The hollow GrF@Ni foam etched for high accuracy health management regardless of temperature

Next-generation strain sensor with excellent sensing performance is an indispensable section for wearable applications containing smart healthcare, soft robotics and human-computer interaction. Composite sensitive materials are considered as an attractive strategy because of the possibility to combine advantages of each component. But the general preparations are complex and high cost by creating the additional component. Herein, we fabricated a novel composite only through the controllable etching of nickel (Ni) foam template, without any secondary growths on the obtained graphene films (GrF). The hollow Ni skeleton not only endows this composite with an enhanced sensitivity, but also improves its sensing accuracy by compensating the thermal current effect of GrF. The obtained hollow GrF@Ni foam has been processed into a piezoresistive sensor with excellent sensing accuracy (strain error<1.7%), high gauge factor (GF=601), fast response time (<106 ms), wide sensing range (≥80%), and good cyclic stability (≥3000 cycles). Such an ideal strain sensor can be served as wearable electronics for human health management by monitoring the pulse, heart rate and joint motions reliably even in the variable temperatures.