The invention relates to a method for detecting microorganisms and/or the momentary activity status thereof by means of biosensors based on quorum sensing components as well as devices as biosensors for carrying out said method, to be used in biotechnology, environmental technology, and medical technology, for example. According to the invention, at least one ligand used for binding a receptor, or at least one receptor for a ligand, or at least one ligand used for binding a receptor and at least one receptor for said ligand or another ligand is/are chemically, physically, or biologically immobilized in some areas of a substrate surface. Physical or physical-chemical modifications caused by bonds of ligands that are emitted by microorganisms during the quorum sensing process to receptors can be measured.