Wireless, battery-free self-detecting smart arteriovenous graft for stenosis diagnosis in dialysis patients

The development of wireless implantable devices opens opportunities for continuous monitoring of arteriovenous grafts (AVGs) in dialysis patients, who face high risks of graft failure and morbidity due to stenosis. Current methods for graft monitoring rely heavily on intermittent hospital-based tests and skilled personnel. Here, we report a battery-free implantable AVG with a wireless pressure sensor embedded for real-time stenosis detection. The graft incorporates a soft, flexible circuit, enabling external resonant frequency transmission. The capacitive pressure sensor demonstrates high sensitivity and the ability to detect both arterial and venous stenosis. Stretchable conductive inks enhance the resilience of the inductor under mechanical stress, while laser micromachining manufactures flexible, serpentine patterns in the graft's elastomeric layer. Additionally, the thin sensor profile maintains graft flexibility and can integrate with the expanded polytetrafluoroethylene, bringing it closer to commercial AVG functionality. Using a phantom flow model, the bioelectronic system successfully detects both arterial and venous stenoses wirelessly via inductive coupling. Overall, this class of sensor technologies and wireless electronics presented in this work provides an effective solution for real-time dialysis access monitoring, with the potential to significantly reduce AVG failure rates and improve patient outcomes through early intervention.