High-Sensitivity, Quantified, Linear and Mediator-Free Resonator-Based Microwave Biosensor for Glucose Detection

Area of Science:

• Microwave Engineering
• Biosensor Technology
• Biomedical Applications

Background:

• Accurate glucose monitoring is crucial for diabetes management.
• Existing glucose sensing methods often face limitations in sensitivity, linearity, or require mediators.
• Resonator-based microwave biosensors offer label-free detection capabilities.

Purpose of the Study:

• To develop and characterize a high-sensitivity, mediator-free resonator-based microwave biosensor for glucose detection.
• To optimize the biosensor design for enhanced electric field interaction and sensitivity.
• To evaluate the biosensor's performance across various glucose concentrations and temperatures.

Main Methods:

• Fabrication of an asymmetrical differential inductor and inter-digital capacitor on a Gallium Arsenide (GaAs) substrate using advanced micro-fabrication.
• Optimization of the sensor for low-frequency operation to increase electric field penetration.
• Testing the biosensor with glucose solutions ranging from 0.3 to 5 mg/mL at temperatures from 10 to 50 °C.

Main Results:

• Achieved high sensitivity of 117.5 MHz/mgmL⁻¹ with excellent linearity (r=0.9987).
• Demonstrated good amplitude variation of 0.49 dB/mgmL⁻¹ (r=0.9954) and high reproducibility (0.78% at 2 mg/mL).
• Miniaturized biosensor size (0.006λ₀ × 0.005λ₀) with enhanced filling factor due to advanced micro-fabrication.

Conclusions:

• The proposed mediator-free microwave biosensor exhibits superior sensitivity and linearity for glucose sensing.
• The optimized design and micro-fabrication enhance performance metrics, including sensitivity and reproducibility.
• The biosensor is a promising candidate for real-time blood glucose detection measurements.