2017 Volume 16 Issue 4 Pages 295-300
Electret condenser sensors (ECS) is suitable for detection of ultrasounds propagating air and soft materials because it has an air gap in the element. In this study, ECS were fabricated to detect artificial acoustic emission (AE) propagating a wood plate and AEs at a trunk of acerola. ECS demonstrated the higher S/N ratio from 40 to 100 kHz for the detection of the artificial AEs than a piezoelectric AE sensor (PS) and a wideband acceleration sensor (AC). The AEs detected by ECS showed several frequency peak from 50 to 200 kHz at the AE measurement at a trunk of acerola while the AE detected by PS also showed wide frequency from 100 to 500 kHz. Furthermore, the ECS had the same degree of sensitivity as PS at AE measurement at the trunk of acerola while AC hardly detected the AEs. The AE behavior of ES, however, did not partially coincide with the significant increase of AE events of PS. Hence, the long-term reliability of ES must be investigated for practical use of AE measurement of woody plants.
