Electrical characterisation of multi-walled carbon nanotube/polydimethylsiloxane using improved facile dispersion technique

Abstract

The growth of polymer composite in technological advancement has contributed to the development of electrocardiogram (ECG) electrode, which gives better wearable conformality on human skin. This gives a promising alternative to Multi-Walled Carbon Nanotube (MWCNT) and polydimethylsiloxane (PDMS) due to its low cost, ease of manufacturing and flexibility. However, with the high aspect ratio and strong Van der Waals interaction forces, MWCNT easily agglomerates, and bundling to each other. An effective dispersion technique of MWCNT/PDMS composite is essential to enhance the electrical conductivity by controlling MWCNT content and maintaining electrode flexibility. Thus, this study disperses the MWCNT/PDMS composite using a solution mixing method: sonication process and mechanical stirring. The MWCNT is dispersed using toluene solvent to achieve uniform dispersion, where the MWCNT content varies from 2 wt% to 10 wt% in PDMS matrix. As a result, the MWCNT/PDMS composite conductivity is in the range of 0.30 × 10-9 S/cm to 6.14 × 10-6 S/cm. At 4 wt%, the MWCNT/PDMS composite reached the percolation threshold region. The fabricated polymer composite was further characterised in Raman spectroscopy and the measurement shows vibration peaks in the D-band at 1349 cm-1 and G-band at 1585 cm-1. This proves the dispersion of MWCNT in PDMS. In addition, the intensity of the D-band and G-band, ID/IG decreases when the MWCNT/PDMS concentration increases, indicating less defect of MWCNT during the sonication process. These findings show that the MWCNT/PDMS has the potential as an excellent polymer composite electrode.