The compact “skin laboratory” regularly monitors glucose, alcohol and lactate.

The device can be worn on the upper arm, and the user spends the day. Credit: Nanobioelectronics Laboratory / UC San Diego

You can measure your blood sugar levels, find out if you drink too much alcohol, and watch your muscles for fatigue during exercise, all in a small device attached to your skin. Engineers at the University of California, San Diego (UCSD) have developed a prototype of such a device that can continuously monitor multiple health statistics in real time – glucose, alcohol and lactate levels.

“It’s like a complete lab on the skin.” – Joseph Wang

The multi-tasking device is about the size of a six-quarter stack. It is applied to the skin using Velcro-like microscopic needles or micro-needles, each of which is about one-fifth the width of a person’s hair. Wearing the device is painful – micro-needles barely penetrate the surface of the skin to detect biomolecules in the interstitial fluid, which is the fluid that surrounds the cells under the skin. The device can be worn on the upper arm and wirelessly sends data to a special application on the smartphone.

Researchers at the UC San Diego Wear Sensors Center describe their device in a paper published in the journal today (May 9, 2022). Natural Biomedical Engineering.

The device can be worn on the upper arm and wirelessly sends data to a special application on the smartphone. Credit: Nanobioelectronics Laboratory / UC San Diego

“It’s like a complete laboratory in the skin,” said Joseph Wang, director of the center, a professor of nanoengineering at the University of San Diego and a correspondent for the paper. “It is capable of continuously measuring multiple biomarkers at the same time, allowing users to monitor their health and well-being as they perform their day-to-day activities.”

Most commercial health monitors, such as regular glucose monitors for patients with diabetes, measure only one signal. Researchers say that this problem has left behind information that could help people with diabetes, for example, to better manage their disease. Controlling alcohol levels is helpful because alcohol lowers glucose levels. Awareness of both levels prevents people with diabetes from falling too low after drinking blood sugar. As a biomarker of muscle fatigue, it is also useful to combine information about lactate, which can be observed during exercise, because physical activity affects the body’s ability to regulate glucose.

“With our equipment, people can see the link between a sharp rise or fall in glucose through diet, exercise and alcohol consumption. It could add to their quality of life, ”said Farshad Tehrani, a candidate of nanoengineering. A student at Van’s laboratory and one of the first authors of the study.

Micro needles are integrated with electronics

The tape consists of a micro-needle patch attached to the electronics housing. Various enzymes at the tips of micro-needles react with glucose, alcohol and lactate in the interstitial fluid. These reactions are analyzed by electronic sensors and generate small electrical currents that are wirelessly connected to the application developed by the researchers. The results are displayed on the smartphone in real time.

Disposable Microneedle Patch

Details of the disposable micro-needle patch from the reusable e-box. Credit: Nanobioelectronics Laboratory / UC San Diego

The advantage of using micro-needles is that they are directly sampled from the interstitial fluid, and studies have shown that the biochemical levels measured in that fluid are well matched to those in the blood.

Patrick Mercier, professor of electrical and computer engineering at the University of San Diego and co-author of the paper, said: “We start with this technology in a really good place in terms of clinical validity and relevance.” “This reduces barriers to clinical translation.”

The disposable micro-needle patch can be removed from the electronic box for easy replacement. The reusable electronic case contains batteries, electronic sensors, wireless transmitters and other electronic components. The device can be recharged on any wireless charging platform used for phones and smart watches.

Multifunctional Microneedle wearer recharge

The device can be recharged on a ready-made wireless charging platform. Credit: Nanobioelectronics Laboratory / UC San Diego

Combining all these components into one small, wireless wearer was one of the team’s biggest challenges. It also required some clever design and engineering to combine reusable electronics that had to remain dry with a micro-needle patch that had been exposed to biological fluids.

“The beauty of this is that it’s a fully integrated system that anyone can wear without being tied to desk equipment,” said Mercier, co-director of the Center for Wear Sensors at UC San Diego.

testing

The wearable device was tested on five volunteers who wore the device on the upper arm, exercising, eating, and drinking a glass of wine. The device was used to continuously monitor subjects ’glucose levels simultaneously with their alcohol or lactate levels. Measurements of glucose, alcohol and lactate obtained by the device were closely coordinated with the measurements of blood glucose in a commercial monitor, Breathalyzer and laboratory blood lactate.

Next steps

Farshad Tehrani and Hajir Teymurian, the first author to be a former post-doctoral researcher in Wang’s lab, founded a startup called AquilX to further develop the technology for commercialization. The next steps include checking and improving how long the micro needle patch will last before it is replaced. The company is also excited to be able to add more sensors to the device to monitor drug levels in patients and other health-related signals.

Reference: Farshad Tehrani, Hajir Teymurian, Brian Wurstle, Jonathan Kavner, Ravi Patel, Allison Furmidge, Reza Agawali, Hamed Hosseini-Tudeshki, Fangyu. , Zhenxin Lee, Abbas Barfidoht, Lu Yin, Paul Warren, Nicki Huang, Zina Patel, Patrick P. Mercier and Joseph Wang, May 9, 2022, Natural Biomedical Engineering.
DOI: 10.1038 / s41551-022-00887-1

Funding: NIH / National Institute of Neurological Disorders and Stroke

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