Microfluidic System for Rapid Enumeration and Detection of Microparticles

A microfluidic system for rapid concentration, enumeration, and size based detection of microparticles is presented. The system includes a micro flow cytometer chip together with fluidics, optics and control on a single platform. The micro flow cytometer chip was designed, fabricated, and integrated with fluidics and optical fibers. The flow microchannel employs chevron structures at the top and bottom surfaces of the channel to achieve two-dimensional flow focusing. The system employs a cross-flow filter for sample concentration thus enabling enumeration and detection of microparticles even at low concentration levels (∼1.1 × 10⁴/ml). A flow stabilizer chip based on the concept of a fluid chamber with a flexible membrane as the top wall was used to reduce flow pulsations within the fluidic system thus improving measurement accuracy. The excitation optical fiber is connected to a laser source and the collection fibers are connected to photomultiplier tubes (PMTs) for signal manipulation and conversion. Labview was used for data acquisition through a PC interface. The ability of the system for enumeration and size-based detection of microparticles was demonstrated using polystyrene microbeads suspended in PBS as the sample.