Temperature-Induced Tunable Particle Separation

An effective approach to isolation of submicrometer-sized particles is desired to separate cancer cells and healthy cells or in therapy for Parkinson's disease and Alzheimer's disease. However, since bioparticles span a large size range covering several orders of magnitude, the development of an adequate separation method is a challenging task. We consider a collection of noninteracting Brownian particles of various sizes moving in a symmetric periodic potential and subjected to external unbiased harmonic driving as well as a constant bias. We reveal a nonintuitive, yet efficient, separation mechanism based on a thermal-fluctuation-induced negative-mobility phenomenon in which particles of a given size move in a direction opposite to the applied bias. By varying solely the temperature of the system, one can separate particles of various strictly defined sizes. This approach may be an important step toward the development of point-of-care lab-on-a-chip devices.