humidity sensor (IMAGE) Penn State Caption Illustration showing fabrication and application of the pencil-on-paper hydration sensor. Schematics showing the (a) fabrication processes and (b) the response mechanism of the flexible pencil-on-paper hydration sensor with (c) applications in health monitoring, noncontact switching, and skin characterizations. Credit Courtesy Huanyu “Larry” Cheng / Penn State Usage Restrictions Credit must be given to the creator. Only noncommercial uses of the work are permitted. No derivatives or adaptations of the work are permitted. License CC BY-NC-ND Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.