Environmental Engineering Reference
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Beeby et al. [103], the earliest example of a piezoelectric kinetic energy har-
vesting system extracted energy from impacts. Umeda et al. [104] pioneered
the analysis of the energy generated by the impact of a steel ball on a piezo-
electric membrane. Initial work explored the feasibility of this approach by
dropping a 5.5-g steel ball bearing from 20 mm onto a piezoelectric trans-
ducer. Keawboonchuay et al. [105] studied a high-power impact piezoelectric
generator that can be incorporated into ammunitions. Subsequently, impact
coupling of a piezoelectric transducer designed for use in human applications
was described by Renaud et al. [106]. The authors presented some analysis
related to the impact harvester, which was comprised of an inertial mass
confined within a frame but free to slide along one axis, for human applica-
tions and assessed the relevance of such a system for harvesting energy from
large-amplitude and low-frequency excitations. Energy is generated when the
sliding mass strikes steel/PZT (lead zirconate titanate) cantilevers located at
each end of the frame. Several studies on direct straining of, or impacting
on, a piezoelectric element for human applications have also been reported.
One of the earliest examples of a shoe-mounted generator incorporated a hy-
draulic system mounted in the heel and sole of a shoe coupled to cylindrical
PZT stacks [107]. The hydraulic system amplifies the force on the piezoelec-
tric stack whilst reducing the stroke. A subsequent device was developed at
the Massachusetts Institute of Technology (MIT) in the 1990s [81] as an in-
sole in a sports training shoe; the bending movement of the sole strains both
polyvinylidene fluoride (PVDF) stacks to produce electrical power.
4.1 Impact-Based Vibration Energy Harvesting (VEH) Using
a Piezoelectric Push-Button Igniter
A self-powered push button is an interesting application that utilizes impact-
based energy harvesting [28] for powering a self-powered remote controller.
In 1956, Robert Alder designed a self-powered remote control called the Space
Commander for Zenith televisions. It featured a set of buttons that struck
aluminum rods to produce ultrasonic waves when decoded at the television
receiver would change channels appropriately. Joe Paradiso and Mark Feld-
meier took this theme further in 2001 by using a piezoelectric element with
aresonantly matched transformer and conditioning electronics that, when
struck by a button, generate electrical power to run a digital encoder and
a radio transmitter [108]. Furthermore, a German company, EnOcean [109],
developed some self-powered radio transmitters, energized by a bi-stable
piezoelectric cantilever that snaps when pressed, and are conditioned by a
switching voltage regulator. In this impact-based VEH research, the proposed
piezoelectric push-button igniter system, as depicted in Figure 4.2 , is designed
to be compact, simple, low cost in terms of power density and energy require-
ments, and at the same time able to harvest sufficient energy from the impulse
force generated by human pressing to power the remote controller.
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