Acoustic Emission Sensors using Silicon Mechanical Resonators

Abstract

Ultrasonic sensors using cantilever beam and free-free beam resonators are designed and fabricated for acoustic emission (AE) sensing. The sensors are operated under the resonant conditions and the generated oscillation is detected by silicon piezoresistors. In order to investigate the air friction of the resonators, the quality factors are measured as a function of pressure. The sensitivities of the two resonators are compared. The cantilever beam resonator is vacuum-packaged by glass-silicon anodic bonding and the AE sensing test is carried out by the method of breaking pencil lead. The response time of the vacuum packaged sensor is also measured.