Sensor power sources

Citation

(2010), "Sensor power sources", Sensor Review, Vol. 30 No. 3. https://doi.org/10.1108/sr.2010.08730caa.002

Sensor power sources

Article Type: Viewpoint From: Sensor Review, Volume 30, Issue 3

Both the opportunities, and the challenges, for sensors and sensor-enabled systems can be illustrated by this simple comparison: your home versus your car. Sensors in cars have proliferated, and by using them, every aspect of the car’s performance has been dramatically improved: safety, energy efficiency, passenger comfort, ease of operation and maintenance, and longevity. Homes have hardly any sensors, and the performance of homes has hardly advanced. The reasons are no great mystery: homes have much longer service lives, and so most of the stock is old; new homes are (generally) not built in a controlled factory environment; and home production does not get the economies of scale that the auto industry achieves, which supports R&D and makes sophisticated systems affordable. But the potential benefits of making our homes smarter are enormous, and not so different from the automotive case – energy saving, comfort and convenience, security and safety, healthier and more independent living.

Why are we not achieving these benefits? A key reason is the cost and inconvenience of installing, and maintaining, the sensor systems. But we were starting to move in the right direction. Wireless networking in homes is already commonplace, and these systems have become very easy for the average consumer to install. But consumers are undoubtedly reaching saturation point in terms of the number of gadgets they have to remember to recharge. If we try to add a few dozen sensors, or more, we would better have an improved approach to powering them. Luckily, as articles in this issue will show, this problem is being vigorously tackled on a whole range of fronts. Battery capacity, and thus lifetime, is an obvious one. Alternative high density energy storage methods are another, fuel cells in particular. Making recharging more convenient, by delivering power wirelessly, is also actively under development. Most of the sensors, we can imagine using in homes (and in other applications) will be at fixed points, and so the reason for not using mains power is installation cost, rather than mobility. This could enable novel approaches to power delivery.

Avoiding finite energy sources entirely is clearly attractive, and energy harvesting seeks to do just this. A range of ambient power sources can be harvested – motion and vibration, light and other radiation, temperature differences. The main challenge is to get the power levels to meet the demand, and this will depend at least as much on demand reduction as on increasing power levels. Sensors are consequently a very attractive prospect for powering by energy harvesting. Most sensor modules in current use have power demands far above any intrinsic limit, particularly where the data rates are low. However, power requirements are dropping rapidly. For example, wireless communication standards are being developed specifically for the low data rates and distances needed for networked sensors; this is likely to enable large power reductions.

Smart homes are just one application of many where the pervasive deployment of sensors has great potential benefits. Better solutions for powering these sensors are essential. Let us find them!

Eric Yeatman Department of Electrical and Electronic Engineering, Imperial College London, London, UK