Novel method for mechanical characterization of polymeric nanofibers

Abstract

A novel method to perform nanoscale mechanical characterization of highly deformable nanofibers has been developed. A microelectromechanical system ͑MEMS͒ test platform with an on-chip leaf-spring load cell that was tuned with the aid of a focused ion beam was built for fiber gripping and force measurement and it was actuated with an external piezoelectric transducer. Submicron scale tensile tests were performed in ambient conditions under an optical microscope. Engineering stresses and strains were obtained directly from images of the MEMS platform, by extracting the relative rigid body displacements of the device components by digital image correlation. The accuracy in determining displacements by this optical method was shown to be better than 50 nm. In the application of this method, the mechanical behavior of electrospun polyacrylonitrite nanofibers with diameters ranging from 300 to 600 nm was investigated. The stress-strain curves demonstrated an apparent elastic-perfectly plastic behavior with elastic modulus of 7.6± 1.5 GPa and large irreversible strains that exceeded 220%. The large fiber stretch ratios were the result of a cascade of periodic necks that formed during cold drawing of the nanofibers.

A MEMS nano-extensometer with integrated de-amplification mechanism

“…However, mounting of different types of a specimens is possible. Several approaches for mounting of specimens were presented in the literature (Franklin et al 2002;Jungen et al 2007a, b;Jonnalogadda et al 2010;Karp et al 2009;Kawano et al 2006;Naraghi et al 2007;Ozkan et al 2010;Stampfer et al 2006).…”

A Multi-step Method for In Situ Mechanical Characterization of 1-D Nanostructures Using a Novel Micromechanical Device

“…Also falling under the same category are the polysilicon MEMS structures fabricated by Boyce et al [6] in order to study strength distributions in freestanding polysilicon layers. Another example of this type of devices is a MEMS test bed using external AFM piezoelectric actuation and optical digital image correlation method for displacements measurements [7]. On the other hand, Zhu et al [8] designed an on-chip nanoscale tensile testing platform for testing 1D nanostructures and thin films that consisted of a thermal/ electrostatic actuator for load application and a differential capacitance load sensor for displacement and load measurement.…”

A Uni-Axial Nano-Displacement Micro-Tensile Test of Individual Constituents from Bulk Material

“…[38], the global displacement measurement is performed by extracting relative rigid body displacements of specimen regions by digital image correlation, see Fig. 8, although here a dedicated global digital image correlation (GDIC) algorithm [35,37] has been employed for improved accuracy.…”