Fig. 2. Nanoparticle manipulation with 1D standing waves.

a Patterning of 100 nm diameter fluorescent polystyrene particles using 1D acoustoelectronic fields on a half-shielded piezoelectric substrate. b A stacked composite of images demonstrating the trapping positions of polystyrene nanoparticles (100 and 400 nm beads) and carbon nanotubes. The bright metal dot (blue arrow) indicates the geometric center between two mirrored IDTs with electric connection in trans-mode (Δφ₁ = π), of which the lateral position is aligned with a displacement node. c Simulation indicating the trapping position of 100 nm polystyrene beads in water. The arrow indicates the direction of the acoustoelectronic forces. Disp. substrate displacement, Volt. voltage in the water chamber. d 1D patterns of 28–970 nm polystyrene beads. e–j Nanoparticle image velocimetry analysis on 100 and 400 nm particles. e–f Time-elapsed distribution of single nanoparticles near the trapping nodes from −λ/4 to +λ/4. Normal fitting curves are used. g, h The influences of excitation amplitudes on the nanoparticle distribution. i The average trajectory of single nanoparticles under a 36.4 Vpp excitation amplitude. j The averaged distance-dependent actuation force on single nanoparticles. Scale bars: 60 μm.