University Of Michigan’s Piezoelectric Energy Generator Is World’s Smallest And Most Efficient!

The field of instrumentation requires various sensors placed at different places in a machine collecting and transmitting data at all times. For its working, the transducers require an auxiliary power source. This power source can be a local source such as a battery or can be a remote source which is connected to the transducers through wires. Even though the transmission system of the transducers can be wireless, the power requirement is essentially wired in nature. When the data is to be collected from obscure positions of a machine, several limitations arise for placing the sensors. These primarily include the placement of the battery or routing of the wires without affecting the system components. Hence instrumentation in case of moving systems which are small in size is difficult.

The scientists at University of Michigan have designed what they claim to be world’s smallest and most energy efficient energy harvester. The energy harvester is essentially a piezoelectric crystal based system which derives its energy when it is subjected to stress due to vibrations. Piezoelectric crystals have the property to generate an electrical voltage when there is a change in their dimensions. This change in dimension can be achieved by mechanical stress on the crystal material. The prototype they have designed focuses on the power requirements of the sensors which are to be installed in rotating parts of machines where the vibrations will produce dimension changes in the crystal.

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Following are the features of this compact energy producing integrated system:

[*]Energy producing part of generator is about 27 cubic millimeters in volume.
[*]System consisting of piezo crystal and power modulator circuit is size of penny.
[*]Bandwidth of 14 hertz.
[*]Vibration operating frequency of 155 hertz.
[*]200 microwatts of energy generation possible when the vibrations have amplitude of 1.5g.
[*]Provision of 1.85 volt capacitor which is charged by the generated energy with the help of power modulator circuitry.
[*]Novel silicone micromachining technique used to fabricate harvesters with high quality piezoelectric materials in bulk.

The presentation of the research work is expected in June at the 16th International Conference on Solid-State Sensors, Actuators, and Microsystems (TRANSDUCERS 2011) in Beijing .The device promises to bring down the cost and efforts associated with the installation maintenance, replacement and troubleshooting of the power sources for the sensors. The energy harvesters by the team is claimed to have a shelf life of 10 to 20 years without the need of maintenance or replacement.

"In a tiny amount of space, we've been able to make a device that generates more power for a given input than anything else out there on the market," according to Khalil Najafi. He is one of the system's developers and chair of Electrical and Computer Engineering along with Erkan Aktakka, one of the system's developers and a doctoral student.

The power sources for the transducers will help instrumentation engineers to gather different signals from automobiles. Or they can be used in biomedical applications for powering the medical implants. The applications are numerous and we can look forward for its intriguing applications from the Instrumentation Engineers.

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