Development of structure enhanced micromachined acoustic emission sensors with wide-bandwidth and improved sensitivity

This paper presents an innovative polymer-based micromachined acoustic emission (AE) sensor. By using the developed micro-embossing fabrication method, the multi-layer piezoelectric polymer (PVDF) thin films with electrodes and dielectric interfaces can be structured as a wavy shaped sensing core element. The core element is then integrated with the novel micromachined epoxy detection-head and being packaged to form the AE sensor. The characteristics of the device include: (1)The wavy shaped sensing element increases the operation bandwidth and effectively absorb acoustic waves to improve the sensitivity. (2)Structured multi-piezoelectric layers are electrically connected-in-parallel, which increases the charge amount and signal to noise ratio. (3)The packaged wavy shaped structure serves as the spring with sufficient stiffness to couple with acoustic emission signals. (4)Microfabrication process allows the wavy shaped structure with adjustable curvature design and mass production. The detailed fabricated process and packaging method as well as experimental results are described in the text.