Photoacoustic detecting device for measuring a parameter of interest in a medium comprising: ➢ A housing comprising a baseplate and a cover , ➢ A light source , configured to emit a light signal ➢ A photoacoustic cell comprising a hollow contact surface , emerging out of an aperture of the baseplate , said hollow contact surface being intended to be in contact with the medium, wherein the light signal is able to propagate in the photoacoustic cell and pass through the hollow contact surface to reach the medium, ➢ A guiding element , configured to direct the light signal toward the photoacoustic cell , ➢ A transducer linked to the photoacoustic cell and configured to detect a generated signal, where the generated signal is generated in the photoacoustic cell by a photothermic effect in the medium in response to an irradiation of the medium by the light signal, ➢ A first maintaining element configured to assemble the light source and the guiding element in a building block, said building block being housed in the housing Characterised in that ➢ The photoacoustic cell is reversibly attached to the building block by at least one fixing element accessible from an outside of the housing , in that a size of the photoacoustic cell is such that the photoacoustic cell can be removed from the housing by passing through the aperture of the baseplate when needed, and in that ➢ The transducer is reversibly coupled to the building block and placed between said building block and said photoacoustic cell , such that the transducer can be removed from the aperture of the baseplate at the same time or after the photoacoustic cell is being or has been removed from the housing . ➢ A housing comprising a baseplate and a cover , ➢ A light source , configured to emit a light signal ➢ A photoacoustic cell comprising a hollow contact surface , emerging out of an aperture of the baseplate , said hollow contact surface being intended to be in contact with the medium, wherein the light signal is able to propagate in the photoacoustic cell and pass through the hollow contact surface to reach the medium, ➢ A guiding element , configured to direct the light signal toward the photoacoustic cell , ➢ A transducer linked to the photoacoustic cell and configured to detect a generated signal, where the generated signal is generated in the photoacoustic cell by a photothermic effect in the medium in response to an irradiation of the medium by the light signal, ➢ A first maintaining element configured to assemble the light source and the guiding element in a building block, said building block being housed in the housing Characterised in that ➢ The photoacoustic cell is reversibly attached to the building block by at least one fixing element accessible from an outside of the housing , in that a size of the photoacoustic cell is such that the photoacoustic cell can be removed from the housing by passing through the aperture of the baseplate when needed, and in that ➢ The transducer is reversibly coupled to the building block and placed between said building block and said photoacoustic cell , such that the transducer can be removed from the aperture of the baseplate at the same time or after the photoacoustic cell is being or has been removed from the housing . <EOS>