A thermosiphon cooling device including: at least one evaporator section including at least one evaporation channel arranged to receive heat and evaporate a liquid in the at least one evaporation channel and a liquid return path for delivering condensed liquid to the at least one evaporation channel, the at least one evaporation channel and the liquid return path being formed as a single, integrated part; at least one condenser section including at least one condensing channel arranged to transfer heat from evaporated liquid to a surrounding environment to condense the evaporated liquid and a vapor supply path for delivering evaporated liquid to the at least one condensing channel, the at least one condensing channel and the vapor supply path being formed as a single, integrated part; the device being characterized by a single manifold having a vapor chamber fluidly connecting the at least one evaporation channel with the vapor supply path and a liquid chamber fluidly connecting the at least one condensing channel with the liquid return path, the vapor chamber and the liquid chamber being separated by a separation wall in the manifold, for maintaining a cyclical flow in the thermosiphon device, from the evaporation channel into the vapor chamber, into the vapor supply path, into the at least one condensing channel, into the liquid chamber, into the liquid return path, and then into the evaporation channel, wherein the at least one evaporation section is received at a corresponding opening of the manifold, wherein the at least one evaporation channel is in fluid communication with the vapor chamber and the liquid return path is in fluid communication with the liquid chamber, and the at last one condenser section is received at a corresponding opening of the manifold, wherein the at least one condensing channel is in fluid communication with the liquid chamber and the vapor supply path is in fluid communication with the vapor chamber. at least one evaporator section including at least one evaporation channel arranged to receive heat and evaporate a liquid in the at least one evaporation channel and a liquid return path for delivering condensed liquid to the at least one evaporation channel, the at least one evaporation channel and the liquid return path being formed as a single, integrated part; at least one condenser section including at least one condensing channel arranged to transfer heat from evaporated liquid to a surrounding environment to condense the evaporated liquid and a vapor supply path for delivering evaporated liquid to the at least one condensing channel, the at least one condensing channel and the vapor supply path being formed as a single, integrated part; the device being characterized by a single manifold having a vapor chamber fluidly connecting the at least one evaporation channel with the vapor supply path and a liquid chamber fluidly connecting the at least one condensing channel with the liquid return path, the vapor chamber and the liquid chamber being separated by a separation wall in the manifold, for maintaining a cyclical flow in the thermosiphon device, from the evaporation channel into the vapor chamber, into the vapor supply path, into the at least one condensing channel, into the liquid chamber, into the liquid return path, and then into the evaporation channel, wherein the at least one evaporation section is received at a corresponding opening of the manifold, wherein the at least one evaporation channel is in fluid communication with the vapor chamber and the liquid return path is in fluid communication with the liquid chamber, and the at last one condenser section is received at a corresponding opening of the manifold, wherein the at least one condensing channel is in fluid communication with the liquid chamber and the vapor supply path is in fluid communication with the vapor chamber.