Electrical analogies applied on a volumetric micropump “highlighting of its fluidic resonant frequency” Olivier Français and Samir Bendib Group ESIEE, Cité Descartes, BP 99 93162 Noisy le Grand Cedex France Tel: 01 45 92 65 86, Fax: 01 45 92 66 99 bendibs@esiee.fr, o.francais@esiee.fr ABSTRACT This paper deals with a simple way for optimising the design of a valve-less micropump. The method is based on electric analogies. The micropump is compared to an electrical circuit similar to a RLC circuit. By this way, the fluidic resonant frequency of the micropump can be evaluated despite a non-linear working due to the used of micro-valve. The results are applied on the design of an electrostatic micropump with a specific electrode shape in order to control the micropump resonant frequency. In order to validate the modelling, a prototype of electrostatic micropump is realised. The micropump is composed of three different wafers associated by bonding techniques. KEYWORD list : Electrostatic Micropump, Electric Analogy, Modelling, Resonant frequency 1. INTRODUCTION With MEMS, a lot of innovative applications had emerged in the field of microfluidic (Inkjet printer head, micromixer, microanalysis device) [1]. Micropump is one of the key success for controlling microfluidic transmission. But the apparent complexity of such a system induces heavy simulator based on FEM methods or a specific simulator [2]. A more simple method is the use of electrical analogies. Representing a micropump with electric networks enables the use of classic electric simulator such as Pspice. Simulations are obtained very quickly and enable parameter variations. This method has been used in order to evaluate the fluidic resonant frequency of an electrostatic micropump. The electrostatic excitation was supposed to be in a linear mode (similar to a pneumatic actuator). 2. DESCRIPTION OF AN ELECTROSTATIC VALVE-LESS MICROPUMP In order to obtain a fluidic displacement, a volume chamber is associated to an actuator in order to modify its geometry. Usually, a diaphragm is used. Two symmetrical valves are designed to control the flow direction. The shape of the valve enables to obtain a greater flow in direct direction than reverse. The valves are connected to a tank or external tubes (Fig. 1). Glass Wafer Si Wafer SOI Wafer Connection Electrostatic excitation Membrane Valve Figure 1 : Representation of the electrostatic micropump