A method and systems for locating a source of particles, molecules, or fragments of molecules using particle, molecule, or fragment of molecule reception rate is disclosed. According to the invention, the particle, molecule, or fragment of molecules diffusion parameters in the search space are determined and a lattice is designed on the search space. After having determined whether or not at least one particle, molecule, or fragment of molecule is detected by a sensor, a probability is computed for each node of said search space lattice. The probability associated to each node of the search space lattice corresponds to the probability that the particle, molecule, or fragment of molecule source is located on the node. Then, the move of the sensor is evaluated according to the entropy of the computed probabilities.