Acoustophoretic cell and particle trapping on microfluidic sharp edges

Cell and particle trapping experience a rising interest in a microfluidic context. Trapping of cells in suspension at distinct locations in a microfluidic domain is relevant for cell biological lab-on-a-chip systems, where a trap provides a well-definable microenvironment for cell response studies. This paper reports a novel acoustophoretic cell trapping effect on oscillating sharp edge structures which protrude into a microfluidic channel. These edge structures (125-250 $$\upmu \hbox {m}$$ μ m length, 10-80 $$\upmu \hbox {m}$$ μ m width in the experiments) were found to attract cells and particles strongly and reliably upon simple piezoelectric excitation around 1MHz. The method is contact- and label-free, robust, and biocompatible. The physical trapping effect is experimentally characterized, and a numerical model is proposed, based on the theory of acoustic radiation forces