|The graphene tattoo | The University of Texas at Austin|
The greatest accuracy rating for a monitoring device of this kind has been given to a temporary graphene tattoo that measures blood pressure.
Graphene-based temporary tattoos can track blood pressure continuously for days. The method differs significantly from conventional blood pressure cuffs, which haven't undergone much improvement since they were created about a century ago.
"The tattoo made of graphene is both weightless and invisible. According to Deji Akinwande of the University of Texas at Austin, you put it on and then forget about it.
The tattoo was made by Akinwande and his colleagues, and it comprises 12 almost invisible graphene strips that are arranged in two rows along the two major forearm arteries. The inner strips of each row can then detect the response and how it varies, which can be turned into a measure of blood flow. The outermost strips of each row convey tiny electrical signals deep into the arm.
According to international standards, the tattoos can constantly measure blood pressure with "Grade A" precision, which is the highest level of accuracy attainable for a medical instrument.
The tattoos performed effectively during hours of desk work and walking, according to the team's testing on six individuals. They even functioned when participants did push-ups or submerged their arms for a minute in a bucket of icy water. Without disturbing anyone's sleep, the tattoos continued to function at night.
Currently, a lot of the equipment required to capture and analyze the data from the tattoo has to be close by and wired together. However, the group may investigate wireless connectivity in the future. According to Akinwande, another option would be to use contacts between the graphene tattoos and a timepiece worn on top of them.
A gadget that can take blood pressure when the user is moving around or sleeping may be helpful in providing a more accurate baseline reading. Team member Roozbeh Jafari from Texas A&M University adds, "We aim to get towards measuring the blood pressure continually and what I call passively, meaning that you don't even know when your blood pressure is being measured."
In contrast, a typical blood pressure monitor that takes a single reading at home or in the doctor's office may be erroneous for a variety of reasons, including elements like stress or dehydration. When they visit a doctor, some people's blood pressure even briefly increases, according to Jafari. Additionally, standard monitors typically demand users to sit rather than stand or move about.
As a light-based way of measuring blood pressure, photoplethysmography (PPG) has attracted the attention of other researchers. Popular wearables like Fitbit devices have been experimenting with this method, although PPG results can be affected by things like skin color and the layer of fat beneath the skin.
The researchers plan to test the graphene tattoos on people with high blood pressure after demonstrating their promise in healthy subjects.
Reference: Nature Biotechnology, DOI: 10.1038/s41565-022-01145-w