Acoustophoretic trapping of particles by bubbles in microfluidics

We present in this paper a simple method to produce strategic acoustic particle capture sites microfluidic channels controlled way. Air bubbles are intermittently injected into micro-capillary with rectangular cross section during flow motion of liquid suspensions containing micron-sized particles or create bubble-defined “micro-gaps” size close 200 µm and spheroidal geometry. The establishment 3D standing wave inside the capillary at frequency 1 MHz produces different radiation forces on solid bubbles, streaming around bubble. While sample flows, part collect along pressure node established near central axis continue circulating aligned through until reaching end, where released enriched. Meanwhile, bubble travels very fast toward positions maximum amplitude beside channel wall, driven by Bjerkness forces, attach it, remaining immovable actuation. Some adhere its membrane trapped generated oscillating Changes were applied analyze influence parameter dynamics, which shows complete stability once attached wall. Only increasing induces displacements. Once reached open air end capillary, disappears releasing separated from their initial host suspension purity degree. device presents geometry low-cost fabrication.