Detection of SPM tip-attached DNA molecules with solid state nanopores*

Using an apparatus that combines solid-state nanopores with a scanning probe~microscope (SPM), we studied ionic current reduction due to the SPM tip. The experiment was performed at different KCl concentrations, SPM tip probing heights, and several bias voltages. The same experiment was also performed with DNA molecules attached to the SPM tip. The current blockage signal through solid-state nanopores with and without luDNA molecules attached to the SPM tip was analyzed. We also present the current blockage and electrical field profile simulation using finite element analysis software (Multiphysics, COMSOL Inc).