Xiaolei Wang, and his colleagues from NanChang University, have developed antibacterial materials based on silver nanoparticles enclosed in carbon membranes that act as switchable capsules. These switchable smart bandages, when pressed, causes the layers to interact, releasing the active silver particles and changing the color from white to orange, showing the bandage is on.

Source: http://www.rsc.org/chemistryworld/2016/04/smart-bandage-press-antibacterial-antibiotic