to the pattern quality for laser-induced crystallization. Moreover, the distinct morphology features (porous and compact) of patterned LN films fabricated in the two ways are shown and explained by their difference of crystallization modes. These two fabrication ways are suggested for the integrated-optical and biomedical applications, respectively.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.