A Wireless Pressure Sensor Integrated with a Biodegradable Polymer Stent for Biomedical Applications

Area of Science:

• Biomedical Engineering
• Materials Science
• Microsystems Engineering

Background:

• Smart stents require integrated sensors for real-time monitoring of physiological parameters.
• Accurate intravascular pressure measurement is crucial for assessing stent performance and cardiovascular health.
• Existing pressure sensing technologies often require invasive wiring or internal power sources.

Purpose of the Study:

• To develop and characterize a novel wireless, self-powered pressure sensor for integration into smart stents.
• To evaluate the sensor's performance in measuring intravascular pressure within a clinically relevant range.
• To assess the biocompatibility and long-term stability of the sensor within a cardiovascular environment.

Main Methods:

• Fabrication of a micromachined wireless pressure sensor using photosensitive SU-8 polymer.
• Integration of a resonant circuit enabling passive wireless operation.
• Characterization of pressure-induced capacitance variations and resonance frequency shifts.
• Evaluation of sensor performance (0-230 mmHg range, 0.043 MHz/mmHg sensitivity).
• Biocompatibility testing using neonatal rat ventricular myocytes.
• In vivo implantation in animal cardiovascular vessels with subsequent monitoring.
• Fabrication and testing of a 3D-printed biodegradable polycaprolactone stent with the sensor.

Main Results:

• The wireless pressure sensor successfully measured pressure variations from 0 to 230 mmHg with a sensitivity of 0.043 MHz/mmHg.
• The sensor demonstrated no adverse effects on cardiac cells, indicating good biocompatibility.
• In vivo studies showed no abnormalities in animal blood vessels for approximately one month post-implantation.
• A 3D-printed biodegradable polymer stent integrated with the sensor exhibited improved sensitivity compared to a metal stent.

Conclusions:

• A novel wireless pressure sensor suitable for smart stent applications has been successfully fabricated and characterized.
• The sensor operates without an internal power source, offering a significant advantage for minimally invasive medical devices.
• The wireless pressure sensor exhibits promising biocompatibility and stable performance in both in vitro and in vivo settings.
• Biodegradable polymer stents show potential for enhanced performance when integrated with this wireless sensing technology.