High-performance elastomeric strain sensors based on nanostructured carbon fillers for potential tire applications

For the development of intelligent vehicle tires, especially for future self-driving cars, suitable strain sensors are mandatory. The design of such a strain sensor must fulfil several criteria, most important of all, it must be easily mounted or implanted into the tire and the elastic nature of the sensors must be synchronized with the deformation behaviour of the tire. To our knowledge, we evaluate for the first time, the piezoresistive characteristics of a composite developed from tire rubber, taking into account the morphology (distribution and dispersion of the fillers), filler network structure, crosslinking density and the stiffness (hardness) of the rubber matrix. We use a commercially available synthetic solution polymerized styrene butadiene rubber (SSBR) which is widely used in modern car tire industries. As the internal structure of the filler particles can rearrange or alter during deformation, it is extremely important to study the piezo-resistive performance with respect to crosslinking density, hardness and modulus of the rubber composites in details. The present paper focusses on the development of strain sensors by exploiting conductive elastomeric composites based on SSBR with conducting carbon fillers like carbon black and carbon nanotubes. The sensors can be stretched to several hundred percent of their original length and a sensitivity could be achieved as much as ∼1000 (gauge factor) in a given strain regime of ∼100%, while maintaining the mechanical robustness. Some of the mechanical properties like tensile strength (∼20 MPa), and modulus at 100% elongation are found to be quite satisfactory indicating the suitability of the materials for real applications.