Sensors Empower the "Internet of Things"

EDN (Conner) - The "Internet of Things" is the networked interconnection of objects-from the sophisticated to the mundane-through identifiers such as sensors, RFID (radio-frequency-identification) tags, and IP (Internet Protocol) addresses. Ford's Tool Link system, for example, builds sensors into vehicles, including the Ford Transit Connect, so that when the driver presses a button, the dashboard displays an inventory of all onboard tools. A similar system for homes would show you an inventory of all clothes that are supposedly in your suitcase or objects in your briefcase.

Combining the number of infrastructure sensors with the number of sensors in personal devices, such as cell phones, yields a round number of 1000 sensors per person that manufacturers will develop and deploy over the next 10 years. With a world population in the billions, this figure would translate to more than 1 trillion sensors. That many sensors collecting data implies a lot of data manipulation, which in turn implies a computing cloud-that is, the use of large numbers of computers, often over distributed data centers, to seamlessly process and store large amounts of data. At a typical data rate, 1 million sensors running 24 hours a day would require 50 hard disks running in parallel to capture the 20 petabytes of data these sensors would create in just six months. Companies that are already deep into cloud computing are jumping into the Internet of Things as a significant new business opportunity for their expertise. Two notable examples are IBM, with its Smarter Planet program, and Hewlett-Packard, with its CENSE (Central Nervous System for the Earth).


Although the cost of large-volume silicon hardware does tend toward zero over time, there's more to a sensor node than the silicon. Wireless-sensor nodes have four general components: the sensor and its signal-conditioning circuit, the microcontroller, a radio transceiver, and a power source. The first three components benefit from Moore's Law and rapidly grow in capability while dropping in price. However, the power source doesn't rely on silicon integration and receives no such benefit. Whereas batteries, supercapacitors, and energy-harvesting devices have seen significant improvement over the past several years, energy storage and harvesting do not in general benefit from economies of scale. The power available is still about the same with a fixed budget on the order of milliwatts. The rest of the sensor nodes can now do more with that fixed power budget, however. Nonetheless, dedicated wireless-sensor nodes-for the near term at least-will have a formidable price hurdle to overcome...