Graphene active sensors have demonstrated outstanding capabilities for the detection of electrophysiological signals in the brain. Their functional properties, together with their flexibility as well as their expected stability and biocompatibility have raised them as a promising building block for large-scale sensing neural interfaces. However, in order to provide reliable tools for neuroscience and biomedical engineering applications, the maturity of this technology must be thoroughly studied. Here, we evaluate the performance of 64-channel graphene sensor arrays in terms of homogeneity, sensitivity and stability using a wireless, quasi-commercial headstage and demonstrate the biocompatibility of epicortical graphene chronic implants. Furthermore, to illustrate the potential of the new technology, we perform proof-of-concept long-term wireless recording of wide frequency band epicortical dynamics in a freely behaving rodent and show a wide range of novel observations on the infra-slow cortical signals. Our work demonstrates the maturity of the graphene-based technology, which represents an outstanding candidate for chronic, wide frequency band neural sensing interfaces, holding a great promise for future research on the origin and links between neural dynamics across wide frequency band.