Researchers From Duke University Developed Print-in-Place Electronic Tattoos

Most wearable electronics today come in proven forms, such as smartwatches. But a lot of effort is being put in developing various kinds of patch-style wearables that contain sensors to monitor the wearer’s vital signs, movement, and other useful metrics. Despite the many advances that have been made in that area, those patches do still need to be manufactured in a factory using fairly traditional fabrication techniques. These new electronic tattoos, however, could be printed directly onto a user’s skin whenever they’re needed.

“Tattoo” may be a bit misleading, as these are not permanent. Instead, they’re more akin to henna tattoos that will wear away eventually. They were developed by researchers from Duke who were looking for a way to apply custom wearable electronic circuits directly to delicate surfaces—including human skin and paper. That has proven to be a difficult challenge in the past, as most flexible circuit fabrication techniques require high-temperature baking in order to cure the “ink” or substrate. These new electronic tattoos can be printed at low temperatures, and dry at room temperature. That means they can be applied to your skin without pain or damage.

That is achieved with an aerosol printer that sprays a special ink full of silver nanowires onto the skin. If multiple layers are required, as with a transistor, semiconducting carbon nanotubes or non-conductive dielectric hexagonal boron nitride can be printed. The Duke team has demonstrated a basic circuit printed on graduate student Nick Williams’ pinky finger. That circuit just has two traces that illuminate an LED when voltage is applied. But the same printing technique could be used to create more complex electronic tattoo circuits. Theoretically, medical professionals could customize those circuits and then print them directly onto a patient in order to create a biomedical monitoring device specific to their needs.