Every cell's outer membrane, including that of a single cell organism like a bacterium, is characterized by a stable electrical micro-current. This is often called "transmembrane potential", and is, literally, a voltage difference between the inside and the outside of a cell. It is strongly suspected that when a bacterium comes in contact with a copper surface, a short circuiting of the current in the cell membrane can occur. This weakens the membrane and creates holes.

在膜上打孔的另一种方法是局部氧化或“生锈”。当单个铜分子或铜离子从铜表面释放并撞击细胞膜的组成部分（蛋白质或脂肪酸）时，就会发生这种情况。如果“撞击”发生在有氧气的情况下，我们就说“氧化损伤”或“生锈”。一个类比是锈蚀减弱并在一块金属上打孔。

Another way to make a hole in a membrane is by localized oxidation or "rusting." This happens when a single copper molecule, or copper ion, is released from the copper surface and hits a building block of the cell membrane (either a protein or a fatty acid). If the "hit" occurs in the presence of oxygen, we speak of "oxidative damage", or "rust." An analogy is rust weakening and making holes in a piece of metal.