Fabrication and Mechanical Characterization of Carbon Nanotube Based Nanoknives

A prototype microtome knife for cutting ~100 nm thick slices of frozen-hydrated biological samples has been constructed by use of multiwalled carbon nanotubes (MWCNT). A piezoelectric-based 3-D manipulator was used inside a scanning electron microscope (SEM) to select and position individual MWCNTs, which were subsequently welded in place by electron beam-induced deposition (EBID). The device employs a pair of tungsten needles with provision to adjust the distance between the needle tips, accommodating various lengths of MWCNTs. We have performed experiments to test the breaking strength of the MWCNT in the completed device with an atomic force microscope (AFM) tip. An increasing force was applied at the midpoint of the nanotube until failure, which was observed in situ in the SEM. The initial force/deflection data appear promising, and efforts are underway to characterize and improve the strength of the device by conducting more such tests and modifying the welding process.