Active Opto-Magnetic Biosensing with Silicon Microring Resonators

Area of Science:

• Integrated optical biosensors
• Lab-on-chip platforms
• Biosensing technologies

Background:

• Standard optical biosensing relies on measuring optical shifts during lengthy hybridization.
• External perturbations during measurement can lead to inaccurate results and invalid tests.
• Current methods require continuous monitoring over hours, increasing susceptibility to environmental factors.

Purpose of the Study:

• Introduce a novel Opto-Magnetic biosensing assay concept.
• Enable off-line, rapid optical measurement of biomolecular recognition.
• Improve the reliability and efficiency of biosensing for lab-on-chip systems.

Main Methods:

• Utilized microring resonators to detect changes in effective refractive index.
• Immobilized magnetic nanoparticles as labels for target molecules.
• Applied an external AC magnetic field to oscillate bound nanoparticles.
• Employed a lock-in technique to record microring transfer function modulation.

Main Results:

• Achieved a lowest detected concentration of 10 picomolar (pM) for a DNA model system.
• Demonstrated an effective refractive index variation limit of detection of 7.5×10-9 refractive index units (RIU).
• Completed measurements in a significantly reduced time frame of a few seconds.

Conclusions:

• Opto-Magnetic biosensing provides a robust alternative to conventional optical biosensing.
• The method allows for off-line, rapid, and highly sensitive detection of biomolecular interactions.
• This technique holds promise for advancing lab-on-chip diagnostics and real-time monitoring.