Bubble generation and growth mechanism in PMMA microfluidic chip

Bubbles often impede microfluidic chip functionality, especially in areas where heating is required. In this article, the mechanism of bubble generation and growth in polymethyl methacrylate microchannels was analyzed. The sources of bubbles were taken into consideration: (i) dissolved gas in the liquid, (ii) insoluble gas in cavities of the channel, and (iii) the gas produced by the phase change of the liquid. The factors that affect bubbles in microchannels were analyzed, including the liquid flow rate, surface modification of channels, and pressure on the fluid in the microchannel. Three sets of experiments were designed and carried out, and the results demonstrated that the bubbles in the microchannel can be shrunk and even eliminated by improving the flow rate, modifying channel surface properties, and increasing the liquid pressure.