Silicon-based optoelectronic integrated circuit for label-free bio/chemical sensor.

Area of Science:

• Optoelectronics
• Integrated Photonics
• Biosensing

Background:

• Label-free biosensing is crucial for real-time diagnostics.
• Existing methods often require complex instrumentation or labels.
• Silicon photonics offers a scalable platform for integrated sensing.

Purpose of the Study:

• To develop a silicon-based optoelectronic integrated circuit (OEIC) for label-free bio/chemical sensing.
• To demonstrate a novel sensing mechanism utilizing a tunable microring and electrical readout.
• To evaluate the system's performance for both bulk and surface sensing applications.

Main Methods:

• Fabrication of a silicon OEIC comprising grating couplers, a tunable microring filter, a sensing microring, and a Ge photodetector.
• Utilizing a broadband ASE light source and on-chip tunable filter for sliced light generation.
• Employing electrical power scanning on a tracing microring to detect refractive index changes.
• Direct electrical readout of sensing signals via the Ge photodetector.

Main Results:

• Demonstrated bulk refractive index sensing with a sensitivity of ~15 mW/RIU and a detection limit of 3.9 μ-RIU.
• Achieved surface sensing of biotin-streptavidin with a surface mass sensitivity of ~192 µW/ng·mm(-2) and a detection limit of 0.3 pg/mm(2).
• The OEIC system provides a direct electrical readout without wavelength scanning.

Conclusions:

• The developed silicon OEIC enables sensitive and label-free bio/chemical detection.
• The system's high sensitivity and direct electrical readout are advantageous for diagnostic applications.
• This integrated photonic sensing platform is well-suited for point-of-care applications.