Micro magnetic trap comprising a holder and a sample cell on said holder (5); means for providing a controllable homogeneous magnetic field (3) surrounding the sample cell; a modified micro-cantilever comprising a cantilever (1) having dimensions in the micron range and at least three paramagnetic microbeads with a diameter from 1 to 3 microns (2) attached to a bendable tip of the micro-cantilever such that they form a triangular arrangement; means for measuring the deflection of the micro-cantilever when the latter is in use (4). The trap does not require a specific surface functionalization in order to ensure an appropriate and selective linkage to a particular molecule.