Compact Energy Conversion Module

This STTR project delivers a compact vibration-based Energy Conversion Module (ECM) that powers sensors for purposes like structural health monitoring (SHM). NASA customers include the ISS and the Orion deep space vehicle, both of which need wireless sensors to monitor and assess structural health. The ECM represents a significant advancement in the use of wireless and self-powered devices by enabling the miniaturization of vibration-based energy harvesting devices suitable for powering sensors. Implications of the innovation There exist two basic problems in reducing the size of vibration-based harvesters that plague all current commercially available devices—both are addressed here. The first is addressed by eliminating the problem of frequency matching in compact devices. The second is addressed by providing a broadband device capable of energy conversion across a range of frequencies. Technical objectives Our initial prototype is a TRL 4 unit that we used to demonstrate our ability to convert kinetic energy to useful electrical power. This prototype combines piezoelectric beam type transducers with artificially induced magnetic fields to force a nonlinear broadband behavior. Phase I shows feasibility through experimental tests and theoretical models that will establish that we can use this approach for compact sizing of low center frequency transducers. Research description Phase I transforms our prototype into a compact system and performs a variety of engineering feasibility tests under both typical ambient kinetic environments and the more high intensity environments that might be found in propulsion testing and launch facilities. Anticipated results Anticipated results include a reduction in the amount of battery waste generated by self-powered electronic devices that enables long-term wireless deployment. Phase I completes a TRL 5 prototype and validates system performance in relevant vibration environments. Phase II delivers a TRL 7 unit.

Energy consumption is now often the most significant problem discussed whenever technology is considered. As the energy efficiency of computational devices drops, self-power via harvested energy becomes increasingly viable for a host of electronic devices for sensing and other applications. The ECM kinetic energy harvester provides self-power for a variety of wireless sensors that include those for in situ structural health monitoring (SHM) of NASA vehicles and infrastructure. ECM directly supports non-destructive evaluation (NDE) systems for safety assurance of future vehicles—especially those making heavy use of composite materials. There is a major effort within NASA, the FAA, and the military to develop integrated vehicle health management (IVHM) technology that uses SHM information for computer controlled recovery actions aimed at avoiding catastrophe. ECM provides enabling technology for this effort. ECM supports the NASA Engineering and Safety Center with tools for independent testing, analysis, and assessment of high-risk projects. NASA applications include self-health monitoring of future exploration vehicles and support structures like habitats and Composite Overwrapped Pressure Vessels (COPVs). ECM-powered sensors reduce maintenance, minimize crew interaction, and reduce spaceflight technical risks and needs. ECM is directly responsive to Topic T3.01, which calls for innovative and compact systems to harvest and convert kinetic energy sources.

The current dependence on batteries to power pacemakers, defibrillators, cochlear implants, neurostimulators, and other medical devices raise numerous safety and reliability concerns. Energy harvesting promises to eliminate the need for bulky batteries and the risk of battery-related defects. Besides medical applications, commercial applications for wireless sensors include Homeland Security structural analysis to mitigate threats (preparedness) and assess damage (response), smart structures, and SHM of civil infrastructures, land/marine structures, and military structures. This broader impact includes practical and widespread monitoring with the potential for preventing catastrophic failures and saving lives. Civil infrastructure includes bridges, highway systems, buildings, power plants, underground structures, and wind energy turbines (alternative and renewable energy). Land/marine structures include automobiles, trains, submarines, ships, and offshore structures. Military structures include helicopters, aircraft, unmanned aerial vehicles (UAV) and others. The need for self-powered SHM sensors is driven by an aging infrastructure, malicious humans, and the introduction of advanced materials and structures. SHM applications are also driven by a desire to lower costs by moving from schedule-based to condition-based maintenance. Key commercial players include Energy Harvesting Sensors and Smart Materials. However, their harvesting products are neither compact nor broadband.