A Stent Graft Occlusion Detection : Pressure Sensing Implant Device with Inductive Power and Data Telemetry

Transjugular intrahepatic portosystemic shunt (TIPS) procedure has been used for the treatment of portal hypertension induced due to liver cirrhosis. A small metallic tube called stent graft is inserted during TIPS for rerouting blood flow in the liver. Common complications after TIPS is partial or complete blockage inside or at either ends of the stent graft. This paper presents the design and fabrication of a smart stent graft containing two pressure sensors for detecting blockages occuring after TIPS. The active implant device with pressure sensor is powered wirelessly and it transmits measured pressure data wirelessly to the external monitoring station using inductive coupling. Ferrite inductor antennas are used for wireless power reception and PCB trace antenna is used for wireless data transmission in the implant device. A smart stent graft is fabricated by coating PTFE membrane on the bare stent followed by mounting of the implant devices. The in vivo setup is emulated by placing the smart stent graft inside meat and powering the implant device with wireless inductive telemetry link. Test result shows that implant device can be operated for a wireless range of 4.5 cm using 15 W 2.05 MHz RF power sender.