A modular microfluidic sample preparation system, wherein the system comprises: - a first preparation module arranged in a first plane, - the first preparation module comprising a first surface and an opposing second surface and being delimited by first lateral faces, - the first preparation module further comprising an outlet arranged at the second surface of the first preparation module and an inlet, the inlet and the outlet being connected via a first microfluidic channel system, - a second preparation module arranged in a second plane substantially parallel to the first plane, - the second preparation module comprising a first surface and an opposing second surface and being delimited by second lateral faces, - the second preparation module further comprising an intake arranged at the first surface of the second preparation module, wherein the intake comprises a blood separation filter, the intake being connected to a second microfluidic channel system, and wherein, - the first preparation module is connected to the second preparation module so that the second surface of the first preparation module is facing towards the first surface of the second preparation module and so that the outlet of the first preparation module faces the intake of the second preparation module and so that the outlet of the first preparation module is positioned at a distance (d) from the intake of the second preparation module. - a first preparation module arranged in a first plane, - the first preparation module comprising a first surface and an opposing second surface and being delimited by first lateral faces, - the first preparation module further comprising an outlet arranged at the second surface of the first preparation module and an inlet, the inlet and the outlet being connected via a first microfluidic channel system, - the first preparation module comprising a first surface and an opposing second surface and being delimited by first lateral faces, - the first preparation module further comprising an outlet arranged at the second surface of the first preparation module and an inlet, the inlet and the outlet being connected via a first microfluidic channel system, - a second preparation module arranged in a second plane substantially parallel to the first plane, - the second preparation module comprising a first surface and an opposing second surface and being delimited by second lateral faces, - the second preparation module further comprising an intake arranged at the first surface of the second preparation module, wherein the intake comprises a blood separation filter, the intake being connected to a second microfluidic channel system, and wherein, - the first preparation module is connected to the second preparation module so that the second surface of the first preparation module is facing towards the first surface of the second preparation module and so that the outlet of the first preparation module faces the intake of the second preparation module and so that the outlet of the first preparation module is positioned at a distance (d) from the intake of the second preparation module. - the second preparation module comprising a first surface and an opposing second surface and being delimited by second lateral faces, - the second preparation module further comprising an intake arranged at the first surface of the second preparation module, wherein the intake comprises a blood separation filter, the intake being connected to a second microfluidic channel system, and wherein, - the first preparation module is connected to the second preparation module so that the second surface of the first preparation module is facing towards the first surface of the second preparation module and so that the outlet of the first preparation module faces the intake of the second preparation module and so that the outlet of the first preparation module is positioned at a distance (d) from the intake of the second preparation module.