Biomedical Engineering Reference
In-Depth Information
addresses the feasibility of using body motion to power portable, wear-
able, or implantable systems, such as biomedical applications.
Kinetic or inertial energy harvesting uses external vibration or
motion to generate energy. This external vibration can be in the form
of engine or machine-based vibrations (constant frequency vibrations),
while motion can be associated with human activities, environment
movement, or oscillations with low-frequency, large amplitude, and
broad-frequency spectra. Energy scavenging from kinetic generators
uses the external vibration or motion to produce electricity. The kinetic
energy is transferred to a proof mass where several transduction techni-
ques can be employed to transform it to electrical energy. These
devices are typically designed to match their natural resonant fre-
quency with that of the energy source to maximize their power output.
Linear-based energy harvesters are found to be well suited for machine
vibrations because mechanical vibrations are relatively uniform (con-
stant frequency) with a main vibration axis.
Mechanical vibration has an energetic content in the form of kinetic
energy. A better estimation of the available energy leads to a better
match of energy harvesters for a given external source. One of the
questions that need to be solved is how much energy is available in
order to determine how it can be harvested. In order to solve that
question, the transduction generation (how to transform one form of
energy into another) needs to be analyzed to determine if there are
generation limits. Kinetic energy harvesting is studied later to define
the parameters that need to be considered for this evaluation.
On the other hand, the increasing use miniature low-power electronics
and wireless technologies for new medical monitoring applications, such
as body sensor networks for health monitoring (Hao and Foster, 2008;
Jovanov et al., 2005; Varshney, 2007), will challenge present technolo-
gies due to battery finite lifetime and size. A trade-off between battery
size and battery capacity has typically dominated the final size, lifetime,
and capabilities of a system.
The scavenging of body motion for powering portable mechanical
devices was first reported in 1770 when the Swiss watchmaker
Abraham Louis Perrelet
4
invented the self-winding mechanism for
Retrieved January 29 2013.
