Abstract: The present disclosure relates to a microfluidic device and a method allowing the generating and screening of combinatorial samples. A microfluidic device for producing droplets of at least one sample into an immiscible phase is provided, the device comprising a droplet maker connecting an immiscible phase channel and a sample channel having at least one sample inlet connected to at least one sample inlet channel injecting the at least one sample into the sample channel, wherein the injection of the at least one sample is controlled by at least one sample valve, so that the at least one sample flows either towards a sample waste outlet or into the at least one sample inlet channel, wherein different sample inlet channel of the at least one sample inlet channel have the same hydrodynamic resistance resulting from the length, height and width of each sample inlet channel upstream of the droplet maker.