Their findings are published in the journal Proceedings of the National Academy of Sciences.

Zheng Yan, an assistant professor in the College of Engineering, said many existing commercial on-skin biomedical devices often contain two major components -- a biomedical tracking component and a surrounding flexible material, such as plastic, to provide a supportive structure for the component to maintain an on-skin connection with a person's body.

"The conventional approach for developing an on-skin biomedical electronic device is usually complex and often expensive to produce," he said. "In contrast, our approach is low-cost and very simple. We can make a similar device using widely available pencils and paper."

Since its invention, pencils -- made of lead including various levels of graphite, clay and wax -- have often been used for writing and drawing. In the study, the researchers discovered that pencils containing more than 90% graphite are able to conduct a high amount of energy created from the friction between paper and pencil caused by drawing or writing. Specifically, the researchers found pencils with 93% graphite were the best for creating a variety of on-skin bioelectronic devices drawn on commercial office copy paper. Yan said a biocompatible spray-on adhesive could also be applied to the paper to help it stick better to a person's skin.

The researchers said their discovery could have broad future applications in home-based, personalized health care, education and remote scientific research such as during the COVID-19 pandemic. Yan said the group's next step would be to further develop and test the use of the biomedical components, including electrophysiological, temperature and biochemical sensors.

"For example, if a person has a sleep issue, we could draw a biomedical device that could help monitor that person's sleep levels," he said. "Or in the classroom, a teacher could engage students by incorporating the creation of a wearable device using pencils and paper into a lesson plan. Furthermore, this low-cost, easily customizable approach could allow scientists to conduct research at home, such as during a pandemic."

An additional benefit to their approach, Yan said, is that paper can decompose in about a week, compared to many commercial devices that contain components that are not easily broken down.

Story Source:

Materials provided by University of Missouri-Columbia. Note: Content may be edited for style and length.

Journal Reference:

1. Yadong Xu, Ganggang Zhao, Liang Zhu, View Orcid Profileqihui Fei, Zhe Zhang, Zanyu Chen, Fufei An, Yangyang Chen, Yun Ling, Peijun Guo, Shinghua Ding, Guoliang Huang, Pai-Yen Chen, Qing Cao, and Zheng Yan. Pencil-paper on-skin electronics. PNAS, 2020 DOI: 10.1073/pnas.2008422117