Microfluidic Capillaric Circuit for Rapid and Facile Bacteria Detection

Urinary tract infections (UTI) are one of the most common bacterial infections and would greatly benefit from a rapid point-of-care diagnostic test. Although significant progress has been made in developing microfluidic systems for nucleic acid and whole bacteria immunoassay tests, their practical application is limited by complex protocols, bulky peripherals, and slow operation. Here we present a microfluidic capillaric circuit (CC) optimized for rapid and automated detection of bacteria in urine. Molds for CCs were constructed using previously established design rules, then 3D-printed and replicated into poly­(dimethylsiloxane). CCs autonomously and sequentially performed all liquid delivery steps required for the assay. For efficient bacteria capture, on-the-spot packing of antibody-functionalized microbeads was completed in E. coli in synthetic urine was 1.2 × 102 colony-forming-units per mL (CFU/mL), which is well below the clinical diagnostic criterion (>105 CFU/mL) for UTI. The self-powered, peripheral-free CC presented here has potential for use in rapid point-of-care UTI screening.