“epidermal electronics” pencil and paper skin sensors

"One day, people could monitor their own health conditions by simply picking up a pencil and drawing a bioelectronic device on their skin. In a new study, University of Missouri engineers demonstrated that the simple combination of pencils and paper could be used to create devices that might be used to monitor personal health."

paywalled paper: https://www.pnas.org/content/early/2020/07/09/2008422117