Thin-film diaphragms of cellulose nanofiber fabricated using high-concentration polar dispersion for application to MEMS actuators

Publication date: Available online 22 February 2019Source: Sensors and Actuators A: PhysicalAuthor(s): Satomitsu ImaiAbstractA method of fabricating thin-film diaphragms of cellulose nanofiber (CNF) for the application of displacement membranes of MEMS actuators or microfluidic devices was developed and the mechanical characteristics were evaluated. CNF has high strength and elastic modulus; however, it is necessary to provide flexibility for the use as a displacement membrane. A polar solvent, tertiary-butyl alcohol (tBA), at a high concentration of approximately 66 vol%, was used to thin the CNF film, that is, to reduce the aggregation and viscosity of the CNF. The CNF films fabricated by this method were of approximately 4-μm thickness. The fabricated films had a good gas barrier property and had an isotropic Young's modulus. An evaporation layer of aluminum (approximately t0.3 μm) was deposited on the surface of the CNF film as a shield layer for water repellency. The displacement characteristics of the diaphragm of the film (t4 μm) were measured in the actuators using air pressure or a magnetic field and they were close to those of a polyimide thin film of thickness 7.5 μm. The dynamic reproducibility and resilience of the displacement were ensured. The proposed method could easily form CNF films of thickness down to several micrometers and the fabricated films could be used as displacement membranes for gases and liquids.
Source: Sensors and Actuators A: Physical - Category: Physics Source Type: research