Tracking single-particle dynamics via combined optical and electrical sensing

While fluorescent imaging has been extensively used for single-particle tracking, temporal and spatial resolution of the wide-field microscopy technology is not satisfactory for investigating fast-moving features. Here we report a method for probing nanometer-scale motion of an individual particle through a microstructured channel at sub-MHz by combining a resistive pulse technique to the optical sensing. We demonstrate unambiguous discriminations of translocation and non-translocation events inferred from spike-like electrical signals by fluorescence images captured synchronously to ionic current measurements. We also find a trajectory-dependent translocation dynamics of voltage-driven single-particles through a microchannel. This electrical/optical approach may find applications in sensor technologies based on micro- and nano-electromechanical systems.