Related Experiment Video
Updated: Aug 30, 2025
08:53
Label-free Single Molecule Detection Using Microtoroid Optical Resonators
Published on: December 29, 2015
9.3K
Part-per-Trillion Trace Selective Gas Detection Using Frequency Locked Whispering-Gallery Mode Microtoroids
Cheng Li1, Trevor Lohrey2, Phuong-Diem Nguyen3
1Wyant College of Optical Sciences, The University of Arizona, 1630 E University Blvd, Tucson, Arizona85721, United States.
ACS Applied Materials & Interfaces
|September 1, 2022
Summary
Highly sensitive whispering-gallery mode (WGM) microresonator sensors were developed for selective detection of toxic gases like DIMP, formaldehyde, and ammonia at trace levels. These polymer-coated sensors offer improved selectivity and rapid detection for industrial and safety applications.
Area of Science:
- Optoelectronics and Photonics
- Chemical Sensing and Spectroscopy
- Materials Science and Engineering
Background:
- Rapid detection of toxic gases is crucial for industrial safety, defense, and laboratory environments.
- Whispering-gallery mode (WGM) microresonators offer high sensitivity due to long photon confinement.
- A key challenge for WGM sensors is achieving high selectivity for specific target analytes.
Purpose of the Study:
- To develop highly selective and sensitive WGM microresonator sensors for toxic industrial chemicals and chemical warfare agent surrogates.
- To investigate the use of various polymer coatings for selective gas detection.
- To enable rapid, multi-agent detection capabilities using a single sensor platform.
Main Methods:
- Frequency-locked WGM microtoroid optical resonators were covalently modified with specific polymer coatings.
- Polyethylene glycol (PEG) was used for diisopropyl methylphosphonate (DIMP) detection.
- A novel one-pot synthesis of 3-(triethoxysilyl) propyl-terminated polyvinyl acetate (PVAc) was developed for ammonia sensing, followed by alkaline hydrolysis to polyvinyl alcohol (PVA) for formaldehyde detection.
Main Results:
- Selective detection of DIMP, formaldehyde, and ammonia at parts-per-trillion (ppt) concentrations (304, 434, and 117 ppt, respectively) was achieved.
- The achieved detection levels are 1-2 orders of magnitude better than previously reported for similar systems, excluding vacuum-based pristine graphene/carbon nanotube sensors.
- Microtoroids coated with a polymer mixture demonstrated the ability to detect multiple agents simultaneously.
Conclusions:
- Polymer-coated WGM microtoroids provide a highly sensitive and selective platform for detecting toxic industrial chemicals and chemical warfare agent surrogates.
- The developed polymer functionalization strategies and synthesis methods enable reliable and reproducible sensor fabrication.
- This technology holds significant promise for advancing rapid early detection systems for hazardous chemical agents.
