Wearable Sensors Printed Directly on Skin with No Heat

Researchers have printed sensors directly on human skin without the use of heat. The fabrication technique uses a novel sintering aid layer to enable direct printing for on-body sensors. By adding a nanoparticle to the mix, the silver particles sinter at a lower temperature of about 212 °F (100 °C). The room-temperature sintering aid layer consists of polyvinyl alcohol paste — the main ingredient in peelable face masks — and calcium carbonate — which comprises eggshells. The layer reduces printing surface roughness and allows for an ultrathin layer of metal patterns that can bend and fold while maintaining electromechanical capabilities. When the sensor is printed, the researchers use an air blower, such as a hair dryer set on cool, to remove the water that is used as a solvent in the ink.