Electro-switchable polydimethylsiloxane-based optofluidics

Abstract

We report on the fabrication and characterization of a new generation of electro-switchable optofluidic devices based on flexible substrates, combined with the extraordinary properties of reconfigurable soft-materials. A conductive polydimethylsiloxane microstructure has been first sputtered with an Indium Tin Oxide (ITO) layer and then functionalized with an amorphous film of SiO(x). Then, the "layer" by "layer" microstructure has been infiltrated with an anisotropic and reconfigurable fluid (Nematic Liquid Crystal, NLC). The sample has been characterized in terms of morphological, optical and electro-optical properties: the soft-conductive microstructure exhibits a uniform and regular morphology, even after testing with mechanical stretching and deformations. Combination of the conductive ITO with the functionalization film (which has been employed for inducing in-plane alignment of NLC molecules) enables us to carry out a series of optical and electro-optical experiments; these confirm excellent properties in terms of a reconfigurable device and a diffractive element as well.

Polarization-Independent Nematic Liquid Crystal Waveguides for Optofluidic Applications

“…Optofluidic channels have been successfully proposed by infiltrating LC in PDMS to demonstrate the variation in the diffraction pattern of an array of microfluidic channels acting as an electro-optic grating [13]. An interesting advantage of PDMS with respect to other materials, such as silicon or glass, is the easy and cheap technological processing to make patterned geometries.…”

Stimuli responsive diffraction gratings in soft-composite materials

“…Unfortunately, where display oriented applications are concerned, the insulating properties of materials like PDMS, represent strong limitations for realizing electrically switchable devices. In this framework, De Sio et al [50] had overcome the intrinsic insulating properties of PDMS by sputtering a thin layer of indium tin oxide (ITO). Figure 9(a) shows the SEM view of the PDMS DG after the ITO deposition.…”

Variations in the charge-transport, nonlinear optical, and electro-optical properties of RM734 due to halogenation: a quantum mechanical study

“…Due to large values of nonlinear properties in RM734 LC, its nematic phase has been investigated for use in the fabrication of optical controlled cores for switchable and reconfigurable waveguides, 23 in photonic LC fibers, 24 and for optofluidic applications. 25 In the present study, the polarizabilities and first-order hyperpolarizability were studied to ensure the nonlinear behavior of the RM734 nematic LC and its halogen substituents. Later, an electric field was applied to these liquid crystal molecules and the different electro-optical properties were evaluated.…”