Biofluids remain a difficult issue in some drug delivery processes for separation of bioparticles through microchannels. This chapter reviews the techniques which have been substantiated and proven helpful for the separation of particles depending on mass and size with some constraints of high throughput. In this study, a key focus will be on separation criterion by patterning of a microchannel and utilize sieve type channels based on spherical bioparticles. The first part focuses on the designing of the pattern for issues of the network like clogging and theoretical experiments by both hydrodynamic and other passive methods for sorting/separation. The second part focuses on the simulations for separation for small and larger bio particles depending on mass and size, samples of blood and other Klebsiella infected fluidic samples for the experiment. The theme provided for mass and size-based separation is simple and can accomplish operations in microfluidics for several biological experiments, diagnosis approaches and zoological researches.