Modelling of a planar magnetic micropusher for biological cell manipulations.

International audienceThe improving of the efficiency and the automation of biological cell technologies is currently of great importance. One way is to build biological micro-factories which are able to perform complete biotechnological processes automatically. This technology requires the development of new automatic cell transport system to feed work stations in microfactories. An original magnetic cell micropusher is described in this paper. The ferromagnetic pusher which is submerged in the biological medium follows the movement of a permanent magnet located in the air. This paper focuses on the modelling of the dynamic behaviour of the micropusher according to the magnet trajectory. The generic model proposed is able to determine pusher trajectory according to the micropusher magnetic properties and the permanent magnet shape and properties. This simulation tool will permit to optimize and to study cell trajectory control in further works

Trajectory modelling of a planar magnetic cell micropusher.

International audienceThe improving of the efficiency and the automation of biological cell technologies is a current high stake. One way is to build biological micro-factories which are able to perform a complete biotechnological processes automatically. This technology requires the development of new automatic cell transport system to feed work stations in microfactories. An original magnetic cell micropusher is described in this paper. The ferromagnetic pusher which is submerged in the biological medium follows the movement of a permanent magnet located in the air. This paper focuses on the modelling of the dynamic behaviour of the micropusher in function of the magnet trajectory. The generic model proposed is able to determine pusher trajectory according to the micropusher magnetic properties and the permanent magnet shape and properties. This simulation tool will allow to optimize and to study cell trajectory control in further works

Capillary force disturbances on a partially submerged cylindrical micromanipulator.

International audienceThe objective of this article is to analyse the impact of liquid surface tension on force measurement in submerged micromanipulation. Firstly, at the present, mechanical characterization of biological objects in biological liquid has significant interest. Secondly, the reduction of the surface force and adhesion forces in a submerged medium could be a relevant approach to perform reliable artificial objects micromanipulation. In both cases, the mico-nano force measurement in a liquid is a great challenge. In case of a force sensor placed out of the liquid, the measurement is disturbed by the liquid surface tension. This article proposes an analysis of these disturbances on force measurements. Some design rules are proposed to reduce disturbances. We show that the major disturbances are induced by the contact angle hysteresis and a complete method is proposed to calculate these disturbances in a micromanipulation task

Robotic Micro-assembly of microparts using a piezogripper.

International audienceThis paper deals with robotic micro-assembly of silicon micro-objects whose sizes are tens of micrometers. This production means is one of a more promising approach to realize 3D and/or hybrid microsystems. Current works in robotic micro-assembly are focused on the assembly of microobjects on a large substrate. We are focusing in the study of micro-parts assembly to build microscopic subsystems usable in larger products. This approach requires specific functionalities like a ‘micro-vise' required to block the first object during assembly. Original strategies are proposed and applied on an experimental robotic structure composed of micropositionning stages, videomicroscopes, piezogripper, and silicon endeffectors. Some experimental teleoperated micro-assemblies has validated the proposed methods and the reliability of the principles. Future works will be focused on micro-assembly automation

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

Manipulation aux échelles microscopiques.

National audienceLa manipulation robotique aux échelles microscopiques représente un enjeu majeur pour le développement des techniques biologiques et pour l'avènement de produits hautement miniaturisés réalisés par micro-assemblage. La miniaturisation d'un système de manipulation est confrontée à plusieurs ruptures de type physique ou technique, comme par exemple la prédominance des forces d'adhésion sur le comportement des micro-objets ou le changement des techniques de fabrication influençant fortement les méthodes de conception des microrobots. L'objet de l'étude de la manipulation aux échelles microscopiques porte sur la recherche de méthodes robotiques adaptées à ce nouveau paradigme : le micromonde. La compréhension et la modélisation de ce micromonde sont un corollaire essentiel à l'étude de stratégies robotiques adaptées. Basées sur cette modélisation, de nouvelles stratégies de manipulation sont étudiées en prenant en compte les comportements particuliers des micro-objets tel que les collages sur les organes terminaux. La mise en oeuvre de ces stratégies de manipulation nécessite une structure robotique complète incluant des systèmes de perception et de contrôle de l'environnement. La commande de l'ensemble soit par téléopération avec retour haptique soit en cycle automatique est enfin également un enjeu scientifique

Workshop on "Robotic assembly of 3D MEMS".

Proceedings of a workshop proposed in IEEE IROS'2007.The increase of MEMS' functionalities often requires the integration of various technologies used for mechanical, optical and electronic subsystems in order to achieve a unique system. These different technologies have usually process incompatibilities and the whole microsystem can not be obtained monolithically and then requires microassembly steps. Microassembly of MEMS based on micrometric components is one of the most promising approaches to achieve high-performance MEMS. Moreover, microassembly also permits to develop suitable MEMS packaging as well as 3D components although microfabrication technologies are usually able to create 2D and "2.5D" components. The study of microassembly methods is consequently a high stake for MEMS technologies growth. Two approaches are currently developped for microassembly: self-assembly and robotic microassembly. In the first one, the assembly is highly parallel but the efficiency and the flexibility still stay low. The robotic approach has the potential to reach precise and reliable assembly with high flexibility. The proposed workshop focuses on this second approach and will take a bearing of the corresponding microrobotic issues. Beyond the microfabrication technologies, performing MEMS microassembly requires, micromanipulation strategies, microworld dynamics and attachment technologies. The design and the fabrication of the microrobot end-effectors as well as the assembled micro-parts require the use of microfabrication technologies. Moreover new micromanipulation strategies are necessary to handle and position micro-parts with sufficiently high accuracy during assembly. The dynamic behaviour of micrometric objects has also to be studied and controlled. Finally, after positioning the micro-part, attachment technologies are necessary

Effect to the capillary force on force measurements in submerged micromanipulations.

International audienceThe subject of this article is to analyse the impact of liquid surface tension on force measurement in submerged micromanipulations. On the one hand, at the present, mechanical characterization of biological objects in biological liquid has significant interest. On the other hand, the reduction of the surface force, and adhesion forces in a submerged medium could be a good approach to perform reliable artificial objects micromanipulations. In both cases, the micro-nano force measurement in a liquid is a great challenge. In case of a force sensor placed out of the liquid, the measurement is disturbed by the liquid surface tension. This article proposes an analysis of the disturbance of the surface tension on the force measurement. Some design rules are proposed to reduce disturbances. We shows that the major disturbances are induced by the contact angle hysteresis and a complete method is proposed to calculate these disturbances in a micromanipulation task

Control of a particular Micro-Macro positioning system applied to cell Micromanipulation.

International audienceBiological research requires new tools for cell micromanipulations. Currently, biological cell sizes range from a few to hundreds of micrometers, their manipulation therefore belonging to the field of microrobotics. This paper presents a new wireless micromanipulation system which allows cells placed in a droplet of liquid to be pushed on a glass slide. The cell micropusher is a ferromagnetic object which follows the movement of a permanent magnet located under the glass slide. It has been proved in previous works that two kinds of micropusher movements can induce a movement of the pushed object: turning the micropusher around the contact point (rotation), or moving the micropusher in translation. Rotation allows an object to be placed with a precision below 1 μm ,but acts within a narrow range. Translation allows placement of an object with lower accuracy, but within a wide range. We propose a specific coarse-fine control strategy to push an object, with good precision, within a wide range. Furthermore, experimentation on polystyrene balls of 50 μm in diameter, and immature human oocytes of 150 μm in diameter are presented

Smart microrobots for mechanical cell characterization and cell convoying.

International audienceThis paper deals with the effective of smart microrobots for both mechanical cell characterization and cell convoying for in vitro fertilization. The first microrobotic device was developed to evaluate oocyte mechanical behavior in order to sort oocytes. A multi-axial micro-force sensor based on a frictionless magnetic bearing was developed. The second microrobotic device presented is a cell convoying device consisting of a wireless micropusher based on magnetic actuation. As wireless capabilities are supported by this microrobotic system, no power supply connections to the micropusher are needed. Preliminary experiments have been performed regarding both cell transporting and biomechanical characterization capabilities under in vitro conditions on human oocytes so as to demonstrate the viability and effectiveness of the proposed setups