A micromachined, high signal-to-noise ratio, acoustic emission sensor and its application to monitor dynamic wear

This paper presents a micro-machined, acoustic emission (AE) sensor, with a novel, corrugated PVDF sensing core. Using an improved fabrication process, a cost-effective sensing unit and more reliable device packaging method are presented. The curvatures of the stacked PVDF sensing layers, formed by a micro-embossing technique, using upper and lower dies of different geometries, are studied. The fabricated AE sensor is found to exhibit superior signal-to-noise ratio (SNR) and performs about 13 times better than a commercially available AE sensor, based on the results of a steel-ball drop test. The sensor is used to monitor the operation of ball bearings with different levels of wear. An experimental setup for producing ball bearings with different wear levels is also presented. Through frequency spectrum analysis, results are found to demonstrate its efficiency in detecting dynamic friction. This can be very useful in examining the condition of structures and predicting the likelihood of possible future failures.