Pencil–paper on-skin electronics

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 117; no. 31; pp. 18292 - 18301
• Main Authors: Xu, Yadong, Zhao, Ganggang, Zhu, Liang, Fei, Qihui, Zhang, Zhe, Chen, Zanyu, An, Fufei, Chen, Yangyang, Ling, Yun, Guo, Peijun, Ding, Shinghua, Huang, Guoliang, Chen, Pai-Yen, Cao, Qing, Yan, Zheng
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 04.08.2020
• Series: From the Cover
• Subjects: Batteries; Biodegradability; Biodegradation; Drug delivery systems; Electric Power Supplies; Electrocardiography; Electrodes; Electromyography; Electronic devices; Electronic equipment; Electronics; Electronics - instrumentation; Energy harvesting; Equipment Design; Glucose; Graphite; Heart rate; Humans; Humidity; Light emitting diodes; Measurement methods; Monitoring, Physiologic - instrumentation; pH effects; Physical Sciences; Printed circuits; Respiration; Respiratory rate; Sensors; Skin; Skin temperature; Stimulators; Substrates; Sweat; Theta rhythms; Uric acid; Wearable Electronic Devices; energy harvester; pencil–paper; on-skin electronics; biophysical; biochemical
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.2008422117

Pencils and papers are ubiquitous in our society and have been widely used for writing and drawing, because they are easy to use, low-cost, widely accessible, and disposable. However, their applications in emerging skin-interfaced health monitoring and interventions are still not well explored. Herein, we report a variety of pencil–paper-based on-skin electronic devices, including biophysical (temperature, biopotential) sensors, sweat biochemical (pH, uric acid, glucose) sensors, thermal stimulators, and humidity energy harvesters. Among these devices, pencil-drawn graphite patterns (or combined with other compounds) serve as conductive traces and sensing electrodes, and office-copy papers work as flexible supporting substrates. The enabled devices can perform real-time, continuous, and high-fidelity monitoring of a range of vital biophysical and biochemical signals from human bodies, including skin temperatures, electrocardiograms, electromyograms, alpha, beta, and theta rhythms, instantaneous heart rates, respiratory rates, and sweat pH, uric acid, and glucose, as well as deliver programmed thermal stimulations. Notably, the qualities of recorded signals are comparable to those measured with conventional methods. Moreover, humidity energy harvesters are prepared by creating a gradient distribution of oxygen-containing groups on office-copy papers between pencildrawn electrodes. One single-unit device (0.87 cm²) can generate a sustained voltage of up to 480 mV for over 2 h from ambient humidity. Furthermore, a self-powered on-skin iontophoretic transdermal drug-delivery system is developed as an on-skin chemical intervention example. In addition, pencil–paper-based antennas, two-dimensional (2D) and three-dimensional (3D) circuits with light-emitting diodes (LEDs) and batteries, reconfigurable assembly and biodegradable electronics (based on water-soluble papers) are explored.