A stent-graft endoleakage monitor: Telemetry system based on inductive-coupling transmission for implantable pressure sensors

A direct arterial pressure monitoring system for post EVAR procedure based on inductive-coupling is presented which avoids the need for more complex biomedical imaging systems. Post stent-graft implantation complications, such as endoleaks, can be detected with capacitive pressure sensors placed in the stent-graft and monitored externally after the measurement of the oscillation frequency of a LC resonant circuit created by sensors and inductive coupling. Several measurements were performed in order to characterize the system and compare the results with the expected values based on theoretical models. Different measurements were carried-out with the purpose of evaluating the system´s frequency detection accuracy throughout the working bandwidth and varying distances between the reader and the sensors. Both air and a phantom with electrical characteristics similar to the human body were used between the reader and the sensors antennas in order to evaluate the influence of the transmission medium. It is shown that in both cases the system is capable of detecting the oscillation frequencies, even in the case a cluster of sensors is used.