Investigation of the effects of tube geometry in the microfludic device used to generate nanospheres

This study describes polymethylsilsesquioxone (PMSQ) nanospheres formation from microbubble bursting in a 100 µm capillaries embedded combined microfluidic device based on effects of junction angle and flow rate of liquid solution. The understanding of polymer nanosphere generation from microbubble bursting in the device with thin capillaries used could be very useful for many applications, such as cell transplantation in biomedical therapy, advanced therapeutic applications and food industry. The effects of the junction angle (Ø=0° to 60°) between the liquid and gas channels and the gas pressure ratios (50 to 400 kPa) are considered. The digital microscope results indicate that the microbubble size during the bubble generation process generally decreases with the increase of junction angle at the same flow rate and gas pressure. A junction angle of around 60° was figured out as the most efficient angle at which alternating microbubbles are still formed at lower capillary numbers (Ca). In addition, the nanosphere size in the combined microfluidic junction device with 100 µm capillaries decreases as junction angle increases with the same flow and gas pressure conditions. The microbubble formation in the device used in this work depends sinificantly on the gas pressure, and the combined microfluidic junction device with thin capillaries becomes a microbubble generation when N2 gas pressure is greater than 50 kPa.