World’s first liquid-bodied robot eradicates biofilms on complex surfaces

An international research team led by the Chinese University of Hong Kong (CUHK) has developed the world’s first liquid-bodied robot for biofilm eradication on complex surface topographies.

Biofilms are structurally and dynamically complex, and they are resistant to common antibiotics. Medical implants are particularly susceptible to biofilm infection. In 2023, the team developed magnetic microrobots loaded with antimicrobial agents to eradicate recalcitrant biofilm infections. “While the [previous] robots could navigate simple tubular structures, they struggled to adapt to complex surfaces such as medical stents and meshes, leaving residual biofilm,” noted the researchers. [AIMS Microbiol 2022;8:239-277; Adv Intell Syst 2023;2:2300092; Sci Adv 2025;doi:10.1126/sciadv.adt8213]

In partnership with Nanyang Technological University in Singapore and the Max Planck Institute for Intelligent Systems in Germany, the team has developed the world’s first antibiofilm magnetically-controlled liquid-bodied robot to address this issue. Like the previous model, the liquid robot can be delivered via endoscopy and tracked by X-ray fluoroscopy, omitting the need for invasive surgery to access the infected implant. Of note, the liquid-bodied antibiofilm robot has added two new features that aid in eliminating biofilms.

The liquid-bodied robot consists of a dynamically cross-linked magnetic hydrogel with a switchable viscoelastic response. By precisely modulating external magnetic fields, the robot can toggle between two modes: the elastic mode and the liquid mode. In elastic mode, it rotates, rolls, and traverses obstacles. In liquid mode, it transforms into a fluid-like robot, allowing it to seep into tight spaces and eliminate any biofilm present in deep crevices.

“Traditional robots often face a compromise between accessibility and driving force, however, our liquid-bodied robot achieves both,” commented Professor Li Zhang of the Department of Mechanical and Automation Engineering, CUHK. “The adaptability is highly desirable for eradicating biofilm infections on complex surface topographies.”

The liquid-bodied robot also features a triple synergistic antibiofilm mechanism. First, it mechanically disrupts the biofilm matrix. Next, it kills bacteria by releasing antimicrobial agents. Finally, the robot binds to biofilm debris to help prevent biofilm regrowth.

The researchers further evaluated the robot’s performance on biological surfaces with complex topographies, including hernia mesh and metallic biliary stent.  

“The liquid-bodied robot performed exceptionally. The biomass was reduced by 84.25 percent after treatment, suggesting that the robot removed most biofilms colonized on the mesh,” reported Zhang. “Notably, 87.36 percent of bacteria on a metal biliary stent were killed. In a mouse model with infected stents, complete weight recovery was observed within 12 days, with a 40 percent reduction in inflammation indicators vs controls.”

“Biliary biofilm infections have long been a focus of my research. When solidified biofilm completely blocks a patient’s bile duct, conventional therapies often fail,” commented the co-author, Professor Joseph Sung from Lee Kong Chian School of Medicine, Nanyang Technological University. “This liquid robot offers a novel solution. We aim to integrate next-generation antimicrobial agents and validate its efficacy in clinical settings.”