3D printing of electrochemical detectors

• Main Author: Ng, Candy
• Other Authors: Chen Zhong
• Format: Final Year Project
• Language: English
• Published: 2017
• Subjects: DRNTU::Engineering::Materials
• Online Access: http://hdl.handle.net/10356/72151
• Institution: Nanyang Technological University

Electrochemical (EC) detection is a powerful tool supporting simple, low cost and rapid analysis. Anodic Stripping Voltammetry (ASV) is one of the EC detection method that can trace heavy metals at ppb levels with low cost, simple sample preparation and portability. However, most of the existing works are focused on the development of working electrode materials and the only way to fabricate disposable EC detectors is screen printing technique. Thus, it aroused our great interest to use 3D printing technique to pattern and fabricate the EC detectors with more flexibility. Prior to fabricating the electrodes, the printing bed was calibrated, the paste was filled in the syringe, and G-code for printing was modified. The electrodes were first printed with silver/silver chloride paste, followed by carbon paste printing, then cured at 70°C for 1 hour. After that, a layer of insulation materials was applied on the top of the conducting wires of the electrodes. Various problems, such as tube bulging, incompatible printing mechanism and accumulation of paste at the syringe tip were solved in electrode printing by selecting suitable tools and modifying the G-code. Repeated cyclic voltammetry (CV) tests on the printed EC electrodes with potassium ferrocyanide in sodium chloride solution indicated good reversibility of the electrodes in redox reactions. The EC electrodes demonstrated successful ASV detection of standard Pb(II) and Cd(II) solutions at the concentrations of 50 to 1000 ppb in 0.1M acetate buffer, at a decent linear characterization curve with R2 of 0.99. However, some variations in the electrode performance were observed probably due to the inconsistent thickness and surface roughness of the electrodes. The limit of detection (LOD) for both Pb and Cd was 50 ppb. The high LOD could be caused by impurities in electrolyte and reaction on the electrode itself. Furthermore, tap water spiked with Pb(II) and Cd(II) was measured with ASV, which showed that the 3D printed electrodes can detect the heavy metals in real-life sample. All the results indicate that 3D printing technique is a feasible alternative to screen printing technique. Future work should be focused on improving the consistency of 3D printed product and user friendliness of this technique.