Method and system for carrying out heterogeneous chemical or biological reactions, the method comprising the steps of providing an analytical device comprising at least one liquid processing unit, the liquid processing unit comprising at least one reaction chamber, and at least a first inlet channel in fluid communication with the reaction chamber, supplying to the reaction chamber via the first inlet channel or a second inlet channel analyte capturing particles, supplying to the reaction chamber via the first inlet channel or the second inlet channel a liquid sample containing at least an analyte of interest, confining by an equilibrium of forces the analyte capturing particles in a particle rearrangement zone comprised in the reaction chamber, said forces comprising a drag force Fd generated by liquids flowing through the first inlet channel and a counter-oriented force Fg, capturing analytcs present in the liquid sample with the particles in the particle rearrangement zone.