High-sensitivity optical biosensor based on cascaded Mach-Zehnder interferometer and ring resonator using Vernier...

Area of Science:

• Photonics
• Biosensing
• Nanotechnology

Background:

• Accurate and sensitive biosensing is crucial for early disease detection and medical diagnostics.
• Existing biosensor technologies face limitations in sensitivity and detection limits.
• Silicon photonics offers a scalable platform for developing high-performance optical sensors.

Purpose of the Study:

• To demonstrate an ultrahigh sensitivity silicon photonic biosensor.
• To leverage the Vernier effect in cascaded Mach-Zehnder interferometers (MZI) and ring resonators for enhanced sensitivity.
• To validate the sensor's performance in a relevant biosensing application.

Main Methods:

• Fabrication of a silicon photonic biosensor integrating cascaded Mach-Zehnder interferometers (MZI) and a ring resonator.
• Utilizing wavelength interrogation for signal detection.
• Demonstrating biosensing by monitoring the interaction between goat and antigoat immunoglobulin G (IgG) pairs.

Main Results:

• Achieved ultrahigh sensitivities of 2870 nm/RIU for the MZI sensor and 21,500 nm/RIU for the MZI-ring sensor.
• Detected a wavelength shift of 0.035 nm for 1 ng/ml IgG using the MZI sensor.
• Detected a wavelength shift of 0.5 nm for 1 ng/ml IgG using the MZI-ring sensor, demonstrating enhanced sensitivity.

Conclusions:

• The cascaded MZI and ring resonator design with the Vernier effect significantly enhances biosensor sensitivity.
• The developed silicon photonic biosensor exhibits excellent performance for detecting low concentrations of biomolecules.
• This high-performance sensor holds significant promise for future medical diagnostic applications.