nanocellulose based piezoelectric sensors · polyvinylidene fluoride (pvdf) reference sensor shows...
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Tampere University of Technology
Nanocellulose based piezoelectric sensors
CitationTuukkanen, S., Viehrig, M., Rajala, S., & Kallio, P. (2016). Nanocellulose based piezoelectric sensors. 1-2.Paper presented at Advances in Functional Materials (AFM 2016), ICC , Korea, Republic of.
Year2016
Link to publicationTUTCRIS Portal (http://www.tut.fi/tutcris)
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Download date:16.12.2020
Nanocellulose based
piezoelectric sensors
Sampo TuukkanenAssistant Professor (tenure track),
BioMediTech,
Department of Automation Science and Engineering,
Tampere University of Technology (TUT)
Tampere,
FINLAND
Outline
• Nanocellulose fabrication
• Piezoelectricity of wood cellulose
• Nanocellulose film fabrication
• Piezoelectric sensitivity measurements
• Results and conclusions
09.08.2016Sampo Tuukkanen 2
Nanocellulose fabrication
09.08.2016Sampo Tuukkanen 3
[For more details see e.g.: Moon et al., Chemical Society Reviews 40(7) (2007) 3941]
Chemical structure of cellulose:
Cellulose nanocrystal (CNC)
• AFM (atomic force microscope) image
shows that CNCs are highly
crystalline, rigid, rod-like nanoparticles
(nanowhiskers) with a high aspect ratio
1.9.2015Sampo Tuukkanen, TUT, Tampere, Finland 4
[AFM images by S. Tuukkanen, in 2014 at Nanomicroscopy Center, Aalto University, Espoo, Finland]
Diameter
of 5-20 nm
Length of a
few 100 nm
“CNC
nanowhisker”
Piezoelectricity of CNCs
09.08.2016Sampo Tuukkanen 5
000000
00000
00000
25
14
d
d
dmn
[Zuluaga et al. (2013)]
• Piezoelectric effect = Electric charge
separation by applied mechanical force
• The piezoelectric tensor dmn is determined
by the symmetry of a crystal lattice
• The monoclinic C2 symmetry and the
cancellation effects result into
piezoelectric coefficient matrix:
[E. Fukada, J. Phys. Soc. Japan (1955)]
Cellulose crystal
[[C6H10O5]n] unit cell:
Chemical structure of cellulose:
Nanocellulose film fabrication
• Aqueous dispersion of CNF
material (bleached birch cellulose
mass) produced by a mechanical
homogenizing process (6 passes
through a microfibrillator)
• CNF film was prepared by
pressure filtering, followed by
pressing and drying in hot-press
(2 h @ 100 C), resulting a
bendable CNF film containing
amorphous areas and non-
aligned CNC crystals areas
09.08.2016Sampo Tuukkanen 6
[Described in details in: M. Pääkkö et al.
Biomacromolecules 8 (2007) 1934]1 cm
Cellulose
nanocrystals
(CNC)
Amorphous
nanocellulose
[S. Rajala et al, ACS Applied
Materials and Interfaces (2016)]
Permittivity and hysteresis
• Relative permittivity and loss tangent were
similar to typical dielectric polymers
• Polarization-voltage hysteresis curves for
CNF film showed has some level of
ferroelectric properties at high electric fields
09.08.2016Sampo Tuukkanen 7
[S. Rajala et al, ACS Applied Materials and Interfaces (2016)]
CNF sensor assembly
09.08.2016Sampo Tuukkanen 8
PET
Cu
Cu
PET
Nanocellulose film
125 µm
100 nm
100 nm
125 µm
CNF: 45 µm
• For piezoelectric sensitivity measurements, five nominally identical
CNF sensors were assembled
• Pieces of CNF films assembled between two evaporated copper
electrodes on polyethylene terephthalate (PET) substrate using
adhesive film
• Crimp connectors (Nicomatic Crimpflex) were used for getting a
reliable contacts to the copper electrode on flexible PET substrate
[S. Rajala et al, ACS Applied Materials and Interfaces (2016)]
Measurement setup
• Mini-Shaker (Brüel & Kjaer type 4810) used for sensitivity measurements
• Reference sensors for dynamic and static forces (normal direction)
• DUT (device-under-test) placed horizontally on the metal plate
• The sensor sensitivity measure here is closely related to transverse
piezoelectric coefficient d33 (from piezoelectric tensor)
09.08.2016Sampo Tuukkanen 9
[For details see: S. Tuukkanen et al., Synthetic
Metals (2012) or IEEE Sensors (2015)]
Sensitivity measurements
• Static force of ~3 N was used to keep
sample steady
• Excitation with 2 Hz sinusoidal input signal
of 1 V (peak to peak) results in a dynamic
force of ~1.3 N
• Excitation by applying the force in the middle
of the sensor; measurement repeated 3-9
times from both sides, resulting in a total of
6-18 excitations per sensor
• The sensor sensitivity by dividing the
generated charge by the dynamic force
• The unit of sensitivity is pC/N
09.08.2016Sampo Tuukkanen 10
Sensor
sample
Piezoelectric sensitivity
09.08.2016Sampo Tuukkanen 11
• Mean piezoelectric sensitivity
± standard deviation for
excitations from each side of the
CNF-sensors are shown in the
Table 1
• Sensitivity from different
excitation positions for the
CNF sensor and a
polyvinylidene fluoride (PVDF)
reference sensor shows only
small variations
• The average sensitivity for the
CNF sensor was 4.7 pC/N, while
for the reference PVDF sensor
was 27.5 pC/N
[S. Rajala et al, ACS Applied Materials and Interfaces (2016)]
Sensor linearity and hysteresis
• Plots show (a) nonlinearity and (b)
hysteresis curves for the CNF and
the PVDF reference sensor
• Nonlinearity (charge vs. force
curve by fitting a first degree
polynomial via least-squares
minimization) was found to be
(0.86 ± 0.48) pC for CNF and
(6.47 ± 3.76) pC for PVDF
• Sensor hysteresis (with
increasing vs. descreasing force)
was below 1 pC in maximum for
both sensors
09.08.2016Sampo Tuukkanen 12
[S. Rajala et al, ACS Applied Materials and Interfaces (2016)]
Nonlinearity
Sensor hysteresis
Conclusions and summary
09.08.2016Sampo Tuukkanen 13
• Prepared self-standing 45-μm-thick cellulose nanofibrils (CNF) showed piezoelectric
sensitivity of 4.7 ± 0.9 pC/N
Not (intentionally) oriented/polarized, organization by fabrication process possible
Sensitivity values align between quartz (2.3 pC/N) or PVDF (-30 pC/N)
• Nanocellulose is a promising solution-processable, renewable and disposable
piezoelectric material!!
• Ongoing work: Orientation/polarization & Flexibility by mixing with elastomer
[S. Rajala et al, ACS
Applied Materials and
Interfaces (2016)]
Acknowledgements
09.08.2016Sampo Tuukkanen 14
Nanocellulose and film preparation:
Aalto University, Department of Forest Products Technology &
Department of Materials Science and Engineering, Finland
• Maija Vuoriluoto, Dr. student: CNF-film preparation
• Orlando Rojas, Prof: Supervision
• Sami Franssila, Prof: Supervision
Permittivity and hysteresis measurements:
University of Oulu, Microelectronics Research Unit, Finland
• Tuomo Siponkoski, Dr. student: Hysteresis and permittivity
• Jari Juuti, D.Sc. (Tech.), Adj. Prof: Supervision
Film characterisation and sensitivity measurements:
Tampere University of Technology (TUT), Department of
Automation Science and Engineering, Finland
• Satu Rajala, D.Sc. (Tech.): Sensitivity measurements
• Essi Sarlin, D.Sc. (Tech.): SEM imaging
• Marja Mettänen, D.Sc. (Tech.): Image based analysis
• Arno Pammo, B.Sc. (Tech.): Sensor assembly
• Sampo Tuukkanen, Ph.D., Asst. Prof: Supervision
Funding from: