Magnetic smartphone microflow cytometry enables rapid CD4/CD8 T cell quantification

Abstract

Accurate enumeration of CD4+ and CD8+ T lymphocytes is essential for HIV management, yet conventional flow cytometry remains largely inaccessible in resource-limited settings. Current point-of-care testing (POCT) approaches, including lateral flow assays and fluorescence-based imaging methods, offer improved accessibility but typically compromise accuracy and yield semi-quantitative results. Here, we present a magnetic-activated smartphone microflow cytometry (MACC) platform that enables rapid, highly accessible, and fully quantitative T lymphocyte counting at the POCT. MACC integrates microfluidic immunomagnetic cell separation with smartphone-based bright-field imaging, providing high-sensitivity, highly accessible analysis without requiring sophisticated laboratory equipment or fluorescent labels. A degassing-driven microfluidic pumping mechanism ensures stable microflow generation for reliable continuous analysis, while smartphone imaging enables clear differentiation of targeted lymphocytes from non-lymphocytes. The complete assay, including magnetic bead labeling, chip operation, hands-on procedures, and automated cell-counting analysis, is completed within 24 min. Validation with HIV-infected patient samples demonstrated strong concordance between MACC and conventional flow cytometry for CD4+ and CD8+ counts as well as CD4/CD8 ratio measurements, with minimal bias. By combining high accessibility, cost-effectiveness, and ease of operation, MACC represents a promising alternative to traditional methods, facilitating decentralized HIV monitoring and expanding diagnostic accessibility in resource-limited settings.