Ultrasound-enabled refreshable electrochemical sensors for cardiac biomarker monitoring.

Cardiac troponin I (cTnI) is the gold-standard biomarker for acute myocardial infarction, yet current laboratory-based high-sensitivity assays require centralized infrastructure, trained personnel, and serial testing, limiting their suitability for real-time or continuous monitoring in resource-limited settings. Point-of-care electrochemical sensors have shown promise for rapid cTnI detection, but their reliance on antibodies as biorecognition elements and redox mediator solutions, and single-use operation restricts practical translation. Here, we report an ultrasound-enabled refreshable electrochemical biosensor for sensitive, stable, and repeatable cTnI monitoring. The device employs a cTnI-specific peptide as the biorecognition element, providing enhanced stability during storage, transport, and operation. Label-free electrochemical impedance spectroscopy quantifies impedance changes upon cTnI binding in body fluids, including serum and saliva, enabling rapid analysis and high sensitivity with electroosmotic enhancement. The sensor achieves a wide dynamic range from 0.031 pg/mL to 1.5 ng/mL for cTnI detection and quantification in 15 min. Compared to previously reported electrochemical platforms and conventional laboratory-based high-sensitivity assays, the proposed sensor offers improved analytical performance, as defined by limit of detection, dynamic range, and assay time. Importantly, low-power ultrasound effectively refreshes the sensor by removing bound targets without damaging the peptide, enabling sustained measurements and prolonging sensor lifetime. The demonstrated sensitivity enhancement and refreshability establish a foundation for extending this approach to diverse biomarkers, paving the way for frequent molecular monitoring and early clinical intervention.