A team at the Institute for Bioengineering of Catalonia (IBEC) has created a new device called XpertBiofilm, designed to mimic the natural environments in which biofilms grow and to test how effective antibiotics are against them. Biofilms are clusters of bacteria that stick to surfaces and surround themselves with a sticky, protective layer. This makes them much more resistant to antibiotics and the immune system than bacteria that are free-floating. They are often responsible for long-term infections in people with conditions like cystic fibrosis, chronic obstructive pulmonary disease (COPD), and chronic wounds, as well as infections related to catheters and prosthetic devices. The growing problem of antibiotic resistance has made it increasingly important to find better ways to predict which treatments will work best for individual patients. Most current lab systems for studying biofilms use static plates, where the liquid doesn't move. However, in the human body, bacteria typically grow in environments with fluid movement, such as blood or mucus. This movement creates a kind of friction known as shear stress, similar to the force a stone feels in a flowing river. Researchers at IBEC studied this shear stress at a microscopic level, focusing on how moving liquid affects bacteria that stick to surfaces. Existing devices that can replicate this flow are often complicated, costly, and require specialized equipment and trained personnel, which limits their use. To solve this, the IBEC team designed XpertBiofilm with a growth chamber that uses a specific shape to create even, controlled flow over a small, removable piece (a round coverslip) where biofilms form. Once the biofilm has developed, the coverslip can be analyzed directly using a standard microplate reader, which means no expensive microscopes are needed. XpertBiofilm can simulate a range of flows from 0.02 to 0.9 mPa, which matches the low-shear-stress conditions found in the lungs of cystic fibrosis patients. In tests, the researchers found that within this range, higher flow increased the amount of biofilm formed by Pseudomonas aeruginosa, a bacteria commonly found in chronic wounds and medical device infections. This explains why P. aeruginosa adheres strongly to airways in cystic fibrosis patients and why the lungs are less able to clear these bacteria, leading to persistent infections. The team also used XpertBiofilm to test whether antibiotics could effectively kill existing biofilms, using P. aeruginosa strains with different resistance patterns. They also tested sputum samples directly from cystic fibrosis patients, without isolating individual bacteria in the lab. In both cases, the device accurately predicted which antibiotics would be most effective, matching the known resistance patterns of the samples. The researchers emphasize that this study was a preliminary laboratory test using a limited number of bacterial strains and patient samples. Before XpertBiofilm can be used regularly in clinical settings, it needs to be tested with more samples and different types of bacteria. For now, the device is being proposed as a supplementary tool to current diagnostic methods, potentially helping doctors choose more effective, personalized antibiotic treatments for patients.