A Thick-film Piezoelectric Multimorph Cantilever.
A Thick-Film Piezoelectric Multimorph Cantilever
Kok, S. L., White, N. M. and Harris, N. R
School of Electronics and Computer Science, University of Southampton,
Southampton SO17 1BJ, UK
Corresponding author email: slk05r@ecs.soton.ac.uk
Abstract:
Free-standing thick-film cantilevers have the potential to be used as micro-generators
as well as self-generating resonant sensors. Earlier versions of free-standing devices
[2] were implemented by fabricating in the form of multilayer structures. Instead of
structures with a plate of PZT sandwiched between upper and lower electrodes,
multimorph structures consist of three individual PZT plates having equal thicknesses
(of about 40 μm each). Ag/Pd conductors form the separators between the layers, also
acting as electrodes on the upper and lower layers of the structure. Each piezoelectric
plate was polarised in its thickness direction with two different modes: parallel and
series. In the parallel mode, both the upper and lower PZT plates were polarised in the
opposite direction, while in the series mode the upper plates and the lower plates were
polarised in the same direction. The centre plate of PZT acts as the neutral axis of the
structure. Using the direct piezoelectric effect, a voltage was generated when the
multimorph structures were bent by the application of a harmonic excitation. An
output power of 10 μW was measured for the parallel polarised sample. Series
multimorphs, however, exhibited a non-linear effect, where the output power was 21
μW for an up-sweeping frequency, but was reduced by a factor of 50 for a downsweeping frequency.
25
1.0E+02
1.0E+00
1.0E-01
Parallel
1.0E-02
Individual PZT
1.0E-03
Series
Output Power (uW)
Output Power (uW)
1.0E+01
20
Up-sweeping
15
Down-sweeping
10
5
1.0E-04
1.0E-05
210
220
230
240
250
Frequency (Hz)
260
270
280
0
250
260
270
280
290
300
310
Frequency (Hz)
Fig 1. Measured electrical output power from a) parallel polarised samples and b)
serial polarised samples.
References
[1] Ha, S.K. and Kim, Y.H. (2002) Analysis of A Piezoelectric Multimorph in Extensional and Flexural
Motions. Journal of Sound and Vibration. 253 (5). pp. 1001-1014.
[2] Kok, S. L., White, N. M. and Harris, N. R. (2008) Free-standing thick-film piezoelectric device.
Electronics Letters, 44 (4). pp. 280-281.
Kok, S. L., White, N. M. and Harris, N. R
School of Electronics and Computer Science, University of Southampton,
Southampton SO17 1BJ, UK
Corresponding author email: slk05r@ecs.soton.ac.uk
Abstract:
Free-standing thick-film cantilevers have the potential to be used as micro-generators
as well as self-generating resonant sensors. Earlier versions of free-standing devices
[2] were implemented by fabricating in the form of multilayer structures. Instead of
structures with a plate of PZT sandwiched between upper and lower electrodes,
multimorph structures consist of three individual PZT plates having equal thicknesses
(of about 40 μm each). Ag/Pd conductors form the separators between the layers, also
acting as electrodes on the upper and lower layers of the structure. Each piezoelectric
plate was polarised in its thickness direction with two different modes: parallel and
series. In the parallel mode, both the upper and lower PZT plates were polarised in the
opposite direction, while in the series mode the upper plates and the lower plates were
polarised in the same direction. The centre plate of PZT acts as the neutral axis of the
structure. Using the direct piezoelectric effect, a voltage was generated when the
multimorph structures were bent by the application of a harmonic excitation. An
output power of 10 μW was measured for the parallel polarised sample. Series
multimorphs, however, exhibited a non-linear effect, where the output power was 21
μW for an up-sweeping frequency, but was reduced by a factor of 50 for a downsweeping frequency.
25
1.0E+02
1.0E+00
1.0E-01
Parallel
1.0E-02
Individual PZT
1.0E-03
Series
Output Power (uW)
Output Power (uW)
1.0E+01
20
Up-sweeping
15
Down-sweeping
10
5
1.0E-04
1.0E-05
210
220
230
240
250
Frequency (Hz)
260
270
280
0
250
260
270
280
290
300
310
Frequency (Hz)
Fig 1. Measured electrical output power from a) parallel polarised samples and b)
serial polarised samples.
References
[1] Ha, S.K. and Kim, Y.H. (2002) Analysis of A Piezoelectric Multimorph in Extensional and Flexural
Motions. Journal of Sound and Vibration. 253 (5). pp. 1001-1014.
[2] Kok, S. L., White, N. M. and Harris, N. R. (2008) Free-standing thick-film piezoelectric device.
Electronics Letters, 44 (4). pp. 280-281.