A new design of fluidic microdiode is proposed. An initial numericalsimulation of this so-called vortex microdiode allows us to understand theworking principle of the diode. It is shown that the complex relationshipbetween the inertial and viscous effects may lead to paradoxical results: asan example, an increase in the viscosity can involve an increase in the flowrate. The simulated performances, confirmed by experimentalmeasurements with a microdiode etched by deep reactive ion etching on asilicon wafer, are compared to the performances of other microdiodesdescribed in the literature. The efficiency of the vortex microdiode is foundto be comparable to that of the Tesla microdiode, which was the mostefficient microdiode. This is very encouraging, all the more so since theoptimization perspectives are varied, due to a sophisticated design.