Nodes in wireless sensor networks (WSNs) typically
have limited power supply and networks are often expected to be
functional for extended periods. Therefore, the minimization of
energy consumption and the maximization of network lifetime are
key objectives in WSN. This paper proposes an overlay, energy
optimized, sensor network to extend the functional lifetime of an
energy-intensive sensor network application. The overlay network
consists of additional nodes that exploit recent advances in energy
harvesting and wake-up radio technologies, coupled with an application
specific, complementary, ultra-low power sensor. The experimental
results and simulations demonstrate that this approach can
ensure survivability of energy-inefficient sensor networks. Simulating
applications using energy-intensive video cameras and air
quality sensors, combined with the proposed overlayed ultra-low
power sensor network, demonstrates that this approach can increase
functional lifetime toward perpetual operation and is suitable
for WSN applications in which complementarity exists between the
required energy-intensive sensors and low-cost sensors that can be
used as triggers.