Recent advances in thermal management include so-called anisotropic thermal conductors. In these materials, heat flows faster in one direction than the other.
Many natural crystal structures are strongly anisotropic conductors of heat—for example, in the case of graphite, heat conducts along its fast axis about 340 times faster than its slow axis. However, these natural materials are often difficult to use in large-scale manufacturing techniques and may lack various electrical or optical properties required for devices. In contrast, most artificial structural materials are poor anisotropic thermal conductors, typically having a fast-to-slow heat flux ratio of less than 20 at room temperature.