title: Cellulose Nanofibril Film as a Piezoelectric Sensor Material.
abstract: Self-standing films (45 μm thick) of native cellulose nanofibrils (CNFs) were synthesized and characterized for their piezoelectric response. The surface and the microstructure of the films were evaluated with image-based analysis and scanning electron microscopy (SEM). The measured dielectric properties of the films at 1 kHz and 9.97 GHz indicated a relative permittivity of 3.47 and 3.38 and loss tangent tan δ of 0.011 and 0.071, respectively. The films were used as functional sensing layers in piezoelectric sensors with corresponding sensitivities of 4.7-6.4 pC/N in ambient conditions. This piezoelectric response is expected to increase remarkably upon film polarization resulting from the alignment of the cellulose crystalline regions in the film. The CNF sensor characteristics were compared with those of polyvinylidene fluoride (PVDF) as reference piezoelectric polymer. Overall, the results suggest that CNF is a suitable precursor material for disposable piezoelectric sensors, actuators, or energy generators with potential applications in the fields of electronics, sensors, and biomedical diagnostics.
authors.affiliation: Department of Automation Science and Engineering, Tampere University of Technology , P.O. Box 692, FI-33101 Tampere, Finland.
authors.forename: Satu
authors.initials: S
authors.lastname: Rajala
authors.affiliation: Microelectronics Research Unit, Faculty of Information Technology and Electrical Engineering, University of Oulu , P.O. Box 4500, FI-90014 Oulu, Finland.
authors.forename: Tuomo
authors.initials: T
authors.lastname: Siponkoski
authors.affiliation: Department of Materials Science, Tampere University of Technology , P.O. Box 589, FI-33101 Tampere, Finland.
authors.forename: Essi
authors.initials: E
authors.lastname: Sarlin
authors.affiliation: Department of Automation Science and Engineering, Tampere University of Technology , P.O. Box 692, FI-33101 Tampere, Finland.
authors.forename: Marja
authors.initials: M
authors.lastname: Mettänen
authors.affiliation: Department of Forest Products Technology, School of Chemical Technology, Aalto University , P.O. Box 16300, FI-00076 Aalto, Espoo, Finland.
authors.forename: Maija
authors.initials: M
authors.lastname: Vuoriluoto
authors.affiliation: Department of Automation Science and Engineering, Tampere University of Technology , P.O. Box 692, FI-33101 Tampere, Finland.
authors.forename: Arno
authors.initials: A
authors.lastname: Pammo
authors.affiliation: Microelectronics Research Unit, Faculty of Information Technology and Electrical Engineering, University of Oulu , P.O. Box 4500, FI-90014 Oulu, Finland.
authors.forename: Jari
authors.initials: J
authors.lastname: Juuti
authors.affiliation: Department of Forest Products Technology, School of Chemical Technology, Aalto University , P.O. Box 16300, FI-00076 Aalto, Espoo, Finland.
authors.forename: Orlando J
authors.initials: OJ
authors.lastname: Rojas
authors.affiliation: Department of Materials Science and Engineering, School of Chemical Technology, Aalto University , P.O. Box 11000, FI-00076 Aalto, Espoo, Finland.
authors.forename: Sami
authors.initials: S
authors.lastname: Franssila
authors.affiliation: Department of Automation Science and Engineering, Tampere University of Technology , P.O. Box 692, FI-33101 Tampere, Finland.
authors.forename: Sampo
authors.initials: S
authors.lastname: Tuukkanen
mesh_terms: D002482:Cellulose / Q000737:chemistry*; D002623:Chemistry Techniques, Analytical / Q000295:instrumentation* / Q000379:methods*; D055590:Electromagnetic Phenomena; D057139:Nanofibers / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D013499:Surface Properties
chemical_list: D011108:Polymers; D002482:Cellulose
keywords: cellulose nanofibrils; image-based analysis; nanocellulose films; piezoelectric sensor materials; relative permittivity; sensitivity measurement