Functional device integrated into a traversable surface and method for producing a traversable surface with same

A functional device comprising successively:

• a first protective film, arranged on a front face of the device, consisting of a first material;
• a first external encapsulation film, consisting of a second material;
• an internal encapsulation film, consisting of a third material;
• a second external encapsulation film, consisting of a fourth material;
• and
• a second protective film arranged on the rear face of the device, consisting of a fifth material;
• the internal encapsulation film fully coating active elements,
• the first material, the second material, the third material, the fourth material and the fifth material having Young's moduli E1, E2, E3, E4 and E5, respectively, and coefficients of thermal expansion CTE1, CTE2, CTE3, CTE4 and CTE5, respectively,
• wherein
• E1 and E5 are similar or identical,
• E2 and E4 are similar or identical,
• E1>E2 and E4<E5,
• CTE1 and CTE5 are similar or identical,
• CTE2 and CTE4 are similar or identical,
• CTE1<CTE2 and CTE4>CTE5,
• E2>E3 and E3<E4 and
• CTE2<CTE3 and CTE3>CTE4.