FIELD: medicine.SUBSTANCE: group of inventions relates to medical equipment. Sensor system for detecting the analytes contains a substrate, a magnetometer and magnetic particles. At least one sensor associated therewith. Magnetometer adjoins the hydrogel sensor. Magnetic particles are associated with a hydrogel sensor. Magnetic fields of magnetic particles are aligned in one direction. Working distance at which magnetic fields can be detected by a magnetometer is in the range of tens of microns to at least two millimeters from the magnetic particles. Sensor sheath for detecting analytes comprises a substrate, associated with it at least one hydrogel sensor with magnetic particles, a magnetometer and an electronic unit coupled to the hydrogel sensor. Substrate is adapted to be attached to the catheter.EFFECT: it is possible to create a resulting stable magnetic field that extends over a few millimeters from the magnetic particles and does not require the application of any external magnetic fields.16 cl, 18 dw
