Decoding Cellular Heterogeneity with Microfluidic Single-Cell Secretion Analysis Tools.

Cellular heterogeneity is a fundamental determinant of diverse physiological and pathological processes, yet its functional manifestation, the dynamic secretion of proteins, remains challenging to interrogate on the single-cell level. Traditional methods, while invaluable, are constrained by limited multiplexing capacity, inadequate temporal resolution, and reliance on specialized infrastructure, impeding the comprehensive dissection of cellular diversity. Microfluidic technologies have emerged as transformative platforms that address these limitations, enabling high-throughput, multiparameter secretion profiling with spatiotemporal precision. This review systematically synthesizes recent advances in microfluidic single-cell secretion analysis. We first examined the conceptual framework underlying cellular heterogeneity and the inherent constraints of conventional approaches. Subsequently, we analyze core microfluidic principles for single-cell manipulation, focusing on microstructures for isolation and strategies for capturing and quantifying the secreted proteins. We then explored the expanding applications of these technologies across biological and biomedical research. Finally, we discuss emerging opportunities at the convergence of microfluidics with multiomics integration and artificial intelligence, outlining future trajectories for this rapidly evolving field.