Next Article in Journal
Design of Miniaturized Dual-Band Microstrip Antenna for WLAN Application
Next Article in Special Issue
Identification of Water Bodies in a Landsat 8 OLI Image Using a J48 Decision Tree
Previous Article in Journal
Time and Energy Efficient Relay Transmission for Multi-Hop Wireless Sensor Networks
Previous Article in Special Issue
Comparison of Metal-Backed Free-Space and Open-Ended Coaxial Probe Techniques for the Dielectric Characterization of Aeronautical Composites
Open AccessArticle

A Flexible Optical pH Sensor Based on Polysulfone Membranes Coated with pH-Responsive Polyaniline Nanofibers

1
Department of Chemical and Process Engineering Technology, Jubail Industrial College, Jubail Industrial City 31961, Saudi Arabia
2
Department of Chemistry, College of Science, University of Hafr Al Batin, Hafr Al Batin 31991, Saudi Arabia
*
Author to whom correspondence should be addressed.
Academic Editor: Francesco Ciucci
Sensors 2016, 16(7), 986; https://doi.org/10.3390/s16070986
Received: 9 March 2016 / Revised: 29 May 2016 / Accepted: 14 June 2016 / Published: 27 June 2016
A new optical pH sensor based on polysulfone (PSU) and polyaniline (PANI) was developed. A transparent and flexible PSU membrane was employed as a support. The electrically conductive and pH-responsive PANI was deposited onto the membrane surface by in situ chemical oxidative polymerization (COP). The absorption spectra of the PANI-coated PSU membranes exhibited sensitivity to pH changes in the range of 4–12, which allowed for designing a dual wavelength pH optical sensor. The performance of the membranes was assessed by measuring their response starting from high pH and going down to low pH, and vice versa. It was found that it is necessary to precondition the sensor layers before each measurement due to the slight hysteresis observed during forward and backward pH titrations. PSU membranes with polyaniline coating thicknesses in the range of ≈100–200 nm exhibited fast response times of <4 s, which are attributed to the porous, rough and nanofibrillar morphology of the polyaniline coating. The fabricated pH sensor was characterized by a sigmoidal response (R2 = 0.997) which allows for pH determination over a wide dynamic range. All membranes were stable for a period of more than six months when stored in 1 M HCl solution. The reproducibility of the fabricated optical pH sensors was found to be <0.02 absorption units after one month storage in 1 M HCl solution. The performance of the optical pH sensor was tested and the obtained pH values were compared with the results obtained using a pH meter device. View Full-Text
Keywords: optical pH sensor membrane; flexible pH sensor; polysulfone; polyaniline; chemical oxidative polymerization; nanofibers optical pH sensor membrane; flexible pH sensor; polysulfone; polyaniline; chemical oxidative polymerization; nanofibers
Show Figures

Figure 1

MDPI and ACS Style

Abu-Thabit, N.; Umar, Y.; Ratemi, E.; Ahmad, A.; Ahmad Abuilaiwi, F. A Flexible Optical pH Sensor Based on Polysulfone Membranes Coated with pH-Responsive Polyaniline Nanofibers. Sensors 2016, 16, 986.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop