Micro-manipulation of silicate micro-sized particles for biological applications.

International audienceThere are great challenges in biological research to study mechanical or chemical interactions between biological objects and artificial parts, to analyse the biocompatibility of artificial materials and/or to increase knowledge about biological cells. Some interaction studies between cells and artificial objects require to positioning very small objects whose typical size is comparable with cell's size (typically 5-20 micrometers). This paper presents design, building and testing of a new micro-manipulation station able to grasp, transport and release ten micrometers objects. Devoted to an existing piezoelectric microgripper, innovative end-effectors in silicon have been designed after several mechanical studies. They have been built with microfabrication processes (DRIE1) in SOI 2 wafers. For the application, the positioning of silicate crystals which contain iron close to E-Coli bacteria, new end-effectors were glued on the piezoelectric microgripper. Mounted on a three axis micropositioning stage under a videomicroscope, this innovative microgripper is able to grasp a silicate crystal of 15 micrometers in the aire and release it in the bacteria liquid medium

Feedforward and IMC-feedback control of a nonlinear 2-DOF piezoactuator dedicated to automated micropositioning tasks.

International audienceThis paper presents the characterization, modeling and precise control of a 2-dof piezoactuator dedicated to precise and automated micropositioning tasks. The piezoactuator is characterized by a strong hysteresis and a high coupling between the two axes making the synthesis of a controller very difficult. We therefore propose to compensate first the hysteresis (feedforward control) in order to obtain an approximate linear system. Afterwards, an internal model control (IMC) structure is applied (feedback control) to enhance the performances of the piezoactuator. The main advantage of the proposed approach is its simplicity both for computation and for implementation making it very convenient for realtime embedded systems. Finally, the experimental results demonstrate its efficiency and conveniency for precise positioning

Overview of microgrippers and design of a micro-manipulation station based on a MMOC microgripper

International audienceThis paper deals with an overview of recent microgrippers. As the end-effectors of micromanipulation systems, microgrippers are crucial point of such systems for their efficiency and their reliability. The performances of current microgrippers are presented and offer a stroke extending from 50 m to approximately 2mm and a maximum forces varying from 0,1mN to 600 mN. Then, micromanipulation system based on a piezoelectric microgripper and a SCARA robot is presented

Dry etching of single crystal PMN-PT piezoelectric material.

International audienceDuring the last decade, the applications of PMN-PT spread significantly. Unlike PZT, the appropriate microtechnologies for PMN-PT Piezo-MEMS aren't fully documented in the literature. This paper deals with the PMN-PT etching by inductively coupled plasma (ICP) technique, also known as DRIE. The paper quantitatively presents the etching parameters of PMN-PT by the Ar/C4F8 gas combination and reports some related useful experience

Mechanical de-tethering technique for Silicon MEMS etched with DRIE process.

International audienceGetting Micro-Electro-Mechanical Systems (MEMS) out of a wafer after fabrication processes is of great interest in testing, packaging or simply using these devices. Actual solutions require special machines like wafer dicing machines, increasing time and cost of de-tethering MEMS. This article deals with a new solution for manufacturing mechanical de-tetherable silicon MEMS. The presented solution could be done with DRIE process, already used in silicon MEMS fabrication, without additional time or cost. We are proposing a new way to create a notch on tethers linking both wafer and millimetric MEMS, especially designed to break with a specified mechanical force. A theoretical silicon fracture study, the experimental results and dimensional rules to design the tethers are presented in this article. This new technique is particularly useful for microscopic MEMS parts, and will find applications in the field of the MEMS components micro-assembly

Silicon end-effectors for microgripping tasks.

International audienceMicromanipulation is a key task to perform serial assembly of MEMS. The two-fingered microgrippers are usable but require specific studies to be able to work in the microworld. In this paper, we propose a new microgripping system where actuators and the end-effectors of the gripper are fabricated separately. End-effectors can thus be adapted to the manipulated micro-objects without new design and/or fabrication of the actuator. The assembly of the end-effectors on our piezoelectric actuators guarantee a great modularity for the system. This paper focuses on the original design, development and experimentation of new silicon end-effectors, compatible with our piezoelectric actuator. These innovative end-effectors are realized with the well known DRIE process and are able to perform micromanipulation tasks of objects whose typical size is between 5 μm and 1 mm

A micromanipulation cell including a microtools changer.

International audienceThis paper describes the structure of a flexible micromanipulation cell designed to perform precise pick and place operations of objects with typical sizes from 20 to 500 ¹m. This cell is composed of three linear stages (X-Y-Z), a four degrees of freedom microgripper and a microtools changer

Prototyping of a highly performant and integrated piezoresistive force sensor for microscale applications

International audienceIn this paper, the prototyping of a new piezoresistive microforce sensor is presented. An original design taking advantage on both mechanical and bulk piezoresistive properties of silicon is presented and enables to easily fabricate a very small, large range, high sensitivity with high integration potential sensor. The sensor is made of two silicon strain gages for which widespread and known microfabrication processes are used. The strain gages present a high gage factor which allow a good sensitivity of this force sensor. The dimensions of this sensor are 700mm in length, 100mm in width and 12mm in thickness. These dimensions make its use convenient with many microscale applications notably its integration in a microgripper. The fabricated sensor is calibrated using an industrial force sensor. The design, microfabrication process, and performances of the fabricated piezoresistive force sensor are innovative thanks to its resolution of 100nN and its measurement range of 2mN. This force sensor presents also a high signal to noise ratio, typically 50dB when a 2mN force is applied at the tip of the force sensor

Modelling, fabrication and validation of a high performance 2 DOF piezoactuator for manipulation.

International audienceA high-performance compact micromanipulation system is presented. The system, called the microgripper microrobot on chip (MMOC), was developed at Laboratoire d'Automatique de Besançon (LAB), France. Two main parts in the MMOC design of the MMOC are discussed: 1) the piezoactuator and 2) the end-effectors. The micromanipulator is partially frabricated in a clean room and the piezoactuator system has been machined using the ultrasonic technique. Tests of micromanipulation have been carried out under both standard laboratory conditions as well as inside a scanning electronic microscope (SEM) chamber. Displacements in the plane and out of the plane are 80 and 200 m, respectively, at 100 V and the MMOC seems to be particularly useful for pick-and-place tasks. Modeling has been performed using the Smits' model and the results confirm the validity of the model for static boundary conditions. The authors have also developed a combined charge and voltage control called Q/V , which results in an order of magnitude reduction in the hysteresis of the piezoactuator. Future work will include integrating force sensors in the micromanipulator in order to measure the manipulation force. This will allow the implementation of the feedback control in the MMOC

Microfabricated PMN-PT on Silicon cantilevers with improved static and dynamic piezoelectric actuation: development, characterization and control.

International audienceThe paper reports a new composite bimorph Piezo-MEMS actuator based on the mono-crystalline and high piezoelectric coefficient material PMN-PT. The technology is based on the gold bonding of two bulk materials (PMN-PT and Silicon) followed by the Deep Reactive Ion Etching (DRIE) on the silicon side, leading to an optimized displacement actuator. The process requires an external re-polarization, yet the piezoelectric properties are conserved. The device is characterized then modeled and operated in a closed-loop control. The actuation capabilities results are compared to the ones of a classical PZT-ceramic actuator of equivalent size, demonstrating a 3 to 4 times net gain in terms of displacement range. The dynamics are improved by a factor of 2.5X for the same actuating range. The newly microfabricated actuator is also lighter and compatible with the silicon batch fabrication. Future applications include microrobotics, microassembly, cells and gene manipulation etc