Peripheral arterial disease (PAD) is a disorder that restricts the blood flow in arteries that carry blood to the limbs; it frequently affects the legs. This restriction occurs due to severe atherosclerosis (stenosis), an accumulation of fatty materials in the vessel lumen. Stents are used to manage this disease. However, in-stent restenosis can occur at an unpredictable time, leading to emergency hospitalization or death.

The wireless magnetoelastic monitoring system showed its potential to detect restenosis. The main components of this system are a miniaturized wireless sensor integrated into the stent and a bias magnet. The purpose of using a magnet is to provide a uniform magnetic field for the sensor to operate. This work aims to improve the design of the system components to be compatible with the commercial self-expanding vascular stents. The magnetoelastic sensor was designed to fit with a conventional self-expanding stent (e.g., Innova™ from Boston Scientific Corp.) used to treat superficial femoral artery lesions. It is designed to be a single layer of MetglasTM 2826MB (12 mm x 0.85 mm x 29 um). However, the sensor could be damaged during the stent deployment. As a result, it is necessary to encapsulate the sensor. A polymeric package was designed to house the sensor and the biasing magnet. The package is attached to the stent structure by two helical wires made of nitinol material. The biasing magnet is a strip of ArnokromeTM 5 (13.2 mm x 0.85 mm x 50 um). FEA tool was used to evaluate the performance of the sensor and the magnetic strip. The results showed that the sensor vibrates at 149 kHz. The magnetic field distribution confirmed that the ArnokromeTM 5 generates a sufficient magnetic field strength for the sensor to operate. This work also covers an analytical analysis of using electromagnetic coils to provide DC bias for the system. However, the results showed that the heat dissipated from the coils could be hard to manage.

If implanting this package is successful in vivo experiments, the detection of restenosis will be achieved in an earlier stage, saving the patient from undergoing another surgery. Therefore, the wireless monitoring system can reduce emergency surgeries and mortality that results from PAD, leading to healthier patients and a lower burden on hospital resources.

Date: Tuesday, August 10, 2021
Time: 1:00 PM
Zoom: https://umich.zoom.us/j/99281419966
Chair: Prof. Yogesh B. Gianchandani