Microfluidic profiling of suspension cell-metal adhesion at single-cell resolution under flow

Metallic implants used in vascular applications must maintain functionality under dynamic blood flow conditions. A critical factor affecting their performance is the unintended adhesion of blood cells, including red blood cells (RBCs), to the implant surface-a process that can initiate hemolysis, thrombosis, or inflammation. Despite the clinical relevance, current adhesion assays are not well-suited for suspension cells under flow and typically lack single-cell resolution. In this study, we present a microfluidic platform integrated with metallic electrodes and an external circuit, designed to assess cell-metal adhesion by measuring cell transit velocity under flow. It enables rapid, high-throughput quantification of adhesion affinity at the single-cell level. Notably, the platform reveals marked heterogeneity in RBC adhesion affinity to molybdenum, clearly captured through single-cell transit velocity distributions. We also confirm that adhesion is further shown to be influenced by both surface oxidation of molybdenum and inter-individual variation. These findings highlight the importance of controlling surface characteristics in implant design and support the platform's utility in personalized evaluation of implant materials. While this study focuses on RBCs, the platform could be broadly applicable to other cell types, including both suspension and adherent cells.