Characterization of chemical sensor for water quality surveillance

• Main Author: Yuan, Soon
• Other Authors: Miao Jianmin
• Format: Final Year Project
• Language: English
• Published: 2018
• Subjects: DRNTU::Engineering; DRNTU::Engineering::Mechanical engineering::Mechatronics
• Online Access: http://hdl.handle.net/10356/75678
• Institution: Nanyang Technological University

Heavy metal such as cadmium has been an essential material and tool used by industry for daily activities. Long term exposure to cadmium from unintentional consumption contaminated water source can pose tremendous effects on human health which result in kidney, bone and lung diseases. Therefore, continuous monitoring of water quality and quick identifying heavy metal contamination are vital to prevent such issue to worsen. Conventional water quality measurement relies on the process of collecting water samples and transferring the samples to a laboratory for complicated analysis using the conventional centralized testing equipment. However, there are many chances to bring unpredictable errors into the final result since the transportation procedures, as well as the testing sequences, will take quite a long time to accomplish. In recent years, the development of portable, sensitive and miniaturized chemical sensor shows great prospective since the compact chemical sensor can be considered as a potential replacement of conventional centralized testing equipment. Besides, anodic stripping voltammetry technique can be selected for on-site evaluation of heavy metal ions because of its simple operation, high sensitivity, good differentiation, and portability. In addition, conventional mercury electrode that is not appropriate for on-site measurement due to its toxicity can be even substituted by bismuth which is environmentally friendly. A study shows that capability of bismuth to form an alloy with targeted heavy metal ions shortens the pre-concentration process of metal ions on the electrode and hence improves the sensitivity of heavy metal detection. All MEMS-based chemical sensors are further modified by drop-casting the working electrode with different concentration and volume of bismuth nanoparticles. The results of each experiment are presented and compared. Commencing the collected results, the modified MEMS-based chemical sensor by drop-casting the working electrode with 3µL of 50mg/L concentration of bismuth nanoparticles showed the highest peak current as compared to others modified working sensors. With the gratifying result, the proposed modification of MEMS-based chemical sensor with the optimum amount of bismuth nanoparticles allows better testing sensitivity. The modified sensors have a very decent potential to be used for electrochemical applications in on-site heavy metal detection field.