Microfluidic chip with integrated separation, mixing, and concentration operations for rapid and sensitive bacterial detection utilizing synthetic inorganic antibodies

Abstract

In this paper, we presented a microfluidic chip that integrates bacterial separation, mixing, and concentration solely through fluid dynamics. Size-based bacterial separation was achieved through Dean flow and inertial focusing by harnessing the attributes of a spiral-shaped fluidic channel. Furthermore, Dean flow was capitalized upon to enable the mixing of bacteria with the detection substance, complemented by the integration of PDMS membrane filter for bacterial concentration, all unified within the chip architecture. The performance of individual components was validated using E. coli. In the separation experiment between 4.1 µm particles and E. coli, a separation efficiency of 87.07 ± 2.21% was measured for E. coli, and the mixer demonstrated a mixing efficiency of 92.8% at 30 μL/min flow rate. Concentrating E. coli through the filter for 30 min yielded an average loss rate of 7.47%. Moreover, the proposed microfluidic device was applied for bacterial detection using both our in-house-developed inorganic synthetic antibodies and commercially available fluorescent antibodies. Real-time optical measurements demonstrated the potential of the chip for cost-effective, rapid, and sensitive bacterial detection. The versatility of the chip was substantiated by its successful implementation for the E. coli detection at a concentration of 102 CFU/mL in spiked urine samples.