Preservative compositions for wood products are described. Second electrodes are arranged on the insulating layer and are perpendicular to the first electrodes. The through substrate via includes: an outer tube penetrating the substrate; at least one inner tube disposed within the outer tube; a dielectric layer lining on a side wall of the outer tube, and a side wall of the inner tube; a strength-enhanced material filling the inner tube; and a conductive layer filling the outer tube. In one embodiment, each stake includes at least two prongs that are pushed into the ground when placing the stake.