Synthesis of carbon nanospheres and piezoresistive study of carbon nanospheres-PEDOT:PSS nanocomposite flexible thin film for strain sensing applications

Microporous carbon nanospheres were synthesized using the single step pyrolysis method with oil palm leaves as a precursor. Non-hazardous bio-wastes from oil palm leaves were used for pyrolysis which was carried out at 700 degrees C in the nitrogen atmosphere. Nanocomposites consisting of different concentrations of carbon nanospheres(0.025 wt%, 0.05 wt%, 0.075 wt%, 0.1 wt%) and poly(3, 4-ethylenedioxythiophene) polymerized with poly(4-styrenesulfonate) polymer were prepared and were spin coated on flexible polyethylene terephthalate substrates to form nanocomposite thin films. These nanocomposite thin films were characterized for their nanostructure and elemental composition. The films were subjected to incremental strain from 0 to 6% at the speed of 0.2 mm min(-1) and subsequently evaluated for their piezoresistive response. The carbon nanospheres-poly(3, 4-ethylenedioxythiophene) poly(4-styrenesulfonate) thin film with 0.05 wt% of carbon nanospheres (which is the wt% of carbon nanospheres close to the percolation threshold) in poly(3, 4-ethylene dioxythiophene) poly(4-styrene sulfonate) exhibited highest gauge factor of 34.57 with correlation coefficient 0.869 96 at 6% strain and the highest conductivity of 39.27 S m(-1) for 0.1 wt% of carbon nanospheres was achieved. Hence, the fabricated thin film was found to be suitable in piezoresistive flexible strain sensing applications.