building blocks of wireless sensor networks are the sensor nodes themselves.
For the last ten to twelve years a number of research institutions and
companies have been designing and producing nodes. However, the capabilities of
the resulting nodes vary widely, but only within certain bounds. All the nodes
have a number of features in common, i.e. a low power microcontroller, a low
power, short range, radio, a power supply and either on-board sensors, or the
capability to attach sensors. However, it is the variance within these bounds
that complicates application development.