• 1 Department of Electrical, Electronic and System Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia (UKM), Bangi 43600, Malaysia
  • 2 Department of Computer System and Technology, Faculty of Computer Science and IT, University of Malaya, Kuala Lumpur 50603, Malaysia
  • 3 Faculty of Engineering Technology, Universiti Teknikal Malaysia Melaka, Melaka 76100, Malaysia
  • 4 Department of Physics, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia
  • 5 Institute of Microengineering and Nanoelectronics, Universiti Kebangsaan Malaysia (UKM), Bangi 43600, Malaysia
  • 6 Department of Optoelectronic Engineering, Jinan University, Road Huangpu, District Tianhe, Guangzhou 510632, China
Sensors (Basel), 2021 Oct 27;21(21).
PMID: 34770442 DOI: 10.3390/s21217132


Tungsten disulphide (WS2) is a two-dimensional transition-metal dichalcogenide material that can be used to improve the sensitivity of a variety of sensing applications. This study investigated the effect of WS2 coating on tapered region microfiber (MF) for relative humidity (RH) sensing applications. The flame brushing technique was used to taper the standard single-mode fiber (SMF) into three different waist diameter sizes of MF 2, 5, and 10 µm, respectively. The MFs were then coated with WS2 via a facile deposition method called the drop-casting technique. Since the MF had a strong evanescent field that allowed fast near-field interaction between the guided light and the environment, depositing WS2 onto the tapered region produced high humidity sensor sensitivity. The experiments were repeated three times to measure the average transmitted power, presenting repeatability and sensing stability. Each MF sample size was tested with varying humidity levels. Furthermore, the coated and non-coated MF performances were compared in the RH range of 45-90% RH at room temperature. It was found that the WS2 coating on 2 µm MF had a high sensitivity of 0.0861 dB/% RH with linearity over 99%. Thus, MF coated with WS2 encourages enhancement in the evanescent field effect in optical fiber humidity sensor applications.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.