into two matching tunneling microelectrodes 11 separated by the width of the nanochannel 30 as shown in fig3 in the nanochannel system shown in fig3 the nanochannel 30 on the silicon chip 5 was mechanically machined in a dimension 3100 afm veeco inc ca controlled by a nanoscope iila controller the afm probe used was an all diamond nanoindenting tip 3 pdnisp from veeco with a calibrated spring constant of 215 n m and a nominal tip radius of 40 nm the tip 3 is mounted on a cantilever 1 which is actuated by piezoelectric tubes pzt 1 fig4 demonstrates the basic layout of the afm machining method in this method the afm tip 3 is pressed against the silicon oxide surface layer 4 of the silicon chip 5 with a constant force by automatically adjusting the pzt 1 to keep the vertical deflection as sensed by the position sensing device psd 6 constant and then translated along a preplanned path on the surface prior research to determine the relationship between the afm control parameters and the resultant nanochannel dimensions is described in z q wang s tung n d jiao et al u201c nanochannels on silicon oxide surface fabricated by atomic force microscopy u201d proceedings of the 2010 5th ieee international conference on nano micro engineered and molecular systems jan 20 23 2010 xiamen china pp.