NON-INVASIVE SENSOR AND MEASURING METHOD

The invention relates to a method for measuring a parameter of interest in a target stratified medium (2) by means of a non-invasive sensor (1) based on photoacoustic detection or photothermal detection, the method comprising: a) providing a sensor comprising a light source (11a), a device for controlling a plurality of irradiation parameters of the source (11a), a detection cell (12), a memory storing a nomogram of nodal frequencies and an adaption module (14); b) the adaption module (14) chooses an initial model configuration of the target stratified medium (CMirrad) for a given irradiation; c) the processor of the adaption module (14) determines, in the nomogram of nodal frequencies, a plurality of nodal modulation frequencies and subsequently at least one particular modulation frequency (foptim) and finally a particular irradiation case comprising the at least one particular modulation frequency (foptim); d) the light source (11a) irradiates the target stratified medium (2) according to the particular irradiation case; e) the detection cell (12) detects an acoustic or thermal signal generated in response to the irradiation; f) the processor of the adaption module (14) determines the parameter of interest based on the detected acoustic or thermal signal.