Enhanced electromechanics of morphology-immobilized co-continuous polymer blend/carbon nanotube high-range piezoresistive sensor

This study reports the development of novel piezoresistor which offer excellent sensitivity for strain measurements, can be used for the detection of high compressive stress and have low creep and fatigue characteristics. Morphology immobilized composites of hard-soft polyolefin blends with co-continuous (co-PEP) and dispersed (d-PEP) morphology were prepared by melt compounding polyolefin blends with Multiple-Walled Carbon Nanotubes (MWCNT) followed by radiation crosslinking. In comparison to d-PEP/MWCNT composites, co-PEP/MWCNT composite exhibited superior electromechanics, in terms of strain sensing range and gauge factor, along with low hysteresis. Most importantly, d-PEP did not exhibit compressive stress-dependent piezoresistivity whereas co-PEP showed reversible piezoresistivity in the range 25 kPa-1 MPa, which is considerably higher than the highest stress-sensing limit typically observed in MWCNT based systems. Fractal dimension analysis of MWCNT network using non-linear rheology revealed that co-PEP/MWCNT composites exhibit soft-aggregates contact breakage and had a much milder dependence on MWCNT volume fraction than binary composites. The cyclic and creep measurements confirmed excellent recovery under static and dynamic conditions, revealing the high potential of such material for standalone stress sensors for robotics, human-machine interfacing, and intelligent transport monitoring.