Percutaneous devices enable the transfer of mass, energy and forces through the skin. There is a wide clinical need for this, which is not likely to decrease or disappear. The emerging new artificial organs, such as wearable kidneys or lungs, will be in increased demand in the future. Any application lasting longer than days or weeks is endangered by infections entering the body via the exit site. The only carefree solution that has been found is for an exit site placed on the skull, where it can be securely immobilized. For the majority of the locations on the abdomen or chest, no solution for an infection-free device has been found. A solution may be possible with a better understanding of the physiology of keratinocytes as a barrier for microbes.