Rolled-up SiO _x /SiN _x microtubes with an enhanced quality factor for sensitive solvent sensing

Area of Science:

• Nanotechnology
• Optical Sensors
• Materials Science

Background:

• Rolled-up microtubes from strain-engineered nanomembranes offer flexibility and versatility.
• Applications include sensors, batteries, and transistors.
• Whispering-gallery mode (WGM) optical microcavities are crucial for sensitive detection.

Purpose of the Study:

• To develop highly sensitive WGM chemical sensors using rolled-up microtube optical microcavities (RUM-OCs).
• To batch fabricate RUM-OCs using novel PECVD-synthesized SiO x /SiN x bilayer nanomembranes.
• To compare the performance of these new RUM-OCs with conventional designs.

Main Methods:

• Batch fabrication of RUM-OCs via rolling-up of PECVD-synthesized SiO x /SiN x nanomembranes.
• Utilizing the high refractive index of SiN x for enhanced optical properties.
• Characterizing RUM-OCs for quality factor and limit of detection in WGM solvent sensing.

Main Results:

• Achieved an enhanced quality factor of 880 for RUM-OCs, significantly higher than the 50 for SiO/SiO 2 based RUM-OCs.
• Demonstrated a limit of detection of 10 -4 refractive index unit (RIU) for WGM solvent sensing.
• The new RUM-OCs showed a 10-fold improvement in sensitivity compared to conventional SiO/SiO 2 RUM-OCs.

Conclusions:

• PECVD-synthesized SiO x /SiN x nanomembranes enable batch fabrication of high-performance RUM-OCs.
• The developed RUM-OCs exhibit superior optical properties and enhanced sensitivity for chemical sensing.
• This technology advances the development of next-generation WGM chemical sensors.