The pulling force profile during ssDNA translocation also exhibits apparent peaks (Fig. 4(a)), each still corresponding to a nucleotide but with distinct peak values, in sharp contrast with the nearly identi- cal values for the ssDNA A6 (Fig. 2(b)). It was also found that nearly all the G bases occupy the highest peaks and that most peak forces for pyrimidine bases (C and T) are remark- ably lower than those for purine bases (A and G). This origi- nates from the distinct geometries of nucleobases: the pyrimidine bases are six-membered rings containing nitrogen atoms and carbon atoms, whereas the purine bases are both fused five- and six-membered heterocyclic compounds that significantly impede their passage through the nanopore and increase the peak force values. Similar results were also obtained in additional eight tested DNA sequences (Fig. S3 in supplementary material16). To further address this issue, we summarized in Fig. 4(b) the averaged peak forces over the same nucleotides from the above nine sequences. It can beseenthatthepeakforcesforA,G,andCorT(CandT, however, remain indistinguishable) have distinct values. The distinct peaks for A, G, and C or T suggest that they can be readily distinguished from each other, while the nearly iden- tical signals for pyrimidine bases (C and T) indicate that they cannot be differentiated.