Boostream: a dynamic fluid flow process to assemble nanoparticles at liquid interface

Abstract

Abstract. CEA-LITEN develops an original process called Boostream ® to manipulate, assemble and connect micro-or nanoparticles of various materials, sizes, shapes and functions to obtain monolayer colloidal crystals (MCCs). This process uses the upper surface of a liquid film flowing down a ramp to assemble particles in a manner that is close to the horizontal situation of a Langmuir-Blodgett film construction. In presence of particles at the liquid interface, the film down-flow configuration exhibits an unusual hydraulic jump which results from the fluid flow accommodation to the particle monolayer. In order to master our process, the fluid flow has been modeled and experimentally characterized by optical means, such as with the moiré technique that consists in observing the reflection of a succession of periodic black-and-red fringes on the liquid surface mirror. The fringe images are deformed when reflected by the curved liquid surface associated with the hydraulic jump, the fringe deformation being proportional to the local slope of the surface. This original experimental setup allowed us to get the surface profile in the jump region and to measure it along with the main process parameters (liquid flow rate, slope angle, temperature sensitive fluid properties such as dynamic viscosity or surface tension, particle sizes). This work presents the experimental setup and its simple model, the different experimental characterization techniques used and will focus on the way the hydraulic jump relies on the process parameters.

Piezo-Potential Generation in Capacitive Flexible Sensors Based on GaN Horizontal Wires

“…The realization of flexible capacitive piezoelectric sensor based on the assembly of horizontal MOVPE -polar GaN wires has been demonstrated with the Boostream ® technique [ 28 ]. A layer of long wires (>100 µm) that can be textured in stripes is embedded into parylene and the voltage is measured between metallic electrodes deposited on both top and bottom sides.…”

“…Wires trapped at the liquid interface are driven by hydrodynamic forces to the “transfer zone” where they accumulate gradually leading to their self-assembly as a compact monolayer film. The film obtained, thanks to the packing of wires, can be then transferred onto a substrate positioned at the end of the transfer area by applying a slow withdrawing movement (few cm/min) [ 28 ].…”

“…Simple model calculations demonstrate here that the assembly process is a key step and that wires polarities should be precisely controlled to improve the efficiency of horizontally assembled wires-based capacitive devices. This point has not been optimized up to now by using Langmuir-Blodgett [ 26 ], the Boostream ® technique [ 28 ] and other assembling techniques [ 25 ]. It should be the focus of further experimental studies.…”

“…This paper will address the basic understanding of the physical mechanisms involved in capacitive sensors based on horizontal wire-assembly taking an example of the realization of an experimental device and also studying the problem with finite element modelling (FEM). The horizontal assembly ultra-long GaN MOVPE-wires will be performed with the Boostream ® assembly technique [ 28 ] that provides a solution for mass-production on large surfaces (several square meters). Then, the GaN wire layer transferred with this method will be packed in a capacitive structure to fabricate flexible capacitive sensors.…”

Microstructured antireflective encapsulant on concentrator solar cells

“…Simulations confirm that the PDMS layer is optically incoherent and that the thickness uncertainty has negligible effects on the optical performance of the device. Subsequently, we deposit a monolayer of hexagonally close‐packed silica beads on the PDMS, using a patented method based on a dynamic fluid flow process, called Boostream, described in Delléa and Lebaigue 30 . This method involves first depositing the beads on an easy‐to‐handle substrate, 31 then transferring them onto the PDMS surface.…”