Abstract
Stent implantation is widely used to treat coronary artery disease, yet in-stent restenosis (ISR) remains a major clinical challenge. Fractional flow reserve (FFR) is the gold-standard index for evaluating restenosis severity, but current techniques are invasive and unsuitable for continuous monitoring. Here, we present a bioresorbable smart stent platform that enables real-time intravascular pressure sensing and continuous FFR monitoring. The system integrates a MEMS-based LC pressure sensor, fabricated from SU-8 and gold, onto a hybrid 3D-printed vascular stent composed of polycaprolactone (PCL) and polylactic acid (PLA). Structural refinements and an optimized fabrication process enable long-term sensor reliability, minimize signal drift, and maintain stable resonance frequency. Across 100 fabricated devices, the pressure sensors show a resonance frequency of 82.2 ± 1.7 MHz and a sensitivity of 37.48 ± 2.13 kHz/mmHg. In vitro closed-loop fluidic tests using a vascular phantom confirmed the stable, wireless operation of the device and its ability to accurately assess hemodynamic parameters. The dual-sensor configuration enables simultaneous upstream and downstream pressure measurements, yielding FFR values that closely match those from a commercial system (R² = 0.97) under varying stenosis severities. The proposed smart stent offers a promising pathway toward long-term, non-invasive vascular monitoring and early detection of ISR.