Combinatorial nanoparticle patterns assembled by photovoltaic optoelectronic tweezers

Abstract

Photovoltaic optoelectronic tweezers (PVOTs) have been proven to be an efficient tool for the manipulation and massive assembly of micro/nano-objects. The technique relies on strong electric fields produced by certain ferroelectric materials upon illumination due to the bulk photovoltaic effect (customarily LiNbO3:Fe). Despite the rapid development of PVOTs and the achievement of high-quality 1D and 2D particle patterning, research efforts aimed at the fabrication of combinatorial structures made up of multiple types of particles have been scarce. Here, we have established the working principles of three different methods to tackle this pending challenge. To that end, dielectrophoresis and/or electrophoresis acting on neutral and charged particles, respectively, have been suitably exploited. Simple mixed structures combining metallic and dielectric nanoparticles of different sizes have been obtained. The results lay the groundwork for future fabrication of more complex combinatorial structures by PVOT, where micro/nanoparticles are the basic building blocks of miniaturized functional devices.

Trifurcated Splitting of Water Droplets on Engineered Lithium Niobate Surfaces

“…More commonly, they are illuminated with visible light that induces electric charges on their surface due to the photovoltaic effect, generating an internal electric field that can easily reach strengths of hundreds of kV/cm . The evanescent field, that is, the photoinduced electric field acting outside the illuminated Fe:LiNbO 3 , interacts with neutrally charged micro-objects through dielectrophoretic forces that can be used to actively manipulate them. − It should be noted that the term “evanescent” is used in the specialist literature to indicate electric fields that extend outside a globally neutral slab. ,− , More recently, the photovoltaic effect has also been exploited to actuate water droplets on open surfaces. , In particular, we have succeeded in the realization of a flexible optofluidic platform based on z -cut iron-doped lithium niobate crystals coated with a slippery liquid-infused surface (LIS) , that guarantees robust and reliable manipulation of droplets . These biomimetic surfaces are textured materials infused with a suitable oil.…”

Photovoltaic Rotation and Transportation of a Fragile Fluorescent Microrod Toward Assembling a Tunable Light-Source System

“…Recently, LiNbO 3 (LN) crystals started to become a promising platform for biophotonics due to their biocompatibility and optical integrability. − LN-based photovoltaic strategy for manipulating micro/nano-objects attracted broad interests due to its flexible feature. ,− In spite of the progress of photovoltaic manipulation, the continuous rotation of an individual microrod has never been reported because of the complexity of the electrostatic interaction between the microrod and the photovoltaic field. In fact, the photovoltaic process directly converts a visible light profile to a spatial modulation of charge density, and the surface charges can be confined extremely by the light profile to create a strong local electrostatic field. − , This field can extend over a large area next to the light spot, and thus, it can be utilized for manipulating an individual microrod while minimizing the coverage of the light spot on the microrod.…”

Laser-induced crystallization of fluoranthene in both vapor and solution media

“…A method is therefore needed to achieve in-situ capture of the organic molecules at the beginning of the growth, which involves the manipulation of the tiny particles to adjust the growth position. Manipulation of micro-scale objects by laser is a popular technique in biochemical research, which includes photo-induced dielectrophoresis (DEP) [8][9][10][11][12][13][14] and electrophoresis (EP), [15][16][17] as well as optical tweezers [18][19][20] and photophoresis (PP). [21][22][23][24][25][26][27] The manipulation of the DEP force is achieved through the polarization of the dielectric material by the non-uniform electric field.…”