Breakthrough: Temporary tattoos also serve as medical sensors


By Peter Schelden on 07/16/2020 2:00 PM

Source: MedicineNet Health News

Scientists devised a disposable tattoo made from pencil and paper that could monitor blood sugar levels, observe sleep patterns, and administer medication. Sounds made up, right? Well, they built it, and it works.

Their invention could bring essential health services to poor and remote parts of the world and make home health care easier and more affordable.

The study authors explain that by using widely available paper and pencils that are 93% graphite, healthcare workers could save costs and production time compared to available biomedical sensors.

“The conventional approach to developing an electronic biomedical device on the skin is generally complex and often expensive to produce,” said Zheng Yan, assistant professor at the University of Missouri. “On the other hand, our approach is inexpensive and very simple.

This no-frills approach to monitoring the body’s many health signals could be used in a number of ways. Different tattoo designs could check a patient’s temperature, monitor muscle responses, and test the pH balance of sweat, for example.

How it works

The reason these simple tattoos work boils down to electricity. The pencils are made with different combinations of wax, clay and graphite. And it is this graphite that makes the difference.

Researchers have found that pencils made with 90% or more graphite can conduct electricity. And they found the ideal ratio of graphite to be 93%.

These designs work best when used with a spray adhesive, Yan said. This keeps them tight against the skin.

With the ability to conduct electricity, these specially designed tattoos can be made into antennas and circuits that transmit specific information to help healthcare workers diagnose and monitor patients.

Why simple paper and pencil can be the best

Besides the low cost, a paper-and-pencil monitor could have other health care benefits.

On the one hand, it is painless. An important goal of diabetes control is to keep blood sugar levels within a healthy range, explains MedicineNet medical author Melissa Conrad Stöppler, MD. To do this, people with diabetes must prick their fingertips for a blood test before and after meals, as well as before bed, she says.

On the other hand, a tattoo at home would not require any blood test.

Another big advantage is for the environment. Paper-based sensors are biodegradable and easily dissolve in water. This has the potential to ease the burden of some broken and obsolete medical equipment.

Indeed, as part of their article published in the Proceedings of the National Academy of Sciences, researchers demonstrate how their tattoos can dissolve in water after a few minutes of stirring.

Another useful advantage is the potential flexibility of these devices. Researchers suggest a variety of possible monitoring applications, including:

  • skin temperatures
  • electrocardiograms
  • electromyograms
  • alpha, beta and theta rhythms
  • instant heart rate
  • respiratory rate
  • sweat pH
  • Uric acid

Looking ahead, Yan says his research group will continue to develop and test their devices to monitor electrical and biochemical signals, as well as body temperature.


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