MEMS platform for on-chip nanomechanical experiments with strong and highly ductile nanofibers

A new nanoscale tension testing platform with on-chip actuation and the unique capability for nanoscale mechanical characterization of highly deformable and strong nanostructures is presented. The specimen force and extension measurements are based on optical imaging, supported by digital image correlation, which allows the resolution of 20 nm specimen extensions and force measurements better than 30 nN, without the use of high-resolution electron microscopy. The breakthrough of this nanomechanical testing platform is the ability to study the mechanical behavior of nanostructures subjected to a wide range of forces (30 nN-300 mu N) and displacements (20 nm-100 mu m), which are significantly beyond the limits of typical surface micromachined MEMS with on-chip actuators, such as comb-drives and thermal actuators. The utility of this device in experimental nanomechanics is demonstrated by investigating the mechanical behavior of electrospun polyacrylonitrile nanofibers with diameters of 200-700 nm subjected to strains as high as 200%. The mechanical property measurements were compared to and agreed well with off-chip measurements by an independent testing method, which validates the capability of this on-chip testing platform to characterize strong and highly ductile nanomaterials.