High sensitivity of multi-sensing materials based on reduced graphene oxide and natural rubber: The synergy between filler segregation and macro-porous morphology

Elastomeric conductive composites (ECCs) based on carbonaceous fillers are very attractive and play a significant role in the field of smart sensors due to their excellent flexibility, high and wide-spectrum sensitivity as well as fast response to external stimuli. In this study, a lightweight and multi-sensing composite based on reduced graphene oxide/natural rubber (rGO/NR), is fabricated by a facile and cost-effective approach that combines the rGO assembling on rubber latex particles by graphene oxide in-situ reduction and mild drying of the resulting hydrogels. The resulting composites exhibit a reliable porous structure whereas the rGO is spatially distributed in a three-dimensional segregated morphology that percolates the samples. The composites are characterized by a low percolation threshold (<0.45 vol%), high sensitivity to compression strain (gauge factor equal to 77.64), organic solvents (i.e. toluene and tetrahydrofuran) and temperature (range of detectability is 35-90 degrees C). The elastomeric composites are proposed for the realization of innovative multi-purpose, wide-spectrum and high-sensitivity wearable sensors for monitoring the motion and temperature of human body in real time.