Robin harmonic measure with a variable permeability parameter

In this paper we study the behavior of the solutions to the Robin problem in bounded $1$-sided NTA domains with Ahlfors-David regular boundary, generalizing the results of \cite{DavDEMM} to the case of a non constant Robin parameter. In particular, we will prove the mutual absolute continuity of the Robin harmonic measure with respect to the surface measure in the setting of variable permeability.