David Hériban

Robotic micro-assembly of microparts using a piezogripper

This 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 micro-objects 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 dasiamicro-visepsila required to block the first object during assembly. Original strategies are proposed and applied on an experimental robotic structure composed of micropositioning stages, videomicroscopes, piezogripper, and silicon end-effectors. 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.

Submerged Robotic Micromanipulation and Dielectrophoretic Micro-object Release

The development of new hybrid microsystems needs new technologies which are able to perform assembly of small micro-objects. Now, the current micromanipulation technologies are still unreliable for micro-objects which typical size is down to hundred micrometers. Consequently, the study and the development of innovative artificial micro-object manipulation strategies in these dimensions is particularly relevant. As presented in the literature, micromanipulations are perturbed by the adhesion and surface forces which depend on surrounding mediums. We propose to perform micro-assembly tasks in liquid medium, because adhesion and surface forces applied on submerged micro-objects are less important than in air. The comparative analysis of micro-forces in air and in liquid is presented in this paper. Although the micro-forces reduce in liquid, they stay disturbed the micro-objects release. Thus, we propose to extend the dielectrophoresis micromanipulation principles which are currently done in the biological micromanipulation to submerged artificial objects micro-assembly. The negative dielectrophoresis principle is used to release a micro-object grasped with a micro-gripper. Physical principle and first experimentations is presented in this article. Further works will focus on the optimization of the principle, and on the micro-object release modelling and control

A mechanical de-tethering technique for silicon MEMS etched with a DRIE process

Getting 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 paper deals with a new solution for manufacturing mechanical de-tetherable silicon MEMS. The presented solution could be done with a 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 paper. This new technique is particularly useful for microscopic MEMS parts, and will find applications in the field of the MEMS components microassembly.

Nonlinear modeling for a class of nano-robotic systems using piezoelectric stick-slip actuators

This paper addresses modeling issues for a class of nano-robotic systems using piezoelectric stick-slip actuators. The work focuses on the friction force modeling to describe the dynamics of a stick-slip actuator in a wide operating range needed in nano-robotics. Based on the theory of the single state elasto-plastic model and on an experimental analysis, necessary conditions on presiding modeling are highlighted. The conditions allow describing the dynamics of stick-slip type actuators for both scanning mode and stepping mode in the time and the frequency domains and for backward and forward directions of the motion. The proposed dynamic model opens new perspective for closed loop control of nano-robotic system.

Improving rotation behaviour of robotic structures for micro-assembly

Serial micro-assembly requires high precision robots able to produce translations and rotations to position and orient objects during assembly. In micro-scale, the translation ranges required are typically up to the millimeter and can be obtained with smart devices (piezomotor, etc.). In the other hand, the rotation ranges stay identical to the macroscale (eg. 90deg) and require standard guidings like ball bearings which induce disturbances on the linear position. Thus the ability to produce high precision robots where translations and rotations are decoupled is currently one of the major stake in micro-assembly. This paper deals with an original modeling of the coupling between rotation and linear position. The geometrical model is presented and two calibration methods are discussed. Our method were tested on a 3 DOF planar robotic systems and the coupling was reduced by 93%.