DNT detection using microspheres coated with NaYF4-Yb3+,Er3+-nanocrystals functionalized with PAA/PAH layers

Abhishek Kottaram Amrithanath, Heming Wei, Sridhar Krishnaswamy

Research output: Chapter in Book/Report/Conference proceedingConference contribution


In this paper, we demonstrate the fabrication of a chemical sensor for 2,4-dinitrotoluene (DNT), based on an opticalfiber- microsphere coated with upconversion nanocrystals functionalized with layers of polyelectrolytes - poly(acrylic acid) (PAA) and poly(allylamine hydrochloride) (PAH). The design consists of a microsphere, which supports whispering-gallery-modes (WGM), coupled to an optical fiber. The NaYF4-Yb3+,Er3+ nanocrystals have a bright fluorescence around 550 nm and 650 nm when irradiated with 980 nm, which is enhanced by the WGM. When functionalized with PAA/PAH layers, these nanocrystals can be coated on the microsphere with control over layer thickness. The presence of DNT on the surface of the microsphere quenches the fluorescence as the absorption spectrum of DNT has peaks in 500 - 600 nm. The effect of concentration of the analyte on the magnitude of quenching has been studied. The paper discusses the design, fabrication and characterization of the chemical sensor.

Original languageEnglish (US)
Title of host publicationNano-, Bio-, Info-Tech Sensors, and 3D Systems II
EditorsVijay K. Varadan
ISBN (Electronic)9781510616905
StatePublished - 2018
EventNano-, Bio-, Info-Tech Sensors, and 3D Systems II 2018 - Denver, United States
Duration: Mar 5 2018Mar 7 2018

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


OtherNano-, Bio-, Info-Tech Sensors, and 3D Systems II 2018
CountryUnited States


  • DNT
  • Microsphere
  • erbium
  • polyelectrolyte
  • upconversion
  • upconversion nanoparticles
  • whispering gallery mode

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

Fingerprint Dive into the research topics of 'DNT detection using microspheres coated with NaYF<sub>4</sub>-Yb<sup>3+</sup>,Er<sup>3+</sup>-nanocrystals functionalized with PAA/PAH layers'. Together they form a unique fingerprint.

Cite this