The invention relates to the test device for platelet aggregation detection comprising: —an element (1) for receiving a blood sample—a capillary tube (3) connected at a first end (31) to said element (1) and at a second end (32) to a pressure lowering device (5) to pump said blood sample through said capillary tube (3)—at least a pair of facing electrodes (8) on the capillary tube—a device for measuring an impedance between said pair of facing electrodes. The invention also relates to a process for using this device, comprising: a) receiving a blood sample and pumping it through the capillar tube (3) b) determining a dynamic change of the value of the impedance between at least one pair of electrodes (8).