Ureteral stent sleeve for early detection of hydronephrosis

Hydronephrosis, a serious complication of ureteral stents, can lead to deterioration of renal function due to prolonged increased intrarenal pressure. Currently, the only way to diagnose hydronephrosis is radiographic imaging, and a continuous, non-invasive method is not available. This study introduces the ureteral stent sleeve, UroSleeve, a modular wireless pressure monitoring system that is designed to integrate seamlessly with standard ureteral stents without altering their existing designs or manufacturing processes. The UroSleeve incorporates a flexible printed-circuit-board-based spiral antenna and a surface-micromachined capacitive pressure sensor, forming an inductor-capacitor tank circuit capable of wireless telemetry through near-field inductive coupling. The device was evaluated in an ex vivo porcine kidney model whose internal pressure was externally controlled to mimic a hydronephrosis condition, and kidney pressure changes were successfully monitored by detecting shifts in the resonant frequency of the device. Key results demonstrated a high sensitivity with -5.3 ± 0.74 kHz/mmHg with a baseline resonant frequency of 15.234 MHz at 8.5 mmHg. The frequency response showed a strong correlation with kidney pressure, and the device maintained consistent performance in a relevant biological environment. The results indicate that UroSleeve offers a practical and versatile solution for wireless intrarenal pressure monitoring, amenable to future clinical translation.