A photo-acoustic gas sensor is disclosed. The photo-acoustic gas sensor includes a substrate, a light emitter unit supported by the substrate, the light emitter unit including a light emitter configured to emit a beam of light pulses with a predetermined repetition frequency and wavelength corresponding to an absorption band of a gas to be sensed, and a detector unit supported by the substrate, the detector unit including a microphone, wherein the beam of light pulses traverses an area intended to accommodate the gas and the microphone can receive a signal oscillating with the repetition frequency.