Bio-filter is designed to segregate body fluids into its constituent components like WBC, RBC, platelets from the whole blood using single drop sample of fluid. In this proposed work, separation of biomolecules WBC, RBC and Platelets is possible using passive method based cross flow filtration technique, which is more effective than conventional methods. Separation of biomolecules that are smaller than the microfluidic filter gap size is demonstrated through the sieving medium to filter various sizes of biomolecules with a pre-determined shape and size of microchannel. Filter structure is simple and fluid flow can be achieved without any external force such as electric field, magnetic field, acoustic force, etc. as used in active method. Si material is chosen because of its high biocompatibility. Design is simulated by using COMSOL Multiphysics software. The designed filter can be used for point of care diagnostics and to culture cells.