Numerical and Experimental Study of Optoelectronic Trapping on Iron-Doped Lithium Niobate Substrate

Abstract

Optoelectronic tweezers (OET) are a promising technique for the realization of reconfigurable systems suitable to trap and manipulate microparticles. In particular, dielectrophoretic (DEP) forces produced by OET represent a valid alternative to micro-fabricated metal electrodes, as strong and spatially reconfigurable electrical fields can be induced in a photoconductive layer by means of light-driven phenomena. In this paper we report, and compare with the experimental data, the results obtained by analyzing the spatial configurations of the DEP-forces produced by a 532 nm laser beam, with Gaussian intensity distribution, impinging on a Fe-doped Lithium Niobate substrate. Furthermore, we also present a promising preliminary result for water-droplets trapping, which could open the way to the application of this technique to biological samples manipulation.

Electrophoretic Versus Dielectrophoretic Nanoparticle Patterning Using Optoelectronic Tweezers

“…These characteristics together with its efficiency and low cost are making PVT a competitive tool for organic and inorganic particle manipulation. This technique has been successfully applied in different fields including (i) microfluidics for microdroplet dynamic deformation, patterning, and splitting [12][13][14] and particle desorption mass spectrometry microchannel fabrication [15], (ii) plasmonics, as a tool for obtaining plasmonic platforms for fluorescence enhancement of organic and biomolecules [16], (iii) biophotonics and biomedicine as a method of killing cancer cells [17] and for bacteria, pollen, and spore arranging [18,19], and (iv) photonics, for the fabrication of flexible diffractive optical elements [20].…”

Recent Achievements on Photovoltaic Optoelectronic Tweezers Based on Lithium Niobate

“…In that work, the crystal substrate had the polar axis parallel to the surface, x-or y-cut, (see Figure 2a,b). A recent work [27] includes a theoretical study for the same x-/y-cut geometry and using a very similar model than that of reference [26] but applied to a cylindrical light beam. Additionally, since 2013 another configuration with the polar axis normal to the surface, i.e., z-cut, (see Figure 2c) has been often employed in relation to 2D patterning (see Section 3) and a simple model to describe it has been already reported [28,29].…”

“…Gazzeto et al [27] reported in 2016 that they were not able to observe DEP force on dielectric particles dispersed in water or any aqueous solution. No trapping or repulsive DEP force was observed on micro-particles in aqueous medium.…”

Optofluidic platform using liquid crystals in lithium niobate microchannel

“…The continuing popularity of LiNbO 3 in this area originates from its highly desirable properties, such as large electro-optic, acousto-optic, piezoelectric and nonlinear optical coefficients, and its quite easy production in a single-domain state 2,3 . Moreover, this material has recently been proposed as optically active substrate for the realization of microfluidic devices 4,5 , thus paving the way for its use in the optofluidic field. On the other hand, liquid crystals (LC) are known for their sensitiveness to external stimuli, among which optical and electric fields are widely used in photonics and display applications 6,7 .…”