LAUSR

Accuracy and precision velocimetry plays an important role at microfluidic device application, particularly in biomedicine and chemical synthesis. However, most of the developed methods are limited by complicated structure design and microparticle injection. Herein, utilizing a gas bubble generator and remover based on a permeable membrane of polydimethylsiloxane, a simple and convenient microbubble image velocimetry (µBIV) flow sensor has been flexibly designed and integrated into microfluidic device to measure flow rate. Benefited from the contactless of gas channel and fluid channel, this µBIV flow sensor features the bubble generation and removing without fluid invasion in the microchannels, and the formed gas bubbles are stable and can be easily distinguished from the complex matrix. With good stability and reproducibility, this µBIV flow sensor is also successfully demonstrated to long-term and real-time measure the flow rate of the whole blood, which has a board application prospect and may pave the way to develop devices with better performance.