| Abstract |
Acoustic pressure or mechanical force sensing via piezoelectric
coupling is closely related to the harvesting of electrical energy
from acoustical and mechanical energy sources. In this talk,
mesoscale and microscale piezoelectric transducers for acoustic and
vibrational sensing and energy harvesting will be discussed. For
example, a micromachined piezoelectric microphone has been
developed for aeroacoustic applications with a demonstrated
sensitivity of 0.75 µV/Pa, a dynamic range greater than six orders
of magnitude (47.8 –169 dB, ref . 20 µ Pa), and a resonant
frequency of 50.8 kHz. In addition, acoustic energy harvesting has
been demonstrated using a mesoscale (~ 2 cm) Helmholtz resonator
machined in aluminum, delivering 25 mW to a resistive load at a
sound pressure level (SPL) of 152 dB (ref. 20 µPa. This acoustic
energy may be used to locally power a wireless active liner for
suppression of engine noise in turbofan engines, where acoustic
levels typically reach up to 150 dB. For space-constrained
applications, a micromachined acoustic energy harvester was also
recently developed. It employed a silicon-micromachined, circular,
piezoelectric composite diaphragm. Experimental results indicated
a maximum output power density of 0.34 µW/cm2 at 149 dB (ref. 20
µPa) and a potential output power density of 250 µW/cm2 with an
improved fabrication process. Similar examples will be given for
cantilever-based vibrational energy harvesters. Finally, some
system considerations will be discussed for energy harvesting-
powered systems. As the volume of the energy harvester is reduced,
as expected, the harvestable power decreases given a specific power
density for the available ambient conditions and material
parameters. For system designs, the power balance between average
power dissipation and average power harvesting determines the
maximum duty cycle possible under specific energy harvesting
conditions. |
| Bio |
Toshikazu (Toshi) Nishida is currently an associate professor in
the Department of Electrical and Computer Engineering (ECE) and an
Affiliate Associate Professor in the Department of Mechanical and
Aerospace Engineering (MAE) at the University of Florida,
Gainesville, Florida. He is a founding member of the
Interdisciplinary Microsystems Group at the University of Florida.
His research interests include solid-state physical sensors and
actuators, transducer noise, strained semiconductor devices, and
reliability physics of semiconductor devices. He and his students
are currently investigating strain effects in piezoresistive
microelectromechanical systems (MEMS) transducers and advanced CMOS
devices, noise mechanisms in piezoresistive MEMS transducers, MEMS
piezoelectric transducers for vibrational energy reclamation, MEMS
capacitive microphones, and biomedical applications of MEMS.
He received his Ph.D. (1988) and M.S. degrees in Electrical and
Computer engineering and B.S. degree in Engineering physics at the
University of Illinois at Urbana-Champaign. With colleagues and
students, he has received three best paper awards. He also received
the 2003 College of Engineering Teacher of the Year award. He holds
four U.S. patents. |
| Cite this work |
Researchers should cite this work as follows:
|
| Time |
11:00 AM, March 19, 2007 |
| Location |
Birck Nanotechnology Center, Room 2001 |
| Tags |
- devices
- energy conversion
- nano electro-mechanical systems
- nanoelectronics
- research seminar
- sensors
|