Organic Electrochemical Transistors for Rapid Point-of-Care Detection of Heart Failure Biomarkers

Abstract

Heart failure (HF) affects approximately 6.7 million individuals in the United States alone, with its global prevalence projected to double by 2050. Early detection remains challenging, as many patients are unaware of their condition until severe symptoms emerge, often after the window for effective intervention has narrowed. NT-proBNP, a key biomarker for HF, is typically measured using fluorescence immunoassays, which are costly, time-consuming, and not well suited for point-of-care (POC) use. This thesis addresses these limitations through the development of a scalable and affordable POC diagnostic platform based on fully inkjet-printed planar-gated organic electrochemical transistors (OECTs) integrated with passive blood filtration for direct NT-proBNP detection from whole blood. OECT-based biosensors have emerged as promising platforms due to their high transconductance, biocompatibility, and compatibility with aqueous operation; however, their translation remains limited by fabrication complexity, device stability, and integration with real-world sample handling. We optimized device geometry and surface chemistry to enhance OECT performance and sensing robustness, characterized sensor performance in human plasma, and assessed sample preparation strategies compatible with finger-prick blood volumes. Substrate modification reduced the printed channel length to 9.5 µm, below the nominal resolution limit of inkjet printing, yielding a peak transconductance of 84 mS, among the highest reported for printed OECTs at this footprint. Functionalized sensors achieved a limit of detection of approximately 45 pg/mL in human plasma, with statistically significant discrimination (p < 0.001) across all guideline-defined clinical cutoffs. Plasma separation membranes sized for finger-prick blood volumes achieved 99.84% red blood cell removal while maintaining reliable transistor performance, confirming compatibility with the OECT sensing workflow. Together, these results establish inkjet-printed PEDOT:PSS-based OECTs with integrated plasma filtration as a scalable route toward affordable, finger-prick-compatible POC heart failure diagnostics.