On-chip cell labelling and washing by capture and release using microfluidic trap arrays

Flow cytometry analysis requires a large amount of isolated, labelled, and purified cells for accurate results. To address the demand for a large quantity of cells prepared in a timely manner, we describe a novel microfluidic trap structure array for on-chip cell labelling, such as intracellular and extracellular labelling, and subsequent washing and release of cells. Each device contains 7×104 trap structures, which made the preparation of large numbers of cells 3×105 possible. The structure has a streamlined shape, which minimizes clogging of cells in capture and release steps. The trap structure arrays are built and tested using leukocytes, with different load flow speeds, incubation times, and release flow speeds. 85% of cells are captured independent of the input flow speed. The release efficiency depends on the incubation time, with over 80% of captured cells released for up to 20 min incubation, and on-chip labelling and washing with STYO13 are demonstrated. Qualitative models are developed as guidance for designing the proposed trap structure and to explain the increased performance over previous approaches.