The object of the invention is a device for detecting and/or determining the concentration of an analyte present in a tissue, comprising a sensor which is an optical fibre interferometer, one interferometer arm being coated with an immobilised binding agent enabling selective binding of the analyte present in the tissue, wherein said interferometer arm (5) coated with an immobilised binding agent is mounted inside a guide (30) enabling puncturing the tissue and performing an in situ measurement without the necessity to collect or prepare a sample, the guide (30) being provided with a closed guide face (31 ), longitudinal perforations (33) on sidewalls enabling the analyte to reach the binding agent, and an opening (32) in the input end (34) of the guide for introducing the interferometer (10) with the arm (5) coated with the binding agent into the guide (30), at the input end (34) of the guide, the opening (32) being sealed, enabling the isolation of the interior of the guide (30) from the surroundings, and the interferometer (10) being mounted in a position in which the interferometer (10) does not touch the inside walls of the guide. The object of the invention is also a method of detection and/or quantitative determination of an analyte present in a tissue by means of this device and use of this device for detecting and/or quantitative determination of an analyte present in tissue.
