A Micro-fabricated flexible and flat polyimide module with highly C-axis oriented AlN piezoelectric element for accurate vital signs monitoring

We report for the first time, a micro-fabricated flexible and flat aluminum nitride (AlN)/polyimide (PI) module enables to accurately monitor radial pulse and respiratory rate. Unlike previous studies, the 8-inch wafer micro-fabrication process does not significantly undermine the piezo-electrical effect of AlN due to its highly c-axis orientation, but maintains the module flexible and flat. As a consequence, the flat AlN/polyimide module with low stress is as flexible as polyvinylidene fluoride (PVDF), but has better MEMS processing capability. Moreover, no more post fabrication process such as polarization or complicated electrical packaging process is required for the module.