An Universal packaging technique for low-drift implantable pressure sensors

Area of Science:

• Biomedical Engineering
• Materials Science
• Sensor Technology

Background:

• Long-term bodily pressure monitoring offers vital diagnostic insights.
• Implantable sensors are ideal for continuous measurement, especially in challenging applications like intracranial pressure monitoring.
• Sensor drift has historically hindered the clinical use of implantable pressure sensors.

Purpose of the Study:

• To introduce and validate a universal packaging method to mitigate sensor drift in implantable pressure sensors.
• To enhance the stability and reliability of pressure sensors for long-term biomedical applications.

Main Methods:

• Developed a packaging technique encasing micromachined piezoresistive pressure sensors in a silicone-filled, medical-grade polyurethane balloon.
• Conducted 100-day in-vitro soak tests comparing packaged sensors against a reference transducer.
• Performed in-vivo implantation studies in Ossabow pigs to assess packaging robustness and drift reduction.

Main Results:

• Packaged sensors exhibited stable operation, with output deviations within 1.8 cmH2O (1.3 mmHg) of a reference transducer over 100 days.
• Non-isolated sensors showed significant fluctuations (10-20 cmH2O or 7.4-14.7 mmHg) under identical conditions.
• In-vivo tests confirmed the package's robustness and its effectiveness in reducing baseline drift.

Conclusions:

• The proposed universal packaging technique effectively minimizes sensor drift by isolating the sensor from the aqueous environment.
• This method significantly improves the stability and reliability of implantable pressure sensors, paving the way for advanced medical monitoring.
• The technique demonstrates potential for widespread application in long-term implantable sensing systems.