Conversion of Surface Energy and Experimental Investigation on the Self-Motion Behaviors of Liquid Droplets on Gradient Surfaces

Abstract

A surface with surface energy gradient was fabricated by using a controlled photodegradation technique of a fluoroalkylsilane self-assembled monolayer (SAM) using irradiation of vacuum ultraviolet light (wavelength=172 nm). Visualization experiments were carried out to investigate the motion behaviors of water droplets on horizontal gradient surfaces. System free energy conversion was analyzed to understand the mechanics of the droplet self-motion. The results show that the liquid droplets were self-propelled to move from hydrophobic region to hydrophilic region on horizontal gradient surfaces. The motion process of the water droplet experienced an accelerating stage and a decelerating stage. The velocity of 2 mL water droplet reached to a maximum of 23.28 mm/s. In the droplet motion on the horizontal gradient surface, the deformation and spread of the droplet continuously release out the interfacial and gravitational potential energy, which offers the kinetic energy for the droplet motion. However, the released interfacial energy is three orders of magnitude larger than the released gravitational potential energy. Thus, the released interfacial energy is the main source of driven energy for the droplet motion. The theoretical analysis is consistent with the experimental results.

Advances in Engine Efficiency: Nanomaterials, Surface Engineering, and Quantum-Based Propulsion

“…Here, we investigate the prospect of inducing a gradient in a material's refractive index by the use of entangled photon pairs, so producing a net force on a device. Analog to the instances on hydrophobic surfaces, where water droplets appear to be able to defy gravity and go in unexpected directions, we investigate the feasibility of producing propulsion in a material medium [33][34][35][36][37]. In the same way that the hydrophobic effect uses surface contacts to drive motion with gradients of free energy, our theory takes into account the application of quantum entanglement to control a material's refractive index with the goal of applying a net force to an apparatus.…”