Abstract: The invention relates to a microelectronic sensor device with a matrix array of rows (R4, R5) and columns (C1, C2) of detection cells (10), wherein each detection cell comprises an activation element (30) for transferring target particles (e.g. magnetic beads) into an activated state and a sensor element (20) for detecting activated target particles. According to a preferred embodiment, the activation elements (20) of each row of the matrix as well as the sensor elements (20) of each column of the matrix are connected in series. By activating one row and reading out one column, each detection cell (10) can thus individually be addressed with a limited number of column- and row-address circuits.