The extraordinary electric and thermal properties of graphene have attracted great interest for both theoretical and experimental studies due to their potential applications in modern nanotechnology. In this talk, I will discuss two experiment motivated theoretical works on graphene based nano devices.  In the first work, I will discuss the electric transport in molecular devices with graphene leads and show that these type of devices demonstrate very sharp resonance transmission due to the unique electronic structure of graphene. This makes graphene a very good candidate for building atomic scale switches, as demonstrated by experiments already. In the second work, I will discuss the recent efforts to build ultra sensitive bolometers making use of the extraordinary thermal properties of graphene. In particular, I will discuss the effects of disorder on the e-phonon thermal conductance channel and how this affects the sensitivity of the bolometers. Later experiments confirmed our discussion of the effects of disorder in such devices.