Microfluidic systems including microchannels and microvalves, fabricated by micromachining technology, are studied with approached models, either analytical or by simulation. The modelling of rectangular channel and passive valves is presented in this paper, which is divided in three parts. At first, the analytical modelling of a channel versus its shape factor and a normalisation of its fluidic comportment is presented. Then a description of the diffuser-nozzle valve is purposed by applying the general Bernoulli equation. The efficiency of this valve is found to be determined by the value of the shape factor and angle of the diffuser element. The third part is dedicated to numerical simulation of a Tesla diode and purpose an optimisation of its efficiency versus the Tesla geometry. Finally, the realisation and characterisation of prototypes are exposed. Characterisation were applied to rectangular channel and showed good agreement with the analytic modelisation. The analytic expressions, that have been found, can be used in simulations of the flow sensors through the construction of an equivalent electric circuit, and subsequently analysed using SPICE or similar tool Simulink Matlab.
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.