2D open loop trajectory control of a micro-object in a dielectrophoresis-based device.

International audienceIn the last years, industries have shown a global trend to miniaturize the size of the components to micron in order to reduce the dimension of the final product. At this scale, a micro-object behaves differently from the micro-scale and its behavior is affected by additional physical phenomenon such as the dielectrophoresis. Dielectrophoresis (DEP) is used to separate, manipulate and detect micro particles in several domains with high speed and precision, such as in biological cell or Carbon Nano-Tubes (CNTs) manipulations. This paper focuses on developing a 2D direct dynamic model of the microobject behavior on the base of a 3D dielectrophoretic simulator. This 2D dynamic model is used to establish an open loop control law by a numerical inversion. Exploiting this control law, a high speed trajectory tracking and high precision positioning can be achieved. Several simulated and experimental results are shown to evaluate this control strategy and discuss its performance

2D robotic control of a planar dielectrophoresis-based system.

International audienceNanosciences have recently proposed a lot of proofs of concept of innovative nanocomponents and especially nanosensors. Going from the current proofs of concept on this scale to reliable industrial systems requires the emergence of a new generation of manufacturing methods able to move, position and sort micro-nano-components. We propose to develop 'No Weight Robots-NWR' that use non-contact transmission of movement (e.g. dielectrophoresis, magnetophoresis) to manipulate micro-nano-objects which could enable simultaneous high throughput and high precision. This paper focuses on developing a 2D robotic control of the trajectory of a microobject manipulated by a dielectrophoresis system. A 2D dynamic model is used to establish an open loop control law by a numerical inversion. Exploiting this control law, a high speed trajectory tracking (10 Hz) and high precision positioning can be achieved. Several simulated and experimental results are shown to evaluate this control strategy and discuss its performance

High speed closed loop control of a dielectrophoresis-based system.

International audienceNanosciences have recently proposed a lot of proofs of concept of innovative nanocomponents and especially nanosensors. Going from the current proofs of concept on this scale to reliable industrial systems requires the emergence of a new generation of manufacturing methods able to move, position and sort micro-nano-components. We propose to develop 'No Weight Robots-NWR' that use non-contact transmission of movement (e.g. dielectrophoresis, magnetophoresis) to manipulate micro-nano-objects which could enable simultaneous high throughput and high precision. This article deals with a control methods which enables to follow a high speed trajectory based on visual servoing. The non-linear direct model of the NWR is introduced and the calculation of the inverted model is described. This inverted model is used in the control law to determine the control parameter in function of the reference trajectory. The method proposed has been validated on an experimental setup whose time calculation has been optimized to reach a control period of 1 ms. Future works will be done on the study of smaller components e.g. nanowires, in order to provide high speed and reliable assembly methods for nanosystems

Modeling and control of non-contact micromanipulation based on dielectrophoresis.

International audienceMicro and nano-particles can be trapped by a non uniform electric field through the effect of the dielectrophoretic force. Dielectrophoresis (DEP) is used to separate, manipulate and sense micro particles in several domains, such as in biological or Carbon Nano-Tubes (CNTs) manipulations. This paper tackles the creation of a closed loop strategy in order to control, using DEP, the trajectory of micro objects using vision feedback. A modeling of the dielectrophoresis force is presented to illustrate the non linearity of the system and the high dynamics of the object under dielectrophoresis . A control strategy based on the generalized predictive control method is proposed with the aim of controlling the trajectory, taking advantage of the high dynamics despite the non linearity. Simulated results are shown to evaluate our control strategy

Open loop control of dielectrophoresis non contact manipulation.

International audienceThe framework of this paper is the study of "No Weight Robots-NWR" that use non-contact transmission of movement (e.g. dielectrophoresis) to manipulate micro-objects enabling significant throughput (1Hz). Dielectrophoresis (DEP) is currently used to separate, manipulate and detect micro particles in several domains with high speed and precision, such as in biological cell or Carbon Nano-Tubes (CNTs) manipulations. A dielectrophoresis system can also be considered as a robotic system whose inputs are the voltages of the electrodes and output is the object trajectory. This "No Weight Robots" enables the positionning of the manipulted object in a 3D space. This paper is summarized the modeling principle of this new type of robots and some first results on trajectory control in 2D space

Modeling the trajectory of a microparticle in a dielectrophoresis device.

International audienceMicro- and nanoparticles can be trapped by a nonuniform electric field through the effect of the dielectrophoretic principle. Dielectrophoresis DEP is used to separate, manipulate, and detect microparticles in several domains, such as in biological or carbon nanotube manipulations. Current methods to simulate the trajectory of microparticles under a DEP force field are based on finite element model FEM, which requires new simulations when electrode potential is changed, or on analytic equations limited to very simple geometries. In this paper, we propose a hybrid method, between analytic and numeric calculations and able to simulate complex geometries and to easily change the electrode potential along the trajectory. A small number of FEM simulations are used to create a database, which enables online calculation of the object trajectory as a function of electrode potentials

Direct Current Electrokinetic Particle Transport in Micro/Nano-Fluidics

Electrokinetics has been widely used to propel and manipulate particles in micro/nano-fluidics. The first part of this dissertation focuses on numerical and experimental studies of direct current (DC) electrokinetic particle transport in microfluidics, with emphasis on dielectrophoretic (DEP) effect. Especially, the electrokinetic transports of spherical particles in a converging-diverging microchannel and an L-shaped microchannel, and cylindrical algal cells in a straight microchannel have been numerically and experimentally studied. The numerical predictions are in quantitative agreement with our own and other researchers\u27 experimental results. It has been demonstrated that the DC DEP effect, neglected in existing numerical models, plays an important role in the electrokinetic particle transport and must be taken into account in the numerical modeling. The induced DEP effect could be utilized in microfluidic devices to separate, focus and trap particles in a continuous flow, and align non-spherical particles with their longest axis parallel to the applied electric field. The DEP particle-particle interaction always tends to chain and align particles parallel to the applied electric field, independent of the initial particle orientation except an unstable orientation perpendicular to the electric field imposed. The second part of this dissertation for the first time develops a continuum-based numerical model, which is capable of dynamically tracking the particle translocation through a nanopore with a full consideration of the electrical double layers (EDLs) formed adjacent to the charged particles and nanopores. The predictions on the ionic current change due to the presence of particles inside the nanopore are in qualitative agreement with molecular dynamics simulations and existing experimental results. It has been found that the initial orientation of the particle plays an important role in the particle translocation and also the ionic current through the nanopore. Furthermore, field effect control of DNA translocation through a nanopore using a gate electrode coated on the outer surface of the nanopore has been numerically demonstrated. This technique offers a more flexible and electrically compatible approach to regulate the DNA translocation through a nanopore for DNA sequencing

Electrokinetic Manipulation of Particles and Cells in Microfluidic Devices

With the recent advancement in micro-fabrication technology, lab-on-a-chip devices have been developed in order to perform biological analysis through cell manipulation. Microchannels used in these lab-on-a-chip devices have been demonstrated to accurately perform many different cell manipulation techniques such as focusing, separation, trapping, and lysis. Although there are many methods available for these techniques, electrokinetics has been rapidly gaining popularity due to the simplicity of application and removal of the need for in channel micro-structures. This thesis studies the use of electrokinetic flow and accompanying phenomena in various structured microchannels to perform focusing, separation, trapping, and lysis of cells. Three related projects were conducted in series. First, a parametric study of the focusing of yeast cells using negative dielectrophoresis in a serpentine microchannel was studied. Focusing cells into a single stream is usually a necessary step prior to counting and separating them in microfluidic devices such as flow cytometers and cell sorters. This work demonstrated a sheathless electrokinetic focusing of yeast cells in a planar serpentine microchannel using DC-biased AC electric fields. The concurrent pumping and focusing of yeast cells arose from the DC electrokinetic transport and the turn-induced AC/DC dielectrophoretic motion, respectively. The effects of electric field (including AC to DC field ratio, and AC field frequency) and concentration (including buffer concentration and cell concentration) on the cell focusing performance were studied experimentally and numerically. A continuous electrokinetic filtration of E. coli cells from yeast cells was also demonstrated via their differential electrokinetic focusing in the serpentine microchannel. Next, negative and positive dielectrophoretic focusing were also studied in their application to particle separation in a serpentine microchannel. This work first demonstrated negative and positive dielectrophoretic focusing of by changing only the electric conductivity of the suspending fluid. Due to the channel turn-induced dielectrophoretic force, particles were focused to either the centerline or the sidewalls of the channel when their electric conductivity was lower (i.e., negative DEP) or higher (i.e., positive DEP) than that of the fluid. These distinctive dielectrophoretic focusing phenomena in the serpentine microchannel were then combined to implement a continuous separation between particles of different sizes and electric conductivities. Such separation eliminates the fabrication of in-channel microelectrodes or micro-insulators that are typically required in DEP-based separation techniques. Lastly, red blood cells were used to study cell lysis and trapping in a microchannel constriction. Cell Lysis is an important step in the analysis of intracellular contents. Electrical lysis of red blood cells was demonstrated in a hurdle microchannel using a low continuous DC-biased AC electric field amplified by channel geometry. Trapping of cells was also demonstrated using this DC-biased AC electric field, and the transition between trapping and lysis of red blood cells in this microchannel was demonstrated by simply adjusting the applied DC voltage. Further, these phenomena were used in conjunction to demonstrate the separation of Leukemia cells from red blood cells

Separation of solid-liquid and liquid-liquid phases using dielectrophoresis

Over 3 decades after dielectrophoresis (DEP) was explored and defined, it has already been successfully applied in separating and handling bioparticles in micro and sub-micro scale biotechnology. However, nearly all of DEP applications are concentrated on the analysis and manipulation of particles in sub-micron and micron scaled systems with flow rates below mL/min. So far, none is known in process engineering for DEP in a scaled up application at flow rates of liters or even cubic meters per minute. The research described in this Ph D thesis is the first that attempts to scale up DEP application. With the research results described in this thesis, the feasibility of the DEP application in separation is verified. The proved high selectivity and controllability of DEP technique grand DEP a very promising prospect in separating and manipulating particles. The whole thesis work was implemented with three main steps, basic research of DEP mechanism and its side-effects and constrains, as a proof of principle gold particle fractionation using DEP, and a lab-scaled technical application of DEP in intensifying cross-flow membrane filtration, based on four paper