Miniaturized scalable arrayed CRISPR screening in primary cells enables discovery at the single donor resolution.

High-efficiency gene editing in primary human cells is critical for advancing therapeutic development and functional genomics, yet conventional electroporation platforms often require high cell input and are poorly suited to parallelized experiments. Here we introduce a next-generation digital microfluidics (DMF) electroporation platform that enables high-throughput, low-input genome engineering using discrete droplets manipulated on a planar electrode array. The system supports 48 independently programmable reaction sites and integrates seamlessly with laboratory automation, allowing efficient delivery of CRISPR-Cas9 RNPs and mRNA cargo into as few as 3,000 primary human cells per condition. The platform was validated across diverse primary human cell types and cargo modalities, demonstrating efficient delivery of various cargo, with high rates of transfection, gene knockout via non-homologous end joining, and precise knock-in through homology-directed repair. To showcase its utility in functional genomics, we applied the platform to an arrayed CRISPR-Cas9 screen in chronically stimulated human CD4⁺ T cells, identifying novel regulators of exhaustion, including epigenetic and transcriptional modulators. These findings establish our DMF-based electroporation platform as a powerful tool for miniaturized genome engineering in rare or precious cell populations and provide a scalable framework for high-content genetic screening in primary human cells.