Environmental Engineering Reference
In-Depth Information
4.1.4
Summary
In this impact-based VEH research, special interest is placed on using a
piezoelectric push-button igniter as the energy harvester because it is easy
and simple to harvest mechanical force energy from human beings. An en-
ergy harvesting circuit design for the piezoelectric push-button generator
was proposed and implemented efficiently for a wireless RF transmitter. This
self-powered wireless transmitter is capable of transmitting a 12-bit digital
word information using the mechanical force energy of 15 N harvested from
depressing the push button attached to the energy harvesting circuit. Experi-
mental results showed that when the piezoelectric push button is depressed,
67.61
Jofelectrical energy is harvested, and it is sufficient to transmit infor-
mation for at least 2 complete 12-bit digital words via the RF transmitter unit,
which consumes 26.4
Jofenergy for 1 digital word transmission. As such,
this research work has successfully demonstrated the feasibility of a com-
pletely self-autonomous piezoelectric push-button wireless RF transmitter,
which optimizes effectiveness in size, weight, and cost.
4.2 Impact-Based VEH Using Prestressed Piezoelectric
Diaphragm Material
Cabling has always been a hassle for applications like the design of a house's
lighting system with the need to draw cables from lamps and bulbs to the
switches mounted on the walls of the house. The need for in-wall cabling will
often result in high costs for the homeowner. Undesirable recabling impli-
cations may also arise over time should the cable become faulty. Other than
that, the conventional method to power onboard wireless communication and
electronic circuitries of the controllers are normally alkaline or rechargeable
batteries. One major drawback with these commercially available battery-
operated remote controllers is that batteries have a limited energy supply.
Every time the remote controllers operate, the energy level of the internal
battery source depletes, until some time later when the controllers are no
longer able to function. As such, regular maintenance of the controllers is re-
quired in order to not create any disruption to the user. To address this issue,
an impact-based energy harvesting system using a piezoelectric igniter has
been carried out as discussed in Section 4.1. It is a simple and viable solution
to harvest mechanical force energy from human beings to sustain the opera-
tion of the remote controller. Whenever someone depresses the push-button
mechanism, a high-impact force coming from the internal hammer strikes
onto the piezoelectric material, which consists of a stack of piezoelectric ce-
ramic layers, and some electrical energy is generated. However, under this
high-stress cycling, it is mentioned by Kim et al. [114] that the piezoelectric
material stack of the push-button igniter may develop interfacial cracking
or buckling, thus shortening its lifetime. In addition, the piezoelectric igniter
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