The windmill is a beautiful artifact and very recognizable in the Dutch landscape. It converts wind energy into rotational motion, and is one of the earliest energy harvesters in history. Today, research on energy harvesting is not only focussing on generating megawatts of electrical power, but also deals with micropower harvesters that can for example be used to power small wireless sensors or RFID tags.
Micopower energy harvesters can convert energy from the environment (vibrations, thermal difference, solar, RF) into electrical energy that can be stored in a capacitor or battery.
This allows wireless sensors to transmit their payload once the harvester has collected enough energy. Thus, in principle, the wireless sensor can have an infinite lifetime. Of course, the amount of energy that can be harvested depends on the application. One of the reasons why micropower scavenged wireless sensors are not yet widely used today is that current radio solutions such as ZigBee or Bluetooth consume (much) more power than the harvester can deliver.
A promising solution for this problem is to use Ultra-WideBand communication. UWB radio makes use of carrierless, short duration pulses to transfer the information. Since the radio can be switched off during the time laps between two pulses, the average power consumption can be low enough so that it can be combined with an energy harvester. That’s why in this group we are working on energy scavenged UWB radios since they seem to be the perfect match. Another distinct advantage is that UWB communication can offer accurate localization within a few cm’s. This means that finding your missing car, laptop or wife will be a piece of cake without ever having to change the radio battery!
Mark Stoopman
