Wireless sensor networks: Where are they?

The market for wireless sensor networks has yet to reach the multi-billion dollar levels predicted ten years ago. Sales of ZigBee chip sets, for example, are at most a few million per year. One reason for this smaller than expected market is that most sensor networks considered so far have usually been dedicated to a single task, such as environmental monitoring or energy management, and the resulting benefits often do not justify the cost of installing and maintaining the network. This should eventually change: the costs of sensors and motes will decline; batteries and energy scavenging techniques should improve; communication capacity and efficiency may increase; and, software and system management tools will hopefully improve.