Vertical capacitive energy harvester positively using contact between proof mass and electret plate - Stiffness matching by spring support of plate and stiction prevention by stopper mechanism

We proposed the vertical capacitive energy harvester using dielectric plate and polymer electret [1–3]. In this study, two methods to effectively use the contact between proof mass and electret; one is to match the stiffness between plate and mass, which is effective to increase their contact duration. For this purpose, instead of a gel for shock-absorber, a soft spring for supporting the plate is employed. Another is to study detach mass from their contact, opposing electrostatic attraction. We contrived a stopper mechanism. The output power was improved 5 times up to 50 µW when acceleration and frequency was 0.2 g and 18 Hz.