A structure. The structure includes an interposer adapted to be interposed between a heat source and a heat sink and to transfer heat from the heat source to the heat sink. The interposer includes an enclosure that encloses a cavity. The enclosure is made of a thermally conductive material. The cavity includes a thermally conductive foam material. The foam material includes pores and includes at least one serpentine channel. Each serpentine channel has at least two contiguously connected channel segments. Each serpentine channel independently forms a closed loop or an open ended loop. The foam material is adapted to be soaked by a liquid filling the pores. Each serpentine channel is adapted to be partially filled with a fluid that serves to transfer heat from the heat source to the heat sink.