Biomedical Engineering Reference
In-Depth Information
CHAPTER
4
Power Consumption and Applications
Biomedical devices encompass a broad spectrum of applications; those
that require power and those that not. These devices range from con-
tact lenses, bone implants, stents, surgical instruments, cardiac pace-
makers to blood glucose monitors. Powered biomedical equipment has
relied on the power grid and/or batteries for operation due to the
power requirement of devices. As medical technology evolved, devices
decreased in size and became portable and even implantable such as
pacemakers. Within implantable medical devices (IMDs), they can be
divided into passive (structural devices) or active devices (powered
devices).
Table 4.1
provides a reference for the power requirements of
several powered devices. At the same time, biomedical equipment has
different power requirements.
There are new promising technologies for health-care monitoring:
wireless body area networks and wireless personal area. Thus, actual
power sources will be challenged even more with the increasing use of
wireless communications. Wireless communications are still con-
strained with the unwieldy wires for tethered connections between the
sensors and the central unit, and the implementation of energy-aware
communication for wireless protocols (Jovanov et al., 2005). For
example, the use of Bluetooth standard employing two AA batteries
can function for 1
7 days (wake up time
B
3 s, 700 kbps data rate,
7 nodes, 10 m range), while the use of the ZigBee wireless standard
Table 4.1 Orders of Magnitude of Power Requirements
Equipment
Power (W)
10
2
Powered exoskeleton
B
Powered prosthesis
B
10
Retinal stimulator
10
2
1
B
B
10
2
2
Neural recording
10
2
3
Analog cochlear processor
B
B
10
2
4
Hearing aid
10
2
5
Pacemaker
B
B
10
2
6
Wristwatch
