Lightweight, transparent piezoresistive sensors conceptualized as anisotropic magnetorheological elastomers: A durability study

Abstract Conductive elastic composites currently dominate in research efforts on soft electronics, such as wearable and flexible sensors. Typically, the conductivity of polymeric bodies is ensured by the incorporation of fillers. Using this approach, the weight of the composite is undesirably increased and optical properties such as transparency are entirely lost; both of these factors restrict the breadth of potential applications. Herein, we report on the development of lightweight, yet transparent, piezoresistive sensors. In order to obtain the percolating systems, the filler particles were organized using the external magnetic field into chain-like structures that acted as transport pathways for electric charge. The effect of particle concentration (1 to 7 wt.%) on piezoresistivity was investigated on custom-built apparatus. In line with rise in concentration, only a slight increment in structural density was observed (ca 6.5%), although notably there was more than a 100-fold increase in conductivity. The transparency in the direction of the particle chains was preserved to a great extent. The fatigue test revealed that conductivity inevitably diminished with compression loading cycles. Thorough discussion is given to options for extending the service life of such sensors.