A non-destructive inspection device for detecting flaws in a body of composite material, comprising: - a first structural layer , having a first and a second surface opposite each other; - a second structural layer mechanically coupled to the first surface of the first structural layer ; - a sealed chamber , extending between the first and the second structural layer, containing a gas; - an active region , housed in the chamber , having a first and a second conduction terminal , and being made of one of the following materials: partially reduced graphene oxide, reduced graphene oxide, graphene; and - a voltage generator coupled to the first and second conduction terminals of the active region , operable to generate, in a first operating condition, an AC electric current between the first and second conduction terminals of the active region so as to produce, by means of thermoacoustic effect, a first acoustic wave (W E ) propagating away from the chamber , wherein said chamber is configured to receive, in a second operating condition, a second acoustic wave generated by a reflection of the first acoustic wave; and wherein said active region is configured to generate, in the second operating condition and by thermoelectric effect, an electrical signal between the first and second conduction terminals of the active region , characterized in that the second structural layer is an integral part of said body , which is formed of a plurality of superposed layers of composite material bonded together by resin, both the first and the second structural layers being made of the same composite material as said body . - a first structural layer , having a first and a second surface opposite each other; - a second structural layer mechanically coupled to the first surface of the first structural layer ; - a sealed chamber , extending between the first and the second structural layer, containing a gas; - an active region , housed in the chamber , having a first and a second conduction terminal , and being made of one of the following materials: partially reduced graphene oxide, reduced graphene oxide, graphene; and - a voltage generator coupled to the first and second conduction terminals of the active region , operable to generate, in a first operating condition, an AC electric current between the first and second conduction terminals of the active region so as to produce, by means of thermoacoustic effect, a first acoustic wave (W E ) propagating away from the chamber , wherein said chamber is configured to receive, in a second operating condition, a second acoustic wave generated by a reflection of the first acoustic wave; and wherein said active region is configured to generate, in the second operating condition and by thermoelectric effect, an electrical signal between the first and second conduction terminals of the active region , characterized in that the second structural layer is an integral part of said body , which is formed of a plurality of superposed layers of composite material bonded together by resin, both the first and the second structural layers being made of the same composite material as said body . wherein said chamber is configured to receive, in a second operating condition, a second acoustic wave generated by a reflection of the first acoustic wave; and wherein said active region is configured to generate, in the second operating condition and by thermoelectric effect, an electrical signal between the first and second conduction terminals of the active region , characterized in that the second structural layer is an integral part of said body , which is formed of a plurality of superposed layers of composite material bonded together by resin, both the first and the second structural layers being made of the same composite material as said body . <EOS>