Acoustic emission sensor with structure-enhanced sensing mechanism based on micro-embossed piezoelectric polymer

This paper presents an innovative polymer-based micromachined acoustic emission (AE) sensor. Using a novel micro-embossing fabrication method, a piezoelectric sensing core element is constructed with multi-layer polyvinylidene fluoride (PVDF). The multi-piezoelectric layers of corrugated surface geometry are connected electrically in parallel to increase the amount of charge and the signal to noise ratio. The core element is integrated with an epoxy detection head and packaged to form an AE sensor. Experimental results show the developed AE sensor possesses wide operational bandwidth (10 kHz to 1.4 MHz or more) and good displacement sensitivity. To verify the applicability of the sensor, a drilling experiment is performed with the sensor physically attached to a laminated multi-layer workpiece during drilling. Captured AE data allows clear recognition of drill touch-down and of each laminated layer when the drill penetrates the workpiece. The presented AE sensor fabrication technology exhibits the potential for production of high-resolution low-cost transducers for industrial applications.