Manipulation of Micro-objects using Adhesion Forces and Dynamical Effects in Unconstrained Environment
This paper describes a dynamical strategy for releasing objects picked-up by means of adhesion forces. Indeed, if sticking effects are used in order to capture an object by adequately choosing a high surface energy constitutive material for the end-effect
- PDF / 1,668,211 Bytes
- 11 Pages / 481.89 x 691.654 pts Page_size
- 14 Downloads / 173 Views
1 Introduction In last years, micro-manipulation has become a rising research field due to the recent developments in biology, micro-electronics and tele-surgery. New industrial and biological applications in need of accurate manipulation methods are more and more frequent [Arai and Fukuda (1997)],[Yang et al. (2001)]. Different studies approached the problem adopting the miniaturization method, reproducing macro-scale manipulation systems at micro-scale. Some examples are the chop-sticks gripper of MEL [Tanikawa et al. (1996)] and the 3-finger manipulator of LAB Besanon [Calin et al. (1997)]. The second approach is to use nano-manipulation methods for micro-manipulation [Curran et al. (1997)]. Finally, the last method consists of using microscale specificities to develop dedicated manipulation systems, such as the vacuum tool at EPFL [Danuser et al. (1997)] which takes into account adhesion and then uses suction forces higher in magnitude in order to neglect the sticking effects. Since 1996, Sato has opened the way of using surface forces by means of capture of microobjects [Miyazaki and Sato (1997)], but in a constrained environment. Our goal is to achieve capture and release of micro-objects using only adhesion forces in a non-constrained environment, i.e in normal laboratory conditions. The capture phase of the manipulation is at present well mastered. A manipulator has been designed in this aim. The gripper is a gold coated piezoresistive silicon micro-beam exhibiting a high surface energy, in order to facilitate the capture. The problem is to overbalance this adhesion for the release, in case the object has to be placed on a substrate with a lower surface energy. A solution is the use of dynamic effects such as inertia. In the first part of this paper the theoretical approach will be described to show the constraints of the adhesion based on capture and release of micro-objects. In the second part the design of the experimental set-up and finiteelements studies aiming to define the dynamic behavior of the sub-parts of the system will be discussed. Simulations of the dynamic model will show the pertinence of obtained results. Then, first experiments will prove the dynamic capabilities of the micro-gripper. Finally, a complete experimentation consisting of the manipulation of glass micro-spheres will be presented as the G. Bianchi et al. (eds.), Romansy 14 © Springer-Verlag Wien 2002
D. Haliyo, S. Regnier and J.C. Guinot
152
conclusion proving the efficiency of the proposed solution based on adhesion forces and dynamic compensation. 2
Theoretical Approach
The manipulation task on which the modeling is based consists in picking up a sphere ("object") initially laying on a planar surface ("substrate") using a simple tool ("end-effector"), here a rectangular silicon cantilever; then placing it on a selected location on the same substrate. The end-effector is supposed to have a higher surface energy than the substrate, exhibiting a stronger Van der Waals potential. Considering this simple task used to illustr
Data Loading...
