Well-reputed deposition methods like chemical vapor deposition (CVD), physical vapor deposition (PVD), and atomic layer deposition (ALD) are simply too complicated for the public. Although solution-based deposition techniques generally feature with easy operation, typical examples of sol-gel, dip-, spin-coating, and drop-casting still need high temperature annealing to consolidate the adhesion of coatings on substrates. The public interests may be significantly decreased due to the inconvenience of additional heating step, and also forbidden toward some soft-substrate devices with low thermal durability. Ambient deposition procedures capable of achieving strong adhesion on generic substrates are therefore highly preferred. Typically, copper, zinc, and silver cations have intrinsic antimicrobial activities against a wide spectrum of bacteria, viruses, and other microorganisms, which can be caused by disruption of cell membranes/coatings, or oxidative damage due to reactive oxygen species. Thus, a thin metal oxide layer containing these three bioactive metals is proposed to provide exceptional antimicrobial activities. In the literature, these cations have been successfully incorporated into oxide-based coatings for bone implant and stainless steel substrates. Nevertheless, easy procedures capable of combining all these cations into one continuous, invisible coating have been too challenging already. This would be even more difficult with the criteria of room-temperature conditions on generic substrates.