Electronic Tattoo Offers Highly Accurate, Continuous Blood Pressure Monitoring

One of the most crucial markers of heart health is blood pressure, but it's challenging to measure it regularly and accurately outside of a hospital environment. The industry standard for many years has been cuff-based devices that tighten around the arm to provide a reading. But now, scientists at Texas A&M University and The University of Texas at Austin have created an electronic tattoo that can be comfortably worn on the wrist for hours while providing continuous blood pressure measurements with an accuracy level that surpasses nearly all options currently on the market.

“Blood pressure is the most important vital sign you can measure, but the methods to do it outside of the clinic passively, without a cuff, are very limited,”  stated Deji Akinwande, a professor in the Department of Electrical and Computer Engineering at UT Austin and one of the co-leaders of the study, which is described in a new publication released on June 20, 2022, in Nature Nanotechnology.

If high blood pressure is not addressed, it might cause significant cardiac issues. Since a standard blood pressure check only measures one specific point in time, or one data point, it might be challenging to quantify.

“Taking infrequent blood pressure measurements has many limitations, and it does not provide insight into exactly how our body is functioning,” according to the project's other co-leader and Texas A&M professor of biomedical engineering, computer science, and electrical engineering, Roozbeh Jafari.

Blood pressure readings may be taken at any time, including during periods of high stress, when sleeping, working out, etc., thanks to the e-continuous tattoo's monitoring. More measures than any other gadget to date can be delivered by this one.

In recent years, technology like smartwatches has significantly advanced mobile health monitoring. These gadgets employ metallic sensors, which collect data from LED light sources that are shone through the skin.

Leading smartwatches, however, are not yet capable of measuring blood pressure. This is due to the difficulty in providing precise readings caused by the timepieces' tendency to slide about on the wrist and potential distance from arteries. Additionally, measurements based on light might be inaccurate in those with darker skin tones or broader wrists.

One of the strongest and thinnest substances in use, graphene is a crucial component of the e-tattoo. Although the atoms are neatly organized into tiny layers, it is comparable to the graphite found in pencils.

Because the sensors are enclosed in a sticky, stretchy material that is comfortable to wear for extended periods of time and does not slide about, e-tattoos make sense as a platform for mobile blood pressure monitoring.

“The sensor for the tattoo is weightless and unobtrusive. You place it there. You don’t even see it, and it doesn’t move,” according Jafari. “You need the sensor to stay in the same place because if you happen to move it around, the measurements are going to be different.” 

By injecting an electrical current into the skin and evaluating the body's reaction, or bioimpedance, the gadget makes measurements. A relationship exists between bioimpedance and variations in blood pressure that are related to variations in blood volume. The researchers had to develop a machine learning model to examine the link since the association is not especially clear in order to obtain correct blood pressure measurements.

According to Jafari, cuff-free blood pressure monitoring is the "holy grail" of medicine, but there isn't a workable solution available just now. It is a part of a bigger medical effort to utilize technology to free patients from mechanical dependence while gathering more data wherever they are, enabling them to move between rooms and clinics while still receiving individualized treatment.

“All this data can help create a digital twin to model the human body, to predict and show how it might react and respond to treatments over time,” Akinwande stated.

Reference: “Continuous cuffless monitoring of arterial blood pressure via graphene bioimpedance tattoos” by Dmitry Kireev, Kaan Sel, Bassem Ibrahim, Neelotpala Kumar, Ali Akbari, Roozbeh Jafari and Deji Akinwande, 20 June 2022, Nature Nanotechnology.

DOI: 10.1038/s41565-022-01145-w