A Simple Approach to Characterize Gas-Aqueous Liquid Two-phase Flow Configuration Based on Discrete Solid-Liquid Contact Electrification.

Dongwhi Choi,Dong Sung Kim,Donghyeon Lee

doi:10.1038/srep15172

Abstract

In this study, we first suggest a simple approach to characterize configuration of gas-aqueous liquid two–phase flow based on discrete solid-liquid contact electrification, which is a newly defined concept as a sequential process of solid-liquid contact and successive detachment of the contact liquid from the solid surface. This approach exhibits several advantages such as simple operation, precise measurement, and cost-effectiveness. By using electric potential that is spontaneously generated by discrete solid–liquid contact electrification, the configurations of the gas-aqueous liquid two-phase flow such as size of a gas slug and flow rate are precisely characterized. According to the experimental and numerical analyses on parameters that affect electric potential, gas slugs have been verified to behave similarly to point electric charges when the measuring point of the electric potential is far enough from the gas slug. In addition, the configuration of the gas-aqueous liquid two-phase microfluidic system with multiple gas slugs is also characterized by using the presented approach. For a proof-of-concept demonstration of using the proposed approach in a self-triggered sensor, a gas slug detector with a counter system is developed to show its practicality and applicability.

Highlights

Tens to hundreds of micrometers, investigating and characterizing a two-phase flow inside a microfluidic channel are crucial but challenging problems in this field
Electric potential is spontaneously generated by the net charge on the gas–solid contact surface in the microfluidic channel based on the same mechanism of the spontaneous charging of an aqueous droplet that detaches from the inner surface of the pipette tip[22]
Given that the net electric charge is spontaneously generated on the microfluidic channel substrate as a gas slug passes through the channel, measuring the spontaneously generated electric potential caused by the electric charge on the substrate with the gas slug can be a simple indirect approach for characterizing the flow configuration

Summary

Introduction

Tens to hundreds of micrometers, investigating and characterizing a two-phase flow inside a microfluidic channel are crucial but challenging problems in this field. Electric potential is spontaneously generated by the net charge on the gas–solid contact surface in the microfluidic channel based on the same mechanism of the spontaneous charging of an aqueous droplet that detaches from the inner surface of the pipette tip[22]. Given that the net electric charge is spontaneously generated on the microfluidic channel substrate as a gas slug passes through the channel, measuring the spontaneously generated electric potential caused by the electric charge on the substrate with the gas slug can be a simple indirect approach for characterizing the flow configuration. It exhibits the practicality and applicability of the proposed approach Given that this pioneering approach enables easy characterization of two-phase flow configuration by introducing an additional electrode to the conventional microfluidic chip, it exhibits several advantages including simple operation, precise measurement, self-triggering, and cost-effectiveness

Methods

Results

Conclusion