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.
MCB Clean Room Solutions, LLC The objective of this NSF Phase I SBIR project was to develop a Micro-Vibrational Energy Harvester using a novel MEMS (MicroElectroMechanical System) design. MEMS are tiny machines fabricated on Silicon wafers using semiconductor processes. The Micro-Vibrational Energy Harvester converts environmental vibrations, for example from an air conditioning system, into electricity. The focus of the project was to develop a design that would more efficiently convert vibrations into electricity to power a wireless sensor. During the project we mathematically modeled the device to create a design to produce sufficient power to operate a wireless sensor. Next the semiconductor manufacturing process steps were developed and integrated into a flow to fabricate the test devices. Several test chips were fabricated and packaged, demonstrating the feasibility of the design and manufacturing approach. During the project manufacturing process reliability risks were identified that will be addressed in Phase II. A testing capability was also developed in the Phase I project for testing additional devices. Wireless sensor networks (WSNs) are 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. However, growth of these applications has been limited by sensor costs and the need for battery changes. It is 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 a Micro-Vibrational Energy Harvester with sufficient power to replace or recharge batteries would enable the growth of these applications and the wireless sensor market, leading to cost and energy savings.
