Figure 1 summarizes the various alternatives for scavenging energy from environmental sources. All of these are attractive sources depending upon the specific condition and requirements. It is quite obvious from this figure that there is significant possibility of harnessing the unused energy and that is the underlying thought behind the CEHMS. The technological concept addressed by CEHMS will have a huge impact on our lives.

Figure 1: Comparison of various potential power sources for power source.

Several applications can be cited that will be directly influenced by the research conducted at the CEHMS. For example - one of the major questions facing the wireless sensor industry is “How to power the sensors?” “Who will replace billions of batteries?” The powering of the densely populated sensor nodes in a network is a critical problem due to the high cost of wiring and replacing batteries. In many cases, these operations may be prohibited by the infrastructure. In order for the nodes to be conveniently placed and efficiently utilized, they should be as small as possible, which puts an upper limit on their life time. If an electronic device with a 1 cm³ of non-rechargeable lithium battery (at maximum energy density of 2880 J/cm³ or 800 watt hour per liter) were to consume 100 µW of power on average, the device would last 333 days. A lifetime of approximately one year is not practical. Although the nodes in the wireless network will be much smaller than 1 cm³, the power requirements will force them to use a battery of much larger size increasing the system volume. Harvesting the energy available locally may supplement the battery or even replace them.

Thus, the development of multi-scale energy harvesters will solve critical problem facing the sensor industry in the implementation of the wireless networks and open the possibility of several autonomous self – powered applications including industrial health monitoring, condition based maintenance, perimeter security nets, border intrusion sensor nets, micro-robotic vehicles and UAV’s, aircraft structural health monitoring, and implantable medical devices.