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

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

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

Real-time optimization-based control for dielectrophoresis

Tato práce popisuje návrh řízení pro bezkontaktní manipulaci s mikro- a mezoskopickými objekty pomocí dielektroforézy. Konkrétně je dokumentován výchozí stav systému založeného na optimalizaci v reálném čase. Řešený problém je dále rozšířen tak, aby byly umožněny současné změny amplitud a fázových posunů napěťových signálů použitých k ovládání. Pro řešení dané optimalizační úlohy je zvolena vhodná numerická metoda a systém je experimentálně ověřen. Použita jsou dvě různá elektrodová pole umožňující pohyb po přímce a v ploše. Dále jsou analyzovány a řešeny problémy spojené se škálovatelností systému, jako jsou rostoucí výpočetní nároky a vzájemné silové působení částic.This thesis describes the control design for a noncontact manipulation of micro- and mesoscale objects utilizing the dielectrophoresis. Specifically, the currently available system based on an optimization in real-time is documented. The optimization problem is further extended so that changes in both the amplitudes and the phase shifts of the voltage signals are used for actuation. A suitable numerical solver is chosen for the given optimization task and the system is experimentally verified. The two different electrode arrays allowing linear and planar motion are used. Furthermore, the issues related to the system scalability, such as the growing computational demands and mutual particle force interactions, are analyzed and appropriate solutions proposed

Distributed manipulation by controlling force fields through arrays of actuators

Tato práce se zaměřuje na řízení distribuované manipulace prostřednictvím fyzikálních polí vytvářených maticí akčních členů. Práce se zabývá především manipulací s objekty pomocí nehomogenního elektrického a magnetického pole - dielektroforézou a magnetoforézou. Pro oba principy jsou odvozeny matematické modely vhodné pro začlenění do zpětnovazební řídicí smyčky. Modely mají v obou doménách podobnou strukturu, která dovoluje vývoj jednotného řídicího systému. Nelineární model dynamiky systému je v každé vzorkovací periodě invertován pomocí numerického řešení optimalizačního problému. Výhodou navržené strategie řízení je, že dovoluje paralelní manipulaci - nezávislou manipulaci s několika objekty najednou. Práce vedle teoretických konceptů popisuje také technické detaily experimentálních platforem spolu s výsledky mnoha experimentů. Pro dielektroforézu je navrženo nové uspořádání elektrod, které umožňuje manipulaci s více objekty v rovině a zároveň vyžaduje pouze jednovrstvou výrobní technologii. Na algoritmické straně práce představuje nové použití fázové modulace napětí pro řízení dielektroforézy. Dále také popisuje součásti vyvinuté instrumentace, jako jsou vícekanálové generátory pro řízení dielektroforézy prostřednictvím amplitudové a fázové modulace a optické měření polohy v reálném čase pomocí senzoru bez objektivu. Pro magnetoforézu je detailně popsána modulární experimentální platforma sestávající se z pole cívek se železnými jádry. Díky modularitě může být platforma použita k ověření nejen centralizovaných, ale také distribuovaných řídicích systémů.This work focuses on the control of distributed manipulation through physical fields created by arrays of actuators. In particular, the thesis addresses manipulation of objects using non-uniform electric and magnetic fields---dielectrophoresis and magnetophoresis, respectively. In both domains, mathematical models suitable for incorporation into a feedback control loop are derived. The models in the two domains exhibit a similar structure, which encourages the development of a unified approach to control. The nonlinear model of the system dynamics is inverted by solving a numerical optimization problem in every sampling period. A powerful attribute of the proposed control strategy is that a parallel manipulation---the simultaneous and independent manipulation of several objects---can be demonstrated. Besides the theoretical concepts, the thesis also describes technical details of experimental platforms for both physical domains, together with outcomes from numerous experiments. For dielectrophoresis, a new layout of electrodes is documented that allows full planar manipulation while requiring only a one-layer fabrication technology. On the algorithmic side, work presents a novel use of phase modulation of the voltages to control dielectrophoresis. Dedicated instrumentation is also discussed in the thesis such as multichannel generators for control of dielectrophoresis through amplitude and phase modulation and optical real-time position measurements using common optics and a lensless sensor. For magnetophoresis, a modular test bed composed of a planar array of coils with iron cores is described in detail. Thanks to the modularity, the platform can be used for verification of not only the centralized but also distributed control strategies

OPTIMAL CONTROL OF OBJECTS ON THE MICRO- AND NANO-SCALE BY ELECTROKINETIC AND ELECTROMAGNETIC MANIPULATION: FOR BIO-SAMPLE PREPARATION, QUANTUM INFORMATION DEVICES AND MAGNETIC DRUG DELIVERY

In this thesis I show achievements for precision feedback control of objects inside micro-fluidic systems and for magnetically guided ferrofluids. Essentially, this is about doing flow control, but flow control on the microscale, and further even to nanoscale accuracy, to precisely and robustly manipulate micro and nano-objects (i.e. cells and quantum dots). Target applications include methods to miniaturize the operations of a biological laboratory (lab-on-a-chip), i.e. presenting pathogens to on-chip sensing cells or extracting cells from messy bio-samples such as saliva, urine, or blood; as well as non-biological applications such as deterministically placing quantum dots on photonic crystals to make multi-dot quantum information systems. The particles are steered by creating an electrokinetic fluid flow that carries all the particles from where they are to where they should be at each time step. The control loop comprises sensing, computation, and actuation to steer particles along trajectories. Particle locations are identified in real-time by an optical system and transferred to a control algorithm that then determines the electrode voltages necessary to create a flow field to carry all the particles to their next desired locations. The process repeats at the next time instant. I address following aspects of this technology. First I explain control and vision algorithms for steering single and multiple particles, and show extensions of these algorithms for steering in three dimensional (3D) spaces. Then I show algorithms for calculating power minimum paths for steering multiple particles in actuation constrained environments. With this microfluidic system I steer biological cells and nano particles (quantum dots) to nano meter precision. In the last part of the thesis I develop and experimentally demonstrate two dimensional (2D) manipulation of a single droplet of ferrofluid by feedback control of 4 external electromagnets, with a view towards enabling feedback control of magnetic drug delivery to reach deeper tumors in the long term. To this end, I developed and experimentally demonstrated an optimal control algorithm to effectively manipulate a single ferrofluid droplet by magnetic feedback control. This algorithm was explicitly designed to address the nonlinear and cross-coupled nature of dynamic magnetic actuation and to best exploit available electromagnetic forces for the applications of magnetic drug delivery

An overview of multiple DoF magnetic actuated micro-robots.

International audienceThis paper reviews the state of the art of untethered, wirelessly actuated and controlled micro-robots. Research for such tools is being increasingly pursued to provide solutions for medical, biological and industrial applications. Indeed, due to their small size they o er both high velocity, and accessibility to tiny and clustered environments. These systems could be used for in vitro tasks on lab-on-chips in order to push and/or sort biological cells, or for in vivo tasks like minimally invasive surgery and could also be used in the micro-assembly of microcomponents. However, there are many constraints to actuating, manufacturing and controlling micro-robots, such as the impracticability of on-board sensors and actuators, common hysteresis phenomena and nonlinear behavior in the environment, and the high susceptibility to slight variations in the atmosphere like tiny dust or humidity. In this work, the major challenges that must be addressed are reviewed and some of the best performing multiple DoF micro-robots sized from tens to hundreds m are presented. The di erent magnetic micro-robot platforms are presented and compared. The actuation method as well as the control strategies are analyzed. The reviewed magnetic micro-robots highlight the ability of wireless actuation and show that high velocities can be reached. However, major issues on actuation and control must be overcome in order to perform complex micro-manipulation tasks

Deterministic Lateral Displacement:Challenges and Perspectives

The advent of microfluidics in the 1990s promised a revolution in multiple industries from healthcare to chemical processing. Deterministic lateral displacement (DLD) is a continuous-flow microfluidic particle separation method discovered in 2004 that has been applied successfully and widely to the separation of blood cells, yeast, spores, bacteria, viruses, DNA, droplets, and more. Deterministic lateral displacement is conceptually simple and can deliver consistent performance over a wide range of flow rates and particle concentrations. Despite wide use and in-depth study, DLD has not yet been fully elucidated or optimized, with different approaches to the same problem yielding varying results. We endeavor here to provide up-to-date expert opinion on the state-of-art and current fundamental, practical, and commercial challenges with DLD as well as describe experimental and modeling opportunities. Because these challenges and opportunities arise from constraints on hydrodynamics, fabrication, and operation at the micro- and nanoscale, we expect this Perspective to serve as a guide for the broader micro- and nanofluidic community to identify and to address open questions in the field

Design and Implementation of Electromagnetic Actuation System to Actuate Micro/NanoRobots in Viscous Environment

The navigation of Micro/Nanorobots (MNRs) with the ability to track a selected trajectory accurately holds significant promise for different applications in biomedicine, providing methods for diagnoses and treatments inside the human body. The critical challenge is ensuring that the required power can be generated within the MNR. Furthermore, ensuring that it is feasible for the robot to travel inside the human body with the necessary power availability. Currently, MNRs are widely driven either by exogenous power sources (light energy, magnetic fields, electric fields, acoustics fields, etc.) or by endogenous energy sources, such as chemical interaction energy. Various driving techniques have been established, including piezoelectric as a driving source, thermal driving, electro-osmotic force driven by biological bacteria, and micro-motors powered by chemical fuel. These driving techniques have some restrictions, mainly when used in biomedicine. External magnetic fields are another potential power source of MNRs. Magnetic fields can permeate deep tissues and be safe for human organisms. As a result, magnetic fields’ magnetic forces and moments can be applied to MNRs without affecting biological fluids and tissues. Due to their features and characteristics of magnetic fields in generating high power, they are naturally suited to control the electromagnetically actuated MNRs in inaccessible locations due to their ability to go through tiny spaces. From the literature, it can be inferred from the available range of actuation technologies that magnetic actuation performs better than other technologies in terms of controllability, speed, flexibility of the working environment, and far less harm may cause to people. Also, electromagnetic actuation systems may come in various configurations that offer many degrees of freedom, different working mediums, and controllability schemes. Although this is a promising field of research, further simulation studies, and analysis, new smart materials, and the development and building of new real systems physically, and testing the concepts under development from different aspects and application requirements are required to determine whether these systems could be implemented in natural clinical settings on the human body. Also, to understand the latest development in MNRs and the actuation techniques with the associated technologies. Also, there is a need to conduct studies and comparisons to conclude the main research achievements in the field, highlight the critical challenges waiting for answers, and develop new research directions to solve and improve the performance. Therefore, this thesis aims to model and analyze, simulate, design, develop, and implement (with complete hardware and software integration) an electromagnetic actuation (EMA) system to actuate MNRs in the sixdimensional (6D) motion space inside a relatively large region of interest (ROI). The second stage is a simulation; simulation and finite element analysis were conducted. COMSOL multi-physics software is used to analyze the performance of different coils and coil pairs for Helmholtz and Maxwell coil configurations and electromagnetic actuation systems. This leads to the following.: • Finite element analysis (FEA) demonstrates that the Helmholtz coils generate a uniform and consistent magnetic field within a targeted ROI, and the Maxwell coils generate a uniform magnetic gradient. • The possibility to combine Helmholtz and Maxwell coils in different space dimensions. With the ability to actuate an MNR in a 6D space: 3D as a position and 3D as orientation. • Different electromagnetic system configurations are proposed, and their effectiveness in guiding an MNR inside a mimicked blood vessel environment was assessed. • Three pairs of Helmholtz coils and three pairs of coils of Maxwell coils are combined to actuate different size MNRs inside a mimicked blood vessel environment and in 6D. Based on the modeling results, a magnetic actuation system prototype that can control different sizes MNRs was conceived. A closed-loop control algorithm was proposed, and motion analysis of the MNR was conducted and discussed for both position and orientation. Improved EMA location tracking along a chosen trajectory was achieved using a PID-based closed-loop control approach with the best possible parameters. Through the model and analysis stage, the developed system was simulated and tested using open- and closed-loop circumstances. Finally, the closedloop controlled system was concluded and simulated to verify the ability of the proposed EMA to actuate an MN under different trajectory tracking examples with different dimensionality and for different sizes of MNRs. The last stage is developing the experimental setup by manufacturing the coils and their base in-house. Drivers and power supplies are selected according to the specifications that actuate the coils to generate the required magnetic field. Three digital microscopes were integrated with the electromagnetic actuation system to deliver visual feedback aiming to track in real-time the location of the MNR in the 6D high viscous fluidic environment, which leads to enabling closed-loop control. The closed-loop control algorithm is developed to facilitate MNR trajectory tracking and minimize the error accordingly. Accordingly, different tests were carried out to check the uniformity of the magnetic field generated from the coils. Also, a test was done for the digital microscope to check that it was calibrated and it works correctly. Experimental tests were conducted in 1D, 2D plane, and 3D trajectories with two different MNR sizes. The results show the ability of the proposed EMA system to actuate the two different sizes with a tracking error of 20-45 µm depending on the axis and the size of the MNR. The experiments show the ability of the developed EMA system to hold the MNR at any point within the 3D fluidic environment while overcoming the gravity effects. A comparison was made between the results achieved (in simulation and physical experiments) and the results deduced from the literature. The comparison shows that the thesis’s outcomes regarding the error and MNR size used are significant, with better performance relative to the MNR size and value of the error