Biomedical Engineering Reference
In-Depth Information
battery replacement (Flipsen et al., 2004). Implantable neurostimulators
and infusion pumps have larger power consumption and have longevity
of 3
5 years (Paulo and Gaspar, 2010). Longer battery lifespan is
always desired because it reduces medical care costs for surgically
implantable devices. It also makes it possible to add more functionality
or more frequent measurement of physiological parameters for a given
battery duration.
1.1 TECHNOLOGY TREND
Computer technology has progressed aggressively over the last two
decades as shown in
Figure 1.1
, but it is also clear that battery technol-
ogy has not kept the same pace. This energy source, although
increased in capacity over the years, seems to slow down the progress
for portable electronics to gain a wider adoption. It is evident that
advances in computational capabilities outpace the battery develop-
ment; hence, more applications could be envisioned if batteries fol-
lowed the trend of computer technology. For instance, the cost of
battery replacement prohibits a wider deployment of wireless sensor
networks. As a result, other energy sources are needed to cover the
increasing demands of new electronic applications. Energy harvesting
can be an option to solve this problem.
Figure 1.1
represents the increase in performance for several tech-
nologies compared against those available in 1990; for instance, disk
capacity increased by a factor of 10,000 between 1990 and 2010 while
10,0000
Disk capacity
Laptop CPU speed
Availabe RAM
Wireless network speed
Battery energy density
10,000
1,000
100
10
1
1990
1992
1994
1996
1998
2000
2002
2004
2006
2008
2010
Year
Figure 1.1 Electronics trend since 1990 (Romero, 2010; Starner and Paradiso, 2004).
