Biomedical Engineering Reference
In-Depth Information
10000
1
000
Combustion
Engines
100
Direct Methanol
Fuel Cell
Electromagnetic
Generators
1
0
PEM Fuel Cell
Photovoltaic Cells
1
Thermoelectric Generators
1
1000
100
0.1
10
Human
Body
0.1
Specific Power (W/liter)
Figure 1.2 Comparison of power sources. Chart adapted from Flipsen (2006).
use the energy harvesting approach. However, larger generator volumes
can produce higher power outputs. Continuing with the reference of
1mW/cm
3
, a relatively small generator with a volume of 10 cm
3
could
produce up to 10 mW. According to the chart in
Figure 1.3
,10mWcan
be used to power some remote controls and communication devices
(pagers). Taking as a reference the shoe generator presented by
Kymissis et al. (1998) with a power generation over 200 mW, some
radios and cell phones can be powered by energy harvesting.
Figure 1.3
describes the power requirements of several electronic
products ranging from medical devices to consumer products (power
consumption from 1
W up to several watts). This figure also includes
the power output of one energy harvester (a shoe generator) and sev-
eral human-operated generators for comparison purposes. Although
human-operated generators have a power output enough to energize
power-hungry devices (such as notebook computers),
μ
they require
active generation.
On the other hand, passive generation, although producing a lower
power output, produces an adequate amount to energize low-power
electronic applications, including some medical devices. Therefore, it is
