Microfluidic Bubble Point Measurement Using Thermal Nucleation

Abstract

We present a highly miniaturized sensor for performing accurate on-chip detection of gas equilibration (bubble point) pressures in liquids, which is manufactured using low-cost batch microelectromechanical system technology. The measurement of gas equilibration (bubble point) pressures in liquids has a diverse spectrum of applications ranging from the oil industry, where the bubble point of a crude oil is important for making informed decisions on production and exploration, to the fisheries industry, where gas saturation needs to be controlled to ensure animal health. Oilfield measurements of bubble point pressures often require acquisition of large sample volumes that are subsequently investigated off-line in laboratory facilities, with important consequences on both cost and operational response times. The present work demonstrates the potential of microelectromechanical system technology to respond to such diverse industry needs by providing an economical solution able to perform in situ real-time monitoring of gas equilibration pressures with significantly reduced equipment size and analysis time. By implementing rapid on-chip local heating using an integrated platinum electrode and subsequently observing the fluid behavior—either microscopically or with embedded thermal conductivity sensors—we show that we can effectively overcome the nucleation barrier and perform highly accurate, repeatable measurements of the bubble point pressure.