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{{primary sources|date=February 2015}}
[[Image:Sensornode.svg|thumb|300px|The typical [[Computer architecture|architecture]] of the sensor node.]]
A '''sensor node''' (also known as a '''mote''' in [[North America]]), consists of an individual [[Node (networking)|node]] from a [[sensor network]] that is capable of performing a desired action such as gathering, processing or communicating information with other connected nodes in a network.
==History==
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===Power source===
A wireless sensor node is a popular solution when it is difficult or impossible to run a mains supply to the sensor node. However, since the wireless sensor node is often placed in a hard-to-reach ___location, changing the battery regularly can be costly and inconvenient. An important aspect in the development of a wireless sensor node is ensuring that there is always adequate energy available to power the system.
The sensor node [[Power consumption|consumes power]] for sensing, communicating and data processing. More energy is required for [[data communication]] than any other process. The energy cost of transmitting 1 Kb a distance of {{convert|100|m|ft}} is approximately the same as that used for the execution of 3 million instructions by a 100 million instructions per second/W processor.{{citation needed|date=March 2020}} Power is stored either in batteries or capacitors. Batteries, both rechargeable and non-rechargeable, are the main source of power supply for sensor nodes. They are also classified according to electrochemical material used for the electrodes such as [[Nickel-cadmium battery|NiCd]] (nickel-cadmium), [[Nickel-zinc battery|NiZn]] (nickel-zinc), [[Nickel-metal hydride battery|NiMH]] (nickel-metal hydride), and [[Lithium-ion battery|lithium-ion]].
Current sensors are able to renew their energy from [[Solar energy|solar]] sources, Radio Frequency(RF), [[Thermogenerator|temperature]] differences, or [[Vibration powered generator|vibration]]. Two power saving policies used are [[Dynamic Power Management]] (DPM) and [[Dynamic Voltage Scaling]] (DVS).<ref>Dynamic Power Management in Wireless Sensor Networks, Amit Sinha and Anantha Chandrakasan, IEEE Design & Test of Computers, Vol. 18, No. 2, March–April 2001</ref> DPM conserves power by shutting down parts of the sensor node which are not currently used or active. A DVS scheme varies the power levels within the sensor node depending on the non-deterministic workload. By varying the voltage along with the frequency, it is possible to obtain quadratic reduction in power consumption.
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