Micropower Wireless Strain Sensor for Rotorcraft Applications

Advances in energy harvesting wireless sensors holds promise for next generation strain and loads tracking of critical rotorcraft components. Miniaturization of these sensors depends, to a great extent, on the amount of energy they require to track static and dynamic loading events. As the energy consumption is reduced, the demands on the energy harvester are also reduced, which allows the harvester to be smaller, lighter, and less complex. Prior work has shown that a wireless strain sensor node's energy consumption is directly related to the sampling frequency used for a given application. However, when the sampling rates are reduced too aggressively, or if duty cycling is used, the peak strains may be underestimated or missed entirely. This work focused on a novel method for capturing the peaks and valleys of strain behavior, while preserving the ability to capture steady state strains, at power levels orders of magnitude lower than has previously been reported. Experimental results using representative sine waves as an input signal provided average power levels of 153 microwatts. These extremely low power consumption levels enable the use of conformal strain harvesting patches, and miniaturized vibration harvesters as energy sources.