Three-Dimensional Printed Liquid Diodes with Tunable Velocity: Design Guidelines and Applications for Liquid Collection and Transport

TL;DR

This paper introduces 3D-printed liquid diodes that enable unidirectional flow of liquids over long distances, with tunable velocity, useful for applications like fog harvesting and liquid transport, supported by experiments and simulations.

Contribution

The study presents a novel design of 3D-printed liquid diodes with tunable flow velocity, combining experimental and simulation analysis to guide fabrication for specific applications.

Findings

Achieved flow velocities of several mm/sec over tens to hundreds of mm.

Design principles include channel widening and a small bump for unidirectional pinning.

Validated the diode's use in fog water condensation and uphill transport.

Abstract

Directional and self-propelled flow in open channels has a variety of applications, including microfluidic and medical devices, industrial filtration processes, fog-harvesting and condensing apparatuses. Here, we present versatile three-dimensional (3D)-printed liquid diodes that enable spontaneous unidirectional flow over long distances for a wide range of liquid contact angles. Typically, we can achieve average flow velocities of several millimeters per second over a distance of tens to hundreds of millimeters. The diodes have two key design principles. First, a sudden widening in the channels' width, in combination with a small bump, the pitch, ensure pinning of the liquid in the backward direction. Second, an adjustable reservoir, the bulga, is introduced to manipulate the liquid velocity with differing expansion angles. Using a combination of experiments and lattice Boltzmann simulations, we provide a comprehensive analysis of the flow behavior and speed within the channels with varying contact angles (CA), pitch heights and bulga angles. This provides guidelines for the fabrication of bespoke liquid diodes with optimal design for their potential applications. As a feasibility investigation, we test our design for condensation of water from fog and subsequent transport uphill.