“…Currently, several candidate sensor technologies suitable for SHM application have been widely investigated through lab-scale experiments. They include active and passive piezoelectric transducers, e.g., lead zirconate titanate (also called PZT) ceramics [ 4 , 5 , 6 ], fiber-optic and Fiber Bragg Gratings (FBG) [ 7 , 8 ], strain gauges [ 9 , 10 ], comparative vacuum monitoring (CVM) [ 11 , 12 ], and foil eddy current sensors [ 13 , 14 ]. Some of the SHM technologies have matured in recent years, allowing them to be tested during full-scale fatigue tests and experimental flights, or have already been installed in civil airplanes in service (FBG, CVM, PZT).…”