A Novel Spiral Microfluidic Device for Urinalysis

Urinalysis is transforming the field of disease diagnostics through its wide range of capabilities in detecting diseases such as proteinuria, diabetes, and kidney dysfunction. Identification of urine sediment particles (such as white blood cells, red blood cells, cast, crystal, and yeast) is critical since their presence in a urine sample indicates a number of possible medical conditions such as kidney stones, diabetes, and even tract infections. The need for advanced microfluidic devices is expanding as demands for more effective detection methods of urinary tract infections and disorders increase. In this project, a novel spiral microfluidic device is developed for automatic urine sediment particle separation followed by morphology analysis.

This device was designed based on the principle of inertial separation using a spiral microchannel that led to particle separation based on their difference in mass, size, and inertial property. Particles in urine vary in size and mass. The device was fabricated using soft lithography technology and tested using human urine samples.  The urine particles traveled through the spiral microchannel and were separated based on varying inertial characteristics into the corresponding tangent branches. A mathematic model of this separation method involving the formation of dean vortices was established. Using this device, several types of urine particles were successfully sorted and separated, followed by particle morphology study under a microscope. Separation efficiency was determined. The experiments showed that the inertial separation technique using the spiral microchannel is more effective than the other leading separation methods such as microfiltering.