Production of Single-Cell-Laden Alginate Microgels Through Seamless Separation and In-Flow Gelation Using Deterministic Lateral Displacement

Cell-laden alginate microgels have been extensively studied for three-dimensional cell culture, tissue engineering, and cell-based screening because they provide microscale compartments that support cell culture in a defined microenvironment. In particular, single-cell-laden alginate microgels have attracted increasing interest as platforms for studying cellular heterogeneity. These applications require efficient and scalable production of single-cell-laden alginate microgels. Droplet microfluidics has therefore emerged as a promising method for producing alginate microgels with high uniformity and throughput. However, conventional passive encapsulation is governed by Poisson statistics, resulting in a large fraction of empty alginate microgels and only a limited fraction containing a single cell. Consequently, additional pre- or post-processing steps, such as cell pre-coating or off-chip purification, are often required, complicating the workflow and reducing process continuity. In this study, we propose a microfluidic device that integrates continuous separation of cell-encapsulated droplets with ionic gelation in a deterministic lateral displacement (DLD) micropillar array. This integrated design allows for the seamless production of single-cell-laden alginate microgels with improved purity. As a proof of concept, we demonstrated the continuous production of single-cell-laden alginate microgels using NIH3T3-3-4 as a model cell line, with a purity of 64% and a separation efficiency of 53%. These results show the potential of DLD-based integration for the streamlined and scalable production of single-cell-laden alginate microgels for single-cell analysis and related advanced biomedical applications.