nanocellulose for piezoelectric materials Konrad Klockars 26.2.2015

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. 2014. Electroact. Pol. Actuators and Devices (EAPAD)

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. 2009. Journ. of Bionic Eng. Csoka L. et al. 2012. ACS Macro Letters

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. 2011. Soft Matter Csoka L. et al. 2012. ACS Macro Letters

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. 2014. SPIE proceedings Zhai L. et al. 2015. Cellulose Kim J.-H. et al. 2009. Journ. of Bionic Eng.

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. 2014. Electroact. Pol. Actuators and Devices (EAPAD) Mahadeva S. K. et al. 2014. IEEE

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

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) 2014. San Diego, California, USA. 9.3.2014. SPIE Proceedings. Vol. 9056. DOI:10.1117/12.2044418 Bernardini F., Fiorentini V. & Vanderbilt D. Spontaneous polarization and piezoelectric constants of III-V nitrides. Physical Review B. 1997, vol 56. DOI: http://dx.doi.org/10.1103/PhysRevB.56.R10024 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. 867-870 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. 2015. DOI: 10.1007/s10570-015-0553-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. 9.3.2014. SPIE Proceedings. Vol. 9060. DOI: 10.1117/12.2044639 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. 18- 21. DOI:10.1016/S1672-6529(08)60096-7 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. 7000-7009. DOI:10.3390/ma7107000 Mahadeva S. K., Walus K. & Stoeber B. Fabrication and testing of piezoelectric hybrid paper for mems applications. 2014 IEEE 27th International Conference on Micro Electro Mechanical Systems (MEMS). San Francisco, California, USA. 26-30.1.2014. IEEE. DOI: 10.1109/MEMSYS.2014.6765717 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. 1957-1967. DOI: 10.1039/C0SM01113D