Measurement of the Elastic Modulus of Single Bacterial Cellulose Fibers Using Atomic Force Microscopy

Abstract

The ability of the atomic force microscope to measure forces with subnanonewton sensitivity at nanometer-scale lateral resolutions has led to its use in the mechanical characterization of nanomaterials. Recent studies have shown that the atomic force microscope can be used to measure the elastic moduli of suspended fibers by performing a nanoscale three-point bending test, in which the center of the fiber is deflected by a known force. We extend this technique by modeling the deflection measured at several points along a suspended fiber, allowing us to obtain more accurate data, as well as to justify the mechanical model used. As a demonstration, we have measured a value of 78 +/- 17 GPa for Young's modulus of bacterial cellulose fibers with diameters ranging from 35 to 90 nm. This value is considerably higher than previous estimates, obtained by less direct means, of the mechanical strength of individual cellulose fibers.

The effect of carbon nanotube aspect ratio and loading on the elastic modulus of electrospun poly(vinyl alcohol)-carbon nanotube hybrid fibers

“…Mechanical testing was performed in the AFM force-volume mode [31]. The force spectra were acquired for positions in an array of 64 · 64 pixels spanning square regions of 4.0-6.5 lm width.…”

“…The acquired data were extracted from the force-volume images and analyzed using the Igor Pro software package (Wavemetrics) with a custom analysis routine. The clamped beam model was used for determining the Young's modulus of the fiber [31]. 26 PVA-LSA-CNT, 22 PVA-LSA and 25 PVA fibers with suspended lengths between 3.5 and 6.5 lm were chosen on three separated TEM grids for AFM nanomechanical testing.…”

“…Dissolved in water and ethanol, it can be used in electrospinning [30]. The elastic modulus of individual fibers is measured using atomic force microscopy (AFM) multi-points bending test [31]. Transmission electron microscopy (TEM) is used to measure the loading and the aspect ratio of CNTs in each individual hybrid fiber.…”

Time-dependent rheological behaviour of bacterial cellulose hydrogel

“…Such a fibrous scaffold with high porosity (~99 vol%) is capable to hold a large amount of interstitial water, forming the hydrogel. The growing interest to BC is not only thanks to its excellent biological properties but also because of attractive mechanical properties of BC nanofibres (Guhados et al, 2005). BC fibre-reinforced bio-composites with optimized mechanical properties have found various applications for artificial tissues, such as a BC/fibrin composite for artificial bloody vessel (Brown et al, 2012).…”

Effect of microstructure on anomalous strain-rate-dependent behaviour of bacterial cellulose hydrogel

“…BC nanofibre with stiffness of dozens of GPa [12,13] higher than that of collagen fibres and matrix can provide mechanical reinforcement acting as the main load-bearing component [14]. Since it is non-biodegradable in-vivo, mechanical properties of the BC hydrogel will remain consistent with those of native tissues [8] , enhancing the importance of comprehensive understanding of mechanical behaviour of BC under relevant conditions that is not fully investigated.…”