High throughput particle separation with a mirrored deterministic ratchet design

• A mirrored deterministic ratchet design provides efficient suspension separation.
• A mirrored design allows displacement of particles to the center or to the sides.
• Separation was found feasible until a critical particle concentration.
• Future applications in concentration and cleaning of suspensions are foreseen.

Deterministic ratchets, also called lateral displacement arrays, consist of periodic arrays of obstacles, spaced such that suspended particles having a minimum size are displaced. They have potential for suspension separation and fractionation. We report on the development of designs with obstacle arrays mirrored along the center plane providing more efficient displacement compared to non-mirrored designs. Depending on the application (e.g. concentration or cleaning) the design can be oriented to the center or to the sides. Highest recovery of incoming particles was found 88% in the center orientation, while the strongest depletions were achieved with the side orientation. Halving the length of the array did not always yield similar separation to the conventional design, especially at higher concentrations. This implies that particle displacement was not pure deterministic, but influenced by stochastic particle–particle interactions. Fractionation experiments demonstrated high recoveries of large particles, which were not much influenced by presence of small particles.