1. nanocellulose for piezoelectric materials
Konrad Klockars

2. Piezoelectricity – An electromechanical effect
Piezoelectric effect: mechanical stress induces change in polarization density
Also converse effect: Applied electrical field induce mechanical strain
Observed in many natural materials, e.g. cellulose crystals
ZnO crystals conventionally used as piezoelectric material
Converse effect: 𝐷=𝑑∗σ
Simplified formula!
Displacement from induced polarization
Applied stress, caused by electric field
Transverse Piezoelectric constants
Bass P. S. et al Electroact. Pol. Actuators and Devices (EAPAD)

3. Piezoelectricity in cellulose
Polarizability/crystallinity of cellulose
Only shear constants present in cellulose
Monoclinic/triclinic crystal unit in cellulose
Alignment of cellulose chains important
Kim J.-H. et al Journ. of Bionic Eng.
Csoka L. et al ACS Macro Letters

4. Nanocrystalline cellulose films
Assembly using deposition plate and electric field
Withdrawal rate and solvent evaporation
Field strength and frequency
Converse piezoelectric effect with AFM
Hoeger I et al Soft Matter
Csoka L. et al ACS Macro Letters

5. Electro-active paper
20-30 µm thick films with LiCl/DMAC, after stretching
Direct piezoelectric effect with picoammeter
Acoustic output from electrical signal generator
Abas Z. et al SPIE proceedings
Zhai L. et al Cellulose
Kim J.-H. et al Journ. of Bionic Eng.

6. Cellulose and… NCC as reinforcement in electroactive polymers
40 % larger rotation actuation(strain) with 1,5 % ncc
ZnO nanorods grown on cellulose substrate film
6 times larger piezoelectric constant
BaTiO3 embedded in cellulose fibres
Bass P. S. et al Electroact. Pol. Actuators and Devices (EAPAD)
Mahadeva S. K. et al IEEE

7. conclusions
The piezoelectric properties of cellulose can be utilized in many applications
Speakers, vibration sensors, sound detectors
Voltage generators, energy harvesters
Microsensors, balances
Self-powering portable electronic devices
Biomedical devices, prosthetics, artificial muscles
Benefits
Lightweight and flexible
Biodegradable and biocompatible
Low cost

8. References
Bass P. S., Baltzell M., Zhang L., Zhang D., Tu M. & Cheng Z. Electromechanical response of NCC-PEO composites. Electroactive Polymer Actuators and Devices (EAPAD) San Diego, California, USA SPIE Proceedings. Vol DOI: /
Bernardini F., Fiorentini V. & Vanderbilt D. Spontaneous polarization and piezoelectric constants of III-V nitrides. Physical Review B. 1997, vol 56. DOI:
Csoka L., Hoeger I. C., Rojas O. J., Peszlen I., Pawlak J. J. & Peralta P. N. Piezoelectric Effect of Cellulose Nanocrystals Thin Films. ACS Macro Letters. 2012, vol. 1:7. pp
Zhai L., Mun S., Gao X., Kim J. V. & Kim J. Cellulose electro-active paper fabricated by facile solvent exchange pretreatment and its physical and electromechanical properties. Cellulose DOI: /s y
Abas Z., Kim H. S., Zhai L. & Kim J. Experimental and numerical study of cellulose-based electro-active paper energy harvester. Nanosensors, Biosensors, and Info-Tech Sensors and Systems 2014, 90601G. San Diego, California, USA SPIE Proceedings. Vol DOI: /
Kim J.-H., Yun S., Kim J.-H., Kim J. Fabrication of Piezoelectric Cellulose Paper and Audio Application. Journal of Bionic Engineering. 2009, vol. 6:1. pp DOI: /S (08)
Ko H.-U., Mun S., Min S.-K., Kim G.-W. & Kim J. Fabrication of Cellulose ZnO Hybrid Nanocomposite and Its Strain Sensing Behavior. Materials. 2014, vol 7. pp DOI: /ma
Mahadeva S. K., Walus K. & Stoeber B. Fabrication and testing of piezoelectric hybrid paper for mems applications IEEE 27th International Conference on Micro Electro Mechanical Systems (MEMS). San Francisco, California, USA IEEE. DOI: /MEMSYS
Hoeger I., Rojas O. J., Efimenko K., Velev O. D. & Kelley S. S. Ultrathin film coatings of aligned cellulose nanocrystals from a convective-shear assembly system and their surface mechanical properties. Soft Matter. 2011, vol 7. pp DOI:  /C0SM01113D