Energy harvesting in aeronautics for battery-free wireless sensor networks

In recent years, wireless sensor networks (WSN) have been considered for various aeronautical applications, including, among others, structural health monitoring (SHM) and fiight-tests. Each network node would allow performing sensing, data processing, and wireless transmission of information. Thus WSN permit (often new) functions without the need of adding extra wiring to an already large burden. However, these nodes need to be self-powered, many of the advantages of wireless sensor networking being lost if external (i.e. wired) power sources were used. For this purpose, batteries offer a high energy density at low cost. However, there are critical drawbacks associated with the use of batteries. First, environmental concerns and economical aspects associated with the replacement of primary batteries. Second, batteries may be prohibited since the wireless nodes are often implemented in locations without temperature regulation that could result both in a drastically reduced yield together with safety issues. Fortunately, batteries can be avoided through the use of environmental energy capture allowing a solution for long term, deploy and forget, WSN. However, environmental energy transducers, unlike batteries, are not energy reservoirs, and energy buffer storage is mandatory whatever the context. In this article we present hands-on experience related to ongoing - or prospective - implementations of energy harvesters in airliners.