High-throughput weak-current measurements of single nanoparticles using optical vortex and double-slit structures

In recent, nanoparticle identification technologies have attracted much attention in various research fields, where further high throughput and high accuracy of measurements are required. Herein, we propose a novel method to analyze single nanoparticles using a double-slit structure embedded in a nanochannel and an optical vortex. Single gold particles with a diameter of 200 nm are captured and manipulated by an optical vortex. Under an ionic current condition, the orbital motion of a particle around a double-slit structure is recognized by electrical spike signals, which achieves a sampling frequency over 30 Hz and works well to improve the measurement accuracy. It is suggested that the amplitude of the current pulse depends on the salt concentration and particle trajectory in liquids. Taking account of these factors, a relationship between the electrical signals and particle behavior is discussed.