A process for pre-concentration and detection of at least one single-stranded nucleic acid target molecule, the process comprising the steps of generating a flow of liquid comprising at least one magnetic nanoparticle in a micro-channel and a plurality of single-stranded nucleic acid probe molecules attached to the nanoparticle, generating an alternating magnetic field in the part of the micro-channel using an electromagnet, the magnetic field having an intensity and frequency that are suitable for causing magnetic hyperthermia of the nanoparticles so as to cause denaturing of the duplex formed by the single-stranded nucleic acid target molecule and the single-stranded nucleic acid probe molecule, and detecting the single-stranded target molecule dispersed in the liquid.