**3. Results**

This work was aimed at evaluating the protective and barrier behavior of di fferent selected polymeric coatings for flexible piezoelectric energy harvesting devices in liquid flows, in particular in a seawater environment. The application and the type of micro-devices required specific characteristics for the coatings, i.e., flexibility, conformability, ease of application, besides properties related to the insulating, waterproof and barrier behavior.

As already discussed, parylene-C, PMMA, PDMS and PDMS-PVDF were selected as coating materials to be tested, each characterized by di fferent thicknesses: 2.7 μm for parylene, ~3 μm for PMMA, ~100 μm for PDMS and PDMS-PVDF. Di fferently from the other coatings applied by dip-coating, parylene C was deposited by CVD, so the thickness of the resulting coating was much more controllable.
