Wearable bioelectronic devices that stick to the skin and measure things such as temperature, heart rhythms, and other vitals are typically complex devices that use modern materials to do their job. They tend to be difficult to manufacture, expensive, and fragile, and so are still not widely available.
Incredibly, researchers at the University of Missouri have now come up with a way of using nothing but graphite pencils and office paper to create highly functional bioelectronic devices. They report their findings in the Proceedings of the National Academy of Sciences. To show the vast swath of what is possible, the team developed on-skin devices that can measure body temperature, sense electrocardiography signals (ECG), and assess sweat for pH, uric acid, and glucose. They also created a transdermal drug-delivery device that can be worn on the skin for extended therapy and an electric harvester that uses humidity to generate power, that may be useful to power the skin-worn electronics.
The Missouri team discovered that pencils rich in graphite (over 90%) conduct enough electricity for common biomedical sensing applications. Different patterns drawn on conventional office paper act as the sensors and more complex devices, such as the energy harvester, are just layered pieces of paper and more graphite ink. Reportedly, the approach is so easy to use that patients themselves will be able to draw sensors on paper and apply them without leaving home.
“For example, if a person has a sleep issue, we could draw a biomedical device that could help monitor that person’s sleep levels,” said Zheng Yan, the corresponding author of the study. “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.”
The technology has numerous benefits, such as low price, fantastic accessibility, low environmental impact, and during the ongoing COVID-19 pandemic there’s certainly something to being able to independently create and use medical sensors.
The Missouri team promises to continue expanding their methodology to create other devices for body monitoring and expand their approach for other uses.
From the study abstract in Proceedings of the National Academy of Sciences:
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 pencil-drawn 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. 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.
Study in PNAS: Pencil–paper on-skin electronics