SBIR Phase I: MEMS Micro-Energy Harvester for Integrated Self-Powered Wireless Sensors

This Small Business Innovation Research (SBIR) Phase I project is to develop a self-powered Microelectromechanical Systems (MEMS) piezoelectric wireless sensor platform architecture based on a Micro-Vibrational-Energy-Harvester (uVEH) that can be monolithically integrated with MEMS sensors. Current commercially available vibrational energy harvesters are too large and expensive to integrate with wireless sensors, but small, inexpensive MEMS solutions provide too little power. The Phase I project focuses on prototyping the enabling piezoelectric bimorph MEMS energy harvester technology. Preliminary modeling predicts that the proposed architecture could produce at least two to three orders of magnitude higher power than current single element surface-micromachined MEMS uVEHs. The research objectives for this project include modeling, design, process development, and fabrication of the prototype uVEH, electrical characterization, and hybrid integration of the prototype with charging electronics. The resulting MEMS uVEH prototype can be used to replace or recharge the batteries in existing wireless sensor motes. In subsequent phases the MEMS uVEH will be integrated monolithically with other MEMS sensors to form the sensor core of a miniature self-powered wireless mote. The broader impact/commercial potential of this project is to enable increased usage of Wireless Sensor Networks (WSNs) by eliminating difficult or costly battery replacement. WSNs have been predicted to provide many millions of dollars of savings to industry, government, and consumers by eliminating waste and losses in energy usage, process inefficiencies and problems, and equipment and infrastructure failure and downtime. Embedded sensors can monitor energy usage, air quality, and equipment health as well hazardous conditions such as chemical and biological agents and process chemistries. However, it has been estimated that 90% of envisaged uses of WSNs are impractical because the batteries would be inaccessible or prohibitively expensive to access. In many of these embedded applications solar and thermal gradient energy sources are not available, and ambient vibrations may be the only external source of energy. Development of the proposed volume-microfabricated sensor platform to produce small, inexpensive self-powered sensors would enable WSNs to be used in many applications previously closed to them because of battery maintenance costs, inaccessibility, or the number of sensor nodes required. The new processes, especially piezoelectric material deposition processes, that will be developed will add to the repertoire of materials available by students and other researchers.