Nano-Enabled Microfluidic Platforms for Functional Immunomonitoring in Pediatric Sepsis

Pediatric sepsis involves dynamic, developmentally conditioned immune dysfunction that a single cytokine concentration or one-time severity label cannot represent. This structured narrative Review examines how nano-enabled microfluidic systems could support blood-sparing, serial assessment of functional immune states in the pediatric intensive care unit (PICU). We separate soluble-protein concentration, cell phenotype, ex vivo stimulation response, cellular effector function, immunometabolic function, and physiology, linking each measurement class to its evidence level and permitted inference. Direct pediatric studies support the biological relevance of longitudinal antigen-presentation, inducible cytokine, lymphocyte, and metabolic readouts, but cohorts remain few, small, and heterogeneous; secondary-infection findings are conflicting. Recent pediatric studies of serial soluble biomarkers and temperature trajectories expand monitoring evidence but do not validate functional immune trajectories. Engineering studies demonstrate nanoscale capture, amplification, transduction, and low-volume processing, including portable multicytokine sensing, yet these Level 4 results do not constitute pediatric clinical validity. We propose a staged sample-to-answer architecture. It distinguishes patient draw from device input, controls stimulation and preanalytics, retains developmental context, and progresses from analytical validation through pediatric feasibility and clinical validity to prospective prediction and decision utility. Artificial intelligence is restricted to age adjustment, longitudinal modeling, multimodal fusion, uncertainty display, and clinician- or nurse-facing visualization. Within the verified accessible corpus through 16 September 2026, no prospectively validated pediatric longitudinal immune-function trajectory model or nano-enabled functional immune assay for immunomodulatory treatment selection was identified. The near-term objective is a verifiable measurement-and-interpretation pathway, not an autonomous treatment selector, tested in multicenter serial cohorts with transparent blood-volume accounting, independent validation, and PICU human-factors evaluation.