Functional demonstration of a compact silicon diffractive sensor for toluene.

Area of Science:

• Photonics and Sensor Technology
• Materials Science and Engineering

Background:

• Developing compact and integrated sensors for chemical detection is crucial for point-of-care diagnostics and environmental monitoring.
• Existing spectral-based sensors often require complex optical setups, limiting their field deployability.

Purpose of the Study:

• To demonstrate a compact silicon diffractive sensor for detecting toluene in solution.
• To showcase the sensor's capability for integration into lab-on-a-chip systems.

Main Methods:

• Fabrication of a silicon-on-insulator diffractive sensor utilizing in-plane diffraction gratings.
• Operation at a standard telecommunications wavelength (1550 nm).
• Intensity-based detection of relative diffracted and transmitted light intensities.

Main Results:

• Achieved micrometer-scale device dimensions.
• Demonstrated robust detection independent of signal attenuation.
• Successfully measured toluene concentrations as low as 100 parts per million (refractive index change of 3×10⁻⁴).
• Developed a linear sensor array with individual sensor addressability and 2-D array capability.

Conclusions:

• The silicon diffractive sensor offers a compact, integrable, and robust platform for chemical sensing.
• The demonstrated sensor array capabilities are promising for field-deployable lab-on-a-chip applications.
• This technology enables sensitive detection of analytes in solution via simple intensity measurements.