Abstract

We synthesize lipophilic, highly efficient, and pH-insensitive oleic acid-modified quantum dots (QDs) with maximum emission at a wavelength of 628 nm. The pH sensing film is fabricated by encapsulating 5-hexadecanoylamino-fluorescein and QDs as the reference in D4–hydromed and plasticized polystyrene. Using a light-emitting diode with a central wavelength of 410 nm as an excitation source, it is shown that the emission wavelengths of the pH sensitive indicator and reference dye have no spectral overlap and match respectively the channels of a 3CCD (RGB) camera with low cross-talk. A series of validation experiments shows that this ratiometric pH optode has good properties of high sensitivity, long-term stability, and photostability. It had a fast response time of $<20\mathrm{s}$ when going from pH 6.3 to pH 8.0. The pH images suggest that the proposed ratiometric pH-sensing approach has great advantage and promise for field applications.

© 2018 Optical Society of America

Ratiometric optical fiber sensor for dual sensing of copper ion and dissolved oxygen

Cheng-Shane Chu and Chih-Yung Chuang
Appl. Opt. 54(36) 10659-10665 (2015)

Ratiometric optical oxygen sensor based on perovskite quantum dots and Rh110 embedded in an ethyl cellulose matrix

Rispandi Mesin, Cheng-Shane Chu, and Zong-Liang Tseng
Opt. Mater. Express 13(4) 945-955 (2023)

Optical fiber carbon dioxide sensor based on colorimetric change of α-naphtholphthalein and CIS/ZnS quantum dots incorporated with a polymer matrix

Cheng-Shane Chu and Meng-Wei Hsieh
Opt. Mater. Express 9(7) 2937-2945 (2019)

Optical sensor for dual sensing of oxygen and carbon dioxide based on sensing films coated on filter paper

Cheng-Shane Chu and Jhih-Jheng Syu
Appl. Opt. 56(4) 1225-1231 (2017)

High sensitivity detection of different pH ranges with rGO-nanocomposite coated eFBG sensor

Azhar Shadab, Md Tauseef Iqbal Ansari, Sanjeev Kumar Raghuwanshi, and Santosh Kumar
Appl. Opt. 62(19) 5334-5341 (2023)