Fabricated solid-state nanopore chips are used to probe individual single stranded DNA (ssDNA) homopolymers. Based on the analysis of the current blockage caused by DNA translocation through a voltage-biased nanopore, we discovered that the hydrodynamic diameter of ssDNA homopolymer helix is comparable to that of double stranded DNA (dsDNA) helix. This proof-of-principle demonstration shows that solid-state nanopore technology can be used to spy on secondary structures of biopolymers. We also show that ssDNA manifests slower and distinct translocation kinetics in comparison to dsDNA. Furthermore, the present study helps to refine our understanding of the ssDNA translocation kinetics through narrower alpha-hemolysin protein pores.