Encapsulation Approaches for In-Stent Wireless Magnetoelastic Sensors

Area of Science:

• Biomedical Engineering
• Materials Science
• Sensor Technology

Background:

• Wireless magnetoelastic sensors show promise for detecting biomass accumulation in stents, crucial for preventing occlusion.
• Effective encapsulation is vital for sensor function during implantation and long-term deployment within curved biological environments.

Purpose of the Study:

• To evaluate two polymer-based encapsulation designs (flexible Type F and stiff Type S) for ribbon-like magnetoelastic sensors within plastic biliary stents.
• To assess the mechanical performance and signal integrity of encapsulated sensors under conditions simulating implantation and deployment.

Main Methods:

• Two polymer package designs (Type F and Type S) were created for 12.5 mm x 1 mm x 60 μm magnetoelastic sensors within 2.54 mm inner diameter biliary stents.
• Mechanical tests evaluated sensor protection during delivery and accommodation of bending to a 3 cm radius of curvature.
• In-situ testing of the Type F package was performed in a porcine bile duct model.

Main Results:

• Both Type F and Type S packages protected sensors from introducer forces and allowed bending.
• Type F offered flexibility for delivery, while Type S maintained signal strength in curved conditions.
• In-situ tests showed measurable signals from the Type F package at a 10 cm wireless range, 159 kHz resonant frequency, and 397 quality factor.

Conclusions:

• Both flexible and stiff encapsulation designs are viable for protecting magnetoelastic sensors within biliary stents.
• The choice of encapsulation impacts delivery flexibility and signal maintenance in curved anatomy.
• Further in-situ validation supports the potential of these encapsulated sensors for in-vivo biomass monitoring.