Chlorine is used as a powerful disinfectant in water-related industries and in the food industry to
remove bacteria and other harmful contaminants. We present a solution-based fabrication
process for a biodegradable electrochemical free chlorine sensor using asparagine that is
functionalized onto graphene oxide (GO). An ink solution of the GO functionalized with
asparagine was fabricated then deposited onto a screen-printed carbon electrode (SPCE) using a
spin-coater. The sensor showed high a sensitivity of 0.30 μA ppm−1 over a linear range of 0 to 8
ppm with a hysteresis-limited resolution of 0.2 ppm, very high selectivity in the presence of
commonly interfering ions, and an operating voltage well below the reduction potential of
dissolved oxygen. The sensor response time to achieve a steady state was 50 s, and it showed
little change in its drift response over 16 h and over a temperature range of 10 to 45 °C. From the
development of the free chlorine sensor, over 9000 datapoints were collected and used for
training a neural network model to quantify and characterize factors affecting the free chlorine
sensor performance. A readout system was designed with a printed circuit board and an android
app to simplify free chlorine sensing for an end user. / Thesis / Master of Applied Science (MASc) / Free chlorine is used to disinfectant sources of water, and eliminate pathogens. The World
Health Organization (WHO) maintains strict amounts of free chlorine in water due to its
widespread usage owed to its low cost and persistence in water systems. Too little, and it will not
be an effective disinfectant, and too much and the high consumption of free chlorine increases
the risk cancer or the formation of hazardous chemicals. Recently, free chlorine sensors that
measure an electrical response proportional to the amount of free chlorine are gaining interest for
fast, accurate, and repeatable measurements.
This thesis focuses on the design, fabrication, and evaluation of these sensors made using
biodegradable materials in a solution-based fabrication processes with the aim of working
towards large-scale fabrication of a printable ink. First, we review the results achieved by the
sensors within recent literature. Second, we present the design of a sensor that aims to achieve
environmentally friendly goals and maintain competitive performance characteristics. The, the
sensor is tested under various conditions with its performance quantified under different
conditions. Third, the sensor is characterized using a neural network to measure its performance
and identify sources of improvement for future designs. Finally, we incorporate the sensor with
an android app to measure free chlorine in remote water systems.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/28241 |
| Date | January 2022 |
| Creators | Siddiqui, Junaid |
| Contributors | Deen, Jamal, Electrical and Computer Engineering |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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