A method for separating cells in a biofluid includes pretreating the biofluid by introducing an additive, flowing the pretreated biofluid through a microfluidic separation channel, and applying acoustic energy to the microfluidic separation channel. A system for microfluidic cell separation, capable of separating target cells from non-target cells in a biofluid includes at least one microfluidic separation channel, a source of biofluid, a source of additive, and at least one acoustic transducer coupled to the microfluidic separation channel. A kit for microfluidic cell separation includes a microfluidic separation channel connected to an acoustic transducer, a source of an additive, and instructions for use.
