In-situ synthesis of zeolitic imidazolate framework-8 on an optical microbubble cavity for enhanced ethanol sensing

Area of Science:

• Optical sensing
• Materials science
• Nanotechnology

Background:

• Optical whispering-gallery-mode microcavities offer ultra-sensitive detection.
• Surface treatments improve light-matter interactions and sensing performance.
• Metal-organic frameworks (MOFs) show promise for enhancing sensor capabilities.

Purpose of the Study:

• To functionalize an optical microbubble cavity with zeolitic imidazolate framework-8 (ZIF-8) for ethanol concentration sensing.
• To investigate the sensitivity enhancement achieved by MOF coating.
• To explore the distinct sensing behaviors at different ethanol concentrations.

Main Methods:

• Fabrication of an optical microbubble cavity using heat-and-pull and arc discharge techniques.
• Growth of a multilayer of ZIF-8 on the inner surface of the microcavity.
• Detection of various ethanol solution concentrations using the functionalized microcavity.

Main Results:

• The ZIF-8 functionalized microbubble cavity demonstrated significantly enhanced sensitivity.
• Sensitivity increased by 47 times for concentrations below 0.1% and 7 times for concentrations above 0.1%.
• Distinct sensing behaviors were observed at ethanol concentrations lower and higher than 0.1%.

Conclusions:

• Surface functionalization of optical microcavities with MOFs like ZIF-8 is an effective strategy for boosting sensor sensitivity.
• The microbubble cavity design with an internal microfluidic channel is suitable for trace analyte detection.
• This research provides insights for developing advanced optical sensors with novel materials for superior detection demands.