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

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.

Study of Contact Electrification at Liquid-Gas Interface

“…The phenomenon of surface electrification upon contact has been documented for over 2600 years, and many applications have been developed based on this phenomenon. − Since 2012, the triboelectric nanogenerator (TENG) proposed by Wang, which uses the coupling of contact electrification and electrostatic induction to generate electrical energy, has been a further understanding of the mechanism of frictional power and gradually developing as one technology in the field of energy harvesting. − The operation of a TENG mainly relies on the interfacial electrostatic field, which outputs power due to the displacement current induced by mechanical motion. − So far, TENGs can harvest energy from tribo-contacts at the solid-solid interface, − solid-liquid interface, − liquid-liquid interface, , and even solid-gas interface, while the applications of TENGs have also been successfully developed in many areas, including micro/nano power source, − self-powered sensors, − blue energy harvester, − and high-voltage sources. − However, little progress has been proposed related to energy generation at the liquid-gas (L-G) interface. It is commonly known that lightning on rainy days and lightning of dressing coats are the results of triboelectricity, which can be an undeveloped energy source.…”

Development of a highly transparent and flexible touch sensor based on triboelectric effect

“…At this point, an electric signal is generated due to the movement of the induced charges on the electrode layer. Previous Development of a highly transparent and flexible touch sensor based on triboelectric effect studies reported that sensors based on the triboelectric effect can sensitively respond to applied pressure by sensing electric signals differentially generated from varying applied pressures [7,22,23]. Given that the triboelectric effect is ubiquitous, the only requirement of its occurrence is sequential contact and the separation between any two different material surfaces.…”