In some examples, a cooling system includes a silicon substrate defining a first trench, a second trench, and a plurality of channels extending between the first trench and the second trench. The silicon substrate may define a first surface and a second surface substantially opposite to and substantially parallel to the first surface, and each of the plurality of channels may extend substantially parallel to the surface of the silicon substrate. The cooling system also may include a microelectronic device comprising a heat-generating area. The microelectronic device may be attached to the first surface or the second surface of the silicon substrate. In some examples, the plurality of channels may be etched between the first trench and the second trench.