Toward Synthetic Vascular Graft Monitoring Using a Flip-Chip-on-Flex Impedance Spectroscopy Sensor

Synthetic vascular grafts are used in a wide range of clinical applications. However, they can become prone to occlusion over time, due to the growth of vascular smooth muscle cells (VSMCs). This phenomenon is associated with graft failure. Here, we describe novel techniques for packaging and integration of a miniature sensor of VSMC growth. The sensor was based on a microfabricated array of interdigitated platinum electrodes on a silicon substrate. It was assembled using flip-chip-on-flex (FCOF) technology to create a low-profile package that can be manufactured using industry-standard tools and is suitable for integration with a synthetic vascular graft. The packaged sensor responded to changes in solution impedance and accurately detected the growth of VSMC in vitro. We also demonstrated successful proof-of-concept integration of the sensor with a custom synthetic graft. Together these technologies have the potential to allow early detection of VSMC growth prior to graft occlusion, enabling more timely and effective clinical interventions to be made.