A method of exchanging fluids with suspended particles includes providing a microfluidic device with a first inlet channel operatively coupled to a source of particles and a second inlet channel operatively coupled to an exchange fluid. A transfer channel is connected at a proximal end to the first inlet channel and the second inlet channel. First and second outlet channels are connected to a distal end of the transfer channel. The source of particles is flowed at a first flow rate into the first inlet channel while the exchange fluid is flowed at a second flow rate into the second inlet channel wherein the ratio of the second flow rate to the first flow rate is at least 1.5. Particles are collected in one of the first and second outlet channels while fluid substantially free of particles is collected in the other of the first and second outlet channels.