Biofi lms, groups of bacteria that adhere to wet surfaces and resist antibiotics, often cause chronic infections and complications

with medical devices. Despite their critical role in various environments, a signifi cant gap remains in understanding biofi lm

dynamics within common ecological settings. Here, we investigate the formation and development of biofi lm streamers in

microfl uidic channels using Pseudomonas aeruginosa PAO1 and its chemotaxis-blind mutant PC4. We fi nd that biofi lm

streamers consistently form at the corners of microfl uidic channels under low-speed fl ow conditions. We observe that higher

concentrations of LB medium lead to the development of mature biofi lms, while lower concentrations favor the formation of

streamers. Also, the surface properties of the microfl uidic channels signifi cantly infl uence biofi lm formation. The PEL-coated

surfaces are more favorable to form biofi lm streamers compared to bare glass surfaces. Furthermore, we investigate the role

of chemotaxis with wild-type PAO1 strains formed streamers diff erently compared to the PC4 mutant, which confi rms that

chemotaxis signifi cantly impacts streamer formation. These fi ndings off er valuable insights into the physical and biological

factors aff ecting biofi lm development in microfl uidic environments and provide important information for further studies

on bacterial biofi lms.