Piezoelectric biosensor for smart cardiovascular grafts based on NaNbO3 fibers/PDMS structured composite

Abstract

An artificial graft inserted in the vascular system can cause thrombosis, which may lead to catastrophic consequences. New intelligent vascular prosthetics that can recognize the presence of clots are urgently needed. For this purpose, a novel biocompatible piezocomposite is designed for self-monitoring smart vascular grafts. The new insight of this work involves the fabrication of a composite with low filler content (5 %v) and high piezoelectric sensitivity (g33 ∼ 130 mV m N−1) suitable for biosensors. The composite is produced by structuring fibers (NaNbO3 fibers) in elastomeric matrix via dielectrophoresis. The matrix with low elastic modulus offers great stretchability to prevent graft performance deterioration. Numerical simulation together with experimental characterizations confirm the improvements in terms of electric field distribution, dielectric and piezoelectric properties. The new composite, integrated on a graft and placed into a motorized cardiovascular simulator performs successfully online monitoring of the blood pressure, identifying anomalies related to a thrombus. The composite coupled with an inductive coil forms a resonant sensor, whose resonance frequency shifts when an occlusion develops. In the future, this system could be implemented using radio frequency identification tags (RFID-tag) to wirelessly supervise the condition of the graft, paving the way to a next generation of self-monitoring grafts.