Methods and systems for sensing activity using energy harvesting devices

A method for monitoring activities related to one or more items within an aircraft, said method comprising:

• configuring the items such that at least one activity associated with the item is operable to power a sensor using a thermoelectric energy harvesting device exposed to a thermal gradient across an insulation blanket of the aircraft;
• transmitting a unique identification code on a periodic basis, whether or not a state of the sensor changes, as a verification that the sensor and the energy harvesting device are operable, the unique identification code indicating whether or not a triggering event has occurred;
• and
• correlating the unique identification code with a physical location within an aircraft for purposes of physical inspection.

A system for monitoring activities relating to movable and removable items within a structure, said system comprising:

• an electrical energy storage device;
• an energy harvesting device operable to store harvested energy in said electrical energy storage device, the energy harvesting device comprising a thermoelectric generator exposed to a thermal gradient across at least one of a hydraulic line and an insulation blanket;
• a sensor element configured to output signals corresponding to one or more of removal, installation, and a shift in position of a corresponding item within the structure;
• and
• a transmitter configured to receive the signals from said sensor element, said transmitter further configured to transmit unique identification information and data corresponding to the signals received from said sensor element, the unique identification information corresponding with a location of the item on the structure, said sensor element and said transmitter configured to use energy from one or both of said energy harvesting device and said electrical energy storage device, said transmitter further configured to periodically transmit the unique identification information on a periodic basis, whether or not a state of said sensor element changes, as a verification that said system is operable.