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Thermoelectric Composite materials show promise, further
improvements under way Next steps focus on device
prototyping
Piezoelectric Low-frequency resonance attained (~31Hz) Voltage
output achieved from HVAC duct (22 mVrms) Integration of harvester
& capacitor under way
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Vibrations in buildings are low acceleration, low frequency
acceleration (gs) frequency (hz)Washing machine 0.31 85Clothes
dryer 0.36 121Small microwave oven 0.23 121External windows by
street 0.07 100HVAC Etcheverry roof 0.25 185HVAC duct Etcheverry
5th floor 0.34 29Refrigerator 0.02 59
Acceleration and frequency of several vibration sou rces in
buildings
S. Roundy, PhD Thesis UC Berkeley 2003. Romy Fain, UC Berkeley
undergraduate.
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V+
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d31 mode S. Roundy, PhD Thesis UC Berkeley 2003
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800
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Si
(not to scale)
Electrode ~200 nmPZT ~ 800 nmElectrode ~160 nmSiO2 ~ 1400 nmSi
~250 1200 nm
PZT
SiO2
( ) ( ){ } [ ] { } [ ] { }
3 31
1
13
n
ij ij k kkk
o
D Q z z
M B De k
-=
= -
= +
Neutral Axis
Neutral Axis
-
No Si film underneath beam
~0.1 0.25
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3
3n
k EIm mL
w = =
Beam length vs resonance frequency
Beam length, mm
Res
onan
ce fr
eque
ncy,
Hz
3.2 e -15 m3 Au mass
5.25 e -10 m3 Si mass
-
03Model predicts 31 Hz if Si film t = 0.25 microns, higher freq
if Si film is thicker.
Function Generator -scan frequencies
Oscilloscope -beam voltage output
Signal amplifier
shaker
Beam
-
Voltage output from energy harvester on duct ~22 mVrms
-
4""
1.3 cm
Dispenser-printed capacitor sandwiched between
current-collectors
Dispenser-printed proof mass
This is the first phase of work to integrate energy harvester
with energy storage
Beam structure
Electrode leadsElectrode bond pads
-
-!0 Thermoelectric
Composite materials show promise, further improvements under
way
Next steps focus on device prototyping
Piezoelectric Low-frequency resonance attained (~31Hz) Voltage
output achieved from HVAC duct (22 mVrms) Integration of harvester
& capacitor under way
-
-567
*4 3 316
316
