Underwater Bubble Detection and Counting By a Dynamic Changing Solid-Liquid Interfacial Process

In this paper, a dynamic changing solid-liquid interfacial process was used for electrically detecting and counting underwater bubbles. The measurement system consists of a detection electrode, a reference electrode, an electric resistor connected in series with the two electrodes, a differential amplifier and a data acquisition system. Once a bubble touches the detection electrode submerged in a solution, the electrode-liquid interface is changed to the electrode-bubble interface. During this process, an electric pulse is generated and consequently be detected and counted by the measurement system. The generated electric signal is due to the dynamic change of the electric double layer (EDL) of the detection electrode. Experimental results show that the magnitude of the generated signals depends on bubble size, bubble rising height, exposed area of the detection electrode in solution and bubble-contacting position at the electrode. The magnitudes of the generated signals are larger in 3.5% NaCl solution than in pure water. Detection of air bubbles of 0.3 mm in diameter was achieved with a 3 mm x 3 mm detection electrode. The measurement system presented in this paper is simple and has a great potential on sensing and counting underwater bubbles, for applications such as underwater pipe leakage detection and bubble sensing in chemical engineering science.

Automated summary

This paper introduces a method for electrically detecting and counting underwater bubbles using a dynamic changing solid-liquid interfacial process. Experimental results show that the magnitude of the generated signals depends on various factors, and the signals are larger in 3.5% NaCl solution than in pure water. The measurement system has potential applications in underwater pipe leakage detection and bubble sensing in chemical engineering science.