ABSTRACT
Two polystyrene (PS) probes, and one polyethylene (PE) probe were used in this study. The PS probes consisted of 10 ± 1 jim diameter PS beads glued to regular v-frame ContactMode cantilevers (Digital Instruments, Santa Barbara, C A , USA) with a nominal spring constant (k) of 0.58 N/m. The PE probe consisted of a 14 ± 2 /xm diameter bead glued to a stiffer v-frame (pre-calibrated) cantilever having a nominal k value of 17.0 N/m, and was provided by Bioforce Nanosciences (Ames, IA, USA). Spring constants provided by the suppliers of the cantilevers were used in analysis of the data, and no measurement to confirm the accuracy of claimed values was performed in this research.
