More and more functional inks are developed to enlarge the applications of inkjet printing. Yet, the stability of the inks is often challenging. For example, particles might agglomerate and clog the printhead, eventually compromising the whole printing process. Having a reliable filtering system is therefore key for complex inks. Here, we present a novel passive filtering system based on the inertial microfluidic concept that can potentially be used to filter inkjet inks in a continuous manner. The system has been first optimized thanks to numerical simulations and then characterized experimentally.