A Solidly Mounted Resonator Based on c-Axis-Tilted Scandium-Doped Aluminum Nitride Films for Cardiac Troponin I Detection

Cardiovascular diseases remain a leading cause of death worldwide, with acute myocardial infarction (AMI) accounting for a significant proportion of fatalities. The rapid and accurate detection of cardiac troponin I (cTnI) is critical for early diagnosis of AMI. We report an innovative, highly sensitive, solidly mounted resonator (SMR) biosensor based on a c-axis-tilted scandium-doped aluminum nitride (Sc_0.1Al_0.9N) film for label-free cTnI detection. The SMR device, fabricated by magnetron sputtering and incorporating an acoustic Bragg reflector, is designed to operate in the shear acoustic mode. The sensor demonstrates a quality factor of 2030 and an effective electromechanical coupling coefficient of 2.6%. Functionalized with a self-assembled monolayer and monoclonal antibodies, the sensor achieves a detection limit of 3 pg/mL for cTnI in serum, with a rapid response time of 100 s and high selectivity against common interferents. The device also exhibits significant potential for integration with CMOS electronics, supporting the development of miniaturized, point-of-care (POC) diagnostic systems for cardiovascular diseases.