Description: Monitoring of structural strain is a well-established method for assessing the fatigue life and operational loads of aerospace vessels, aircraft, bridges, and other load-bearing structures. Information from extensive instrumentation using 100's to 1000's of strain gages can be fed into a condition based maintenance (CBM) algorithm to improve structural health assessments, detect damage, and lower maintenance costs. Current methods for measuring strain are too cumbersome, bulky, and costly to be practical for a large scale dense network of strain sensors. Furthermore, existing piezoelectric-based vibrational energy harvesters are built around general purpose components designed for operation in low-temperature application spaces. To realize pervasive structural health monitoring across a wide range of thermal and vibrational environments, a low cost, minimally intrusive, low maintenance, and reliable technology is needed. Cutting edge microelectromechanical systems (MEMS) sensors for measurements of strain, acceleration, pressure, acoustic emission, and temperature are becoming increasingly available for use in CBM and structural health monitoring (SHM). While these sensors offer a promising future for wireless sensing networks (WSN), implementation for CBM remains cumbersome due to the lack of versatile, cost-effective powering solutions. Wiring external power to sensors is an unattractive solution given the required installation overhead and associated maintenance costs. Battery powered solutions are unreliable and battery maintenance for a dense network of thousands of sensor nodes is not practical. For this STTR effort, Prime Photonics proposes to team with Virginia Tech to develop a multimode vibrational-thermal harvester with effective energy capture and efficient conversion.

Benefits: The initial NASA commercial application of the Energy Harvesting Wireless Strain Sensor (EHWSS) technology would be in support of advanced flight testing of low subsonic and high supersonic aircraft. The EHWSS system would facilitate monitoring of strain levels in key components of aircraft, particularly in areas that might prove problematic for traditional, wired sensing technologies. Refinement of power budgets and operation environments would allow for extension of EHWSS systems into NASA manned or unmanned space missions for spacecraft structural monitoring, including strain monitoring and/or damage event detection.

Prime Photonics will market the Energy Harvesting Wireless Strain Sensor (EHWSS) technology for use in support of US military mobile platforms (e.g. ships, aircraft), as well as commercial ships and other private sector industrial and structural monitoring applications such as infrastructure health monitoring (e.g. buildings and bridges) industrial equipment monitoring (e.g. mills and HVAC systems) and power generation equipment (e.g. wind turbines, steam turbines).