A SU-8-based compact implantable wireless pressure sensor for intraocular pressure sensing application.

Area of Science:

• Biomedical Engineering
• Microsystems and Nanotechnology
• Sensor Technology

Background:

• Telemetric sensing offers noncontact methods for human disease detection.
• Accurate intraocular pressure (IOP) monitoring is crucial for diagnosing and managing glaucoma.
• Existing IOP monitoring methods may be invasive or lack remote sensing capabilities.

Purpose of the Study:

• To develop a compact, passive wireless pressure sensor for measuring intraocular pressure.
• To utilize SU-8 based microfabrication for a biocompatible and isolated sensor design.
• To achieve high sensitivity and remote detection of IOP changes.

Main Methods:

• Microfabrication of a SU-8 based passive LC parallel circuit sensor using gold and SU-8.
• Design of a pressure-sensitive diaphragm integrated with the LC circuit.
• Characterization of sensor performance in air and saline environments for pressure sensitivity.
• Utilizing an external readout coil for wireless signal detection up to 6 mm distance.

Main Results:

• A compact passive wireless pressure sensor (1.52 mm × 3.23 mm × 0.2 mm) was successfully fabricated.
• The SU-8 encapsulation effectively isolated the internal circuitry from the biological medium.
• The sensor demonstrated high pressure sensitivity exceeding 7,000 ppm/mmHg.
• Wireless signal detection was achieved at a distance of up to 6 mm.

Conclusions:

• The developed SU-8 based sensor is a promising candidate for noncontact, wireless intraocular pressure monitoring.
• The sensor's high sensitivity and biocompatible design facilitate remote detection of IOP.
• This technology advances telemetric sensing for ophthalmic disease management.