The Fabrication of Paper-based Multi-walled Carbon Nanotubes Electrode Sensors Using Inkjet Printer

Paper-based electrode sensors are low-cost, biodegradable and easy to fabricate, and are usually developed for single-use detection, to avoid cleaning and cross-contamination. Nanomaterials have gained wide interest as key components for paper-based electrode sensors, as they can be easily deposited onto paper substrates. The aim of this research is to prepare a water-based multi-walled carbon nanotubes (MWCNTs) ink for paper-based electrode sensor fabrication using a home inkjet printer (Canon PIXMA TS205). Different MWCNTs ink formulations were studied to identify the most compatible inks for inkjet printing. Pristine multi-walled carbon nanotubes functionalised with a carboxylic acid group mixed with sodium dodecyl sulphate provided the optimum homogeneity with high electrical conductivity and compatibility with the inkjet printer. This formulation was used to fabricate the MWCNTs-based electrode sensor on Whatman filter paper. However, one of the major challenges with paper-based sensors is water absorption by the paper substrate, making it inappropriate for multiple uses. Three types of coating, perflourocyclobutane (PFC), acrylic acid (AA) and allylamine (AAm), were plasma polymerised onto the paper substrate to enhance the paper substrate stability and electrode sensor performance. The purpose of using PFC is to make the paper substrate surface hydrophobic, to prevent water absorption that may degrade the electrode sensor, while AA and AAm are plasma polymerised to induce hydrophilicity to the surface of PFC-coated filter paper for MWCNTs printing and electrode sensor fabrication. The success of the plasma polymerisation technique and improved performance of the sensor was confirmed using a range of analytical techniques. This PhD project foreshadows the future development of paper-based sensors with high durability and enhanced performance