Fig. 5: Example molecular sensing using 15-nm MPSN.
From: In-tube micro-pyramidal silicon nanopore for inertial-kinetic sensing of single molecules
a Current blockade signals (right) of six representative macromolecules measured at a voltage bias of 0.6 V and respective pH values of their balanced states in 1 M KCl solution under rotation speeds of 2000 rpm (blue) and 4000 rpm (red). Corresponding molecular/protein structures (left, from Protein Data Bank) are shown in front and top views. β represents the length-to-diameter ratio of the molecule (i.e., r/R), where r and R are the polar and equatorial semi-axis of a molecule, respectively. IRMS indicates the root-mean-square current noise of each measurement. b Mass and shape distribution of tested molecules. A shape-to-mass weighting factors (ξ), i.e., K′/m can be deifined for discriminating the six macromolecules. Here K′ is the shape factor determined solely by β, m is molecular weight. Duration t1 (c, d) and t2 (e, f) measured at two rotation speeds, i.e., 2000 rpm (c, e) and 4000 rpm (d, f). Fitted curves (black) indicate that duration t1 linearly increase with ξ while duration t2 decrease exponentially with m. Error bars in c–f represent the standard deviations of experimental data measured from the blockade signals.
