Fabrication of a miniature CMOS-based optical biosensor

Area of Science:

• Biomedical Engineering
• Biosensor Technology
• Optoelectronics

Background:

• Miniaturized biosensors are crucial for point-of-care diagnostics.
• Existing biosensors often require larger sample volumes and longer detection times.
• Integration of enzymes with semiconductor technology offers new sensing possibilities.

Purpose of the Study:

• To develop a novel, miniature optical biosensor utilizing a CMOS photosensing chip.
• To immobilize horseradish peroxidase (HRP) and/or glucose oxidase (GOx) enzymes for H2O2 and glucose detection.
• To characterize the performance of the developed optical biosensors.

Main Methods:

• Immobilization of HRP or HRP/GOx enzyme pair on a 0.5 mm x 0.5 mm CMOS photosensing chip using TEOS/PDMS Ormosil.
• Real-time detection of HRP-catalyzed luminol luminescence for H2O2 and glucose.
• Optimization of operating temperature, pH, and assessment of dynamic range and interference.

Main Results:

• The optical biosensors achieved real-time detection of H2O2 and glucose with a minimum reaction volume of 10 µL.
• Optimal performance was observed at 20-25°C and pH 8.4.
• Linear dynamic ranges were 0.05-20 mM for H2O2 and 0.5-20 mM for glucose, with good reproducibility (RSD 4.3%) and minimal interference from ascorbic and uric acid.

Conclusions:

• The developed CMOS-photodiode-based optical biosensors offer advantages including short detection times and small sample volumes.
• High reproducibility and a wide dynamic range were demonstrated.
• This technology presents a promising platform for sensitive and efficient biosensing applications.