Electron Tractor Beam: Deterministic Manipulation of Liquid Droplets on Solid Surfaces

Abstract

The motion of liquid droplets is studied across many physics subfields and manipulation of nanoscale droplets on demand holds great promise in, e.g., nanotechnology. In this study, AuGe droplets on a germanium substrate are manipulated by an electron beam in a scanning electron microscope. The electron beam exposure creates a local temperature gradient in a substrate and induces a directional thermomigration of droplets nearby. To quantitatively analyse this phenomenon and to reveal the mechanism behind it, experimental observations under different conditions (beam current, sample temperature, scanning strategy) and simulations are combined. The obtained insights suggest that the droplet motion is limited by the dissolution of the substrate below the droplet. In addition, it is shown that the electron tractor beam is not only able to control the droplet motion but can also be used to split the droplets, thus opening new possibilities for droplet manipulation inside an SEM.

Airflow Triggered Water Film Self-Sculpturing on Femtosecond Laser-Induced Heterogeneously Wetted Micro/Nanostructured Surfaces

“…Research of super lubricated and superhydrophobic surfaces has matured and examples have been greatly improved over time. − Manabe et al utilized lubricating fluid and a light-responsive liquid layer, fulfilling droplet manipulation through UV light . The droplet surface tension lost its balance when a UV light shines on a side of the droplet and started to move along the direction opposite the light.…”