Circulating tumor cells(CTCs)shed from either primary or metastatic cancers have been identified in the peripheral blood of patients,and are often associated with cancer metastasis and tumor recurrence.In this work,we design a double spiral microchannel with 6-spiral loops for each direction with a very low aspect ratio to enrich the tumor cells from blood in a label-free manner.1 When the magnitude of Dean drag is comparable to that of inertial lift forces,cells are focused to a single equilibrium position or array due to the secondary flow,resulting in different equilibrium positions for small blood cells and large tumor cells.2 After cell separation,nucleic acids from MCF-7 cells were extracted and detected by loopmediated isothermal amplification(LAMP).Nanoprecipitation is a simple and widely used method to prepare nanoparticles.This method typically uses water-miscible solvents to dissolve polymer,and dips the polymer solution slowly into water with sonication or stirring.3 Here we synthesize PLGA nanoparticles at low and high flow rates in a microfluidic device.PLGA nanoparticles of a small size of approximately 55 nm are obtained at a high flow rate(410 mL/hr,Re = 650)and a large FR(40).The size of nanoparticles increases to around 70 nm by adjusting the FR to 20.If we further decrease the FR to 10,a larger size of approximately 135 nm is achieved.Both TEM and DLS results indicate a good dispersion of PLGA nanoparticles.