Functional device, in particular integrable into a trafficable pavement, comprising successively: - a first protective film, arranged on the front face of the device, made of a first material, - an internal encapsulation film, made of a third material, - a second protective film arranged on the rear face of the device, made of a fifth material, characterised in that said functional device further comprises: - a first external encapsulation film between the first protective film and the internal encapsulation film, the first external encapsulation film being made of a second material, - a second external encapsulation film between the internal encapsulation film and the second protective film, the second external encapsulation film being made of a fourth material, - one of the films, among the first external encapsulation film, the internal encapsulation film and the second external encapsulation film, coating active elements, the first material, the second material, the third material, the fourth material and the fifth material having Young's moduli E 1, E 2, E 3, E 4 and E 5, respectively, and coefficients of thermal expansion CTE 1, CTE 2, CTE 3, CTE 4 and CTE 5, respectively, E 1 and E 5 being similar or identical, E 2 and E 4 being similar or identical, E 1 > E 2 and E 4 < E 5, CTE 1 and CTE 5 being similar or identical, CTE 2 and CTE 4 being similar or identical, CTE 1 < CTE 2 and CTE 4 >CTE 5. - a first protective film, arranged on the front face of the device, made of a first material, - an internal encapsulation film, made of a third material, - a second protective film arranged on the rear face of the device, made of a fifth material, characterised in that said functional device further comprises: - a first external encapsulation film between the first protective film and the internal encapsulation film, the first external encapsulation film being made of a second material, - a second external encapsulation film between the internal encapsulation film and the second protective film, the second external encapsulation film being made of a fourth material, - one of the films, among the first external encapsulation film, the internal encapsulation film and the second external encapsulation film, coating active elements, - a first external encapsulation film between the first protective film and the internal encapsulation film, the first external encapsulation film being made of a second material, - a second external encapsulation film between the internal encapsulation film and the second protective film, the second external encapsulation film being made of a fourth material, - one of the films, among the first external encapsulation film, the internal encapsulation film and the second external encapsulation film, coating active elements, the first material, the second material, the third material, the fourth material and the fifth material having Young's moduli E 1, E 2, E 3, E 4 and E 5, respectively, and coefficients of thermal expansion CTE 1, CTE 2, CTE 3, CTE 4 and CTE 5, respectively, E 1 and E 5 being similar or identical, E 2 and E 4 being similar or identical, E 1 > E 2 and E 4 < E 5, CTE 1 and CTE 5 being similar or identical, CTE 2 and CTE 4 being similar or identical, CTE 1 < CTE 2 and CTE 4 >CTE 5.