The design and optimization of the energy harvester has been
presented previously [21]. The initial design was and made from
an acrylic box with Neodymium permanent magnets and achieved
a measured power output of 410 W at 0.1 g, 6.7 Hz acceleration
in a package less than 30 mm × 10 mm × 40 mm, for a normalized
power density of 7000 Wcm−3g−2. The device dimensions were
limited due to the application requirements. The designed dimensions
of the energy harvester are shown in Fig. 2 along with the
values for each dimension in Table 1. The coil has 1000 turns. In the
table, m is the mass of the levitating magnet and J is the strength of
the magnets.