Self-powering sensors

Citation

Jones, G. (2001), "Self-powering sensors", Sensor Review, Vol. 21 No. 2. https://doi.org/10.1108/sr.2001.08721baa.002

Self-powering sensors

Self-powering sensors

Gordon Jones

Keywords: Autonomy, Sensors

The growth in new approaches to sensing and monitoring over recent years has been considerable, encompassing such techniques as optical fibre sensors, tomography, sensor arrays, etc. This growth has been led by the simultaneous advances in signal processing methodologies for extracting deeper levels of information and improved prognostic possibilities. The area of smart sensors has seen the emergence of self-checking and self-calibrating sensors.

In this issue of Sensor Review, yet another emerging sensing domain is addressed. Namely, a group of sensors that is capable of converting one form of power into another for sensing purposes. There are several examples of such sensing systems, many of which are reviewed in the article "Self-powered systems: a review of energy sources" in this issue. A major aspect which distinguishes these sensing systems is their utilisation of conveniently available energy, i.e. from mechanical vibrations at levels which may be relatively low for many power conversion applications but not so for sensing and data transmission applications.

One category of self-powering sensors relates to sensors which may be regarded as autonomous in the sense that they are only activated when the energy to drive them is available and the measurand itself is associated with that energy.

An early, if somewhat primitive, example of such a sensor is the photovoltaic light meter.

This converted the optical power incident on a photosensitive element into electronic voltage that operated an electromagnetically driven pointer to indicate the intensity of the incident light. No external energy source, such as a battery, was involved. More recent examples of such autonomous sensors include:

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  Miniature stand-alone transducers, which are activated by stressing a piezoelectric element that, in turn, provides the electrical power to measure and then transmit the data.

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  Systems for measuring electric currents on high voltage networks, which draw their energisation via electromagnetic induction from the current to be measured on the high voltage line. This power is also used to activate an optical fibre link for transmitting the data to a ground control and overcome electrical insulation problems.

The emergence of such autonomous sensing systems provides new opportunities for embedding sensors, which remain dormant until triggered by events that they are designed to monitor. As such, they can prove to be cost-effective, non-intrusive and may be deployed to form multisensor systems with intercommunication. They also lead to interesting questions of self-validation, to distinguish between dormancy and faulty non-activation.

It is clear that a range of new members for the power conversion group of sensors is likely to emerge over the next few years. Questions of how best to deploy, self-check, range of applicability, etc. will arise and these will present the challenges to be met, if widespread commercialisation of such systems is to ensue.