DEVELOPMENT OF DIRECT-INK WRITER FOR PROTOTYPING PAPER BASED CAPACITIVE SWITCH AND CHARACTERISATIONS

This study presents a comprehensive investigation into the development and application of direct ink writing (DIW) techniques for rapid and cost-effective prototyping of capacitive switches. The research applied direct writing with mini-CNC and extrusion systems to achieve precise control over the carbon ink deposition process, enabling the fabrication of complex sensor geometries with high accuracy. The performance and characteristics of a fabricated capacitive sensor were evaluated using various characterization techniques, including Field Emission-Scanning Electron Microscopy (FE-SEM) for morphological examination, Energy Dispersive X-ray (EDX) for elemental mapping, Xray-diffraction (XRD) for assessing the crystallinity of the carbon composite material, nanoindentation for mechanical property assessment, and current-voltage and capacitance measurements. With 47.4% carbon content, as indicated by the FE-SEM, the printed carbon trace's elastic modulus and electrical conductivity are determined at 3.31±1.3 GPa and range from 100 to 190 S/m, respectively. The physical mixed carbon composite ink remains highly crystalline and robust as indicated by the XRD and EDX results. Nanoindentation suggested the need for a protective liner to avoid plastic deformation, but this altered the log ΔC of the capacitive switch. The printed capacitive switch is responsive to 3 to 4 Hz of tapping. The study demonstrates the application of DIW in printing functional capacitive switches with suitable physical and electrical properties, contributing to the realization of innovative and versatile sensor fabrication solutions.