Soft Robotic Concepts in Catheter Design: an On‐Demand Fouling‐Release Urinary Catheter

Abstract

Infectious biofilms are problematic in many healthcare-related devices, and are especially challenging and ubiquitous in urinary catheters. This report presents an on-demand fouling-release methodology to mechanically disrupt and remove biofilms, and proposes this method for the active removal of infectious biofilms from the previously-inaccessible main drainage lumen of urinary catheters. Mature Proteus mirabilis crystalline biofilms detach from silicone elastomer substrates upon application of strain to the substrate, and increasing the strain rate increases biofilm detachment. The study presents a quantitative relationship between applied strain rate and biofilm debonding through an analysis of biofilm segment length and the driving force for debonding. Based on this mechanism, hydraulic and pneumatic elastomer actuation was used to achieve surface strain selectively within the lumen of prototypes of sections of a fouling-release urinary catheter. Proof-of-concept prototypes of sections of active, fouling-release catheters were constructed using techniques typical to soft robotics including 3D printing and replica molding, and those prototypes demonstrate release of mature P. mirabilis crystalline biofilms (e.g., ≈90%) from strained surfaces. These results provide a basis for the development of a new urinary catheter technology in which infectious biofilms are effectively managed through new methods that are entirely complementary to existing approaches.

Pathogenesis of Proteus mirabilis Infection

“…Multiple groups are developing new approaches to prevent biofilm establishment, including alternative catheter materials, antimicrobial coatings or instillation of anti-biofilm chemicals, mechanical or electrical biofilm dispersal, bacteriophage, and control of urinary pH (278, 285–287). Because P. mirabilis is the major agent of crystalline biofilm formation and catheter blockage during CAUTI, many of these efforts focus on this species.…”

Nanoscience‐Based Strategies to Engineer Antimicrobial Surfaces

“…[81] These act as barriers against invading particles, since dynamic deformation and cilia provide unstable surfaces that are unfavorable for bacterial attachment. [84] The presence of external stimuli, such as hydraulic or pneumatic actuation, results in repeated deformation of the inner surface of the catheter and the active removal of >80% infectious biofilms. [82] Investigations of the effectiveness of dynamic surfaces driven by pneumatic actuation against marine biofouling have demonstrated biofilm detachment (>90%) in both laboratory and field environments.…”

Proteus mirabilisand Urinary Tract Infections

“…These include the use of catheters impregnated with combinations of chlorhexidine, silver sulfadiazine, and triclosan; the use of urease inhibitors to prevent crystalline biofilm formation; and the treatment of catheters with a cocktail of bacteriophages (6, 268). Most of the techniques tested have been chemical, not mechanical, which makes the promising in vitro results using low energy acoustic waves to prevent bacterial attachment and the development of a urinary catheter that uses inflation-generated catheter strain to clear P. mirabilis crystalline biofilms intriguing alternative approaches (268, 269). …”