Cellulose Nanofibril Film as a Piezoelectric Sensor MaterialNanocelluloses, including cellulosic nanoﬁbrils and nanocrystals, are interesting renewable biobased nanomaterials with potential applications in different ﬁelds.
The nanoscale dimensions and strong ability to form entangled porous networks make nanocelluloses suitable materials for fabrication of lightweight membranes, ﬁlms, and nanopapers, all of which can be processed in aqueous media. Processing in aqueous media ensures low cost and high throughput manufacturing of functional devices for electronics, sensing, and optics.
The piezoelectricity of wood, i.e., the change of electrical polarization in a material in response to mechanical stress, has been known for decades. The piezoelectric effect is highly enhanced if one considers the isolated crystalline building blocks of wood, namely, cellulose nanocrystals (CNC). However, related issues have been covered in the scientiﬁc literature to a very limited extent and only few recent reports discuss experimental evidence of CNC piezoelectricity.
Figure: Schematic representation of nanocelluloses obtained from wood cellulose fibers. The cellulose fibers are first deconstructed into microfibrils and after various processing steps into cellulose nanofibrils (CNF). Cellulose nanocrystals (CNC) can be further obtained by using acid hydrolysis.
A paper "Cellulose Nanoﬁbril Film as a Piezoelectric Sensor Material, by Satu Rajala, Tuomo Siponkoski, Essi Sarlin, Marja Mettänen, Maija Vuoriluoto, Arno Pammo, Jari Juuti, Orlando J. Rojas, Sami Franssila, and Sampo Tuukkanen, in ACS Applied Materials & Interfaces 8(24) (2016) 15607" presents a thorough study of the piezoelectric properties of prepared cellulose nanofibril (CNF) films. The piezoelectric properties of nanocellulose is rarely reported in the literature, making this collaboration work between TUT, Aalto University and University of Oulu quite significant on the field.