New Wearable Sensor for Continuous Monitoring of Glucose, Alcohol and Lactate

Engineers at the University of California, San Diego (UCSD) developed a prototype of a wearable sensor for continuous monitoring of glucose, alcohol and lactate.

High-tech step counters like Fitbit have increased in popularity as wearers can track their daily steps and calories burned with the watch-like device that uses accelerometers and altimeters to track how much they move throughout the day. Some may wear it while sleeping to track their sleep quality. The information gathered by this device can motivate people to move more throughout the day or see a specialist for sleep issues — both of which can improve their health!

For those with chronic conditions like diabetes, tracking different health biomarkers can be of value. Although glucometers can measure blood glucose levels, blood glucose can be impacted by other variables not measured by glucometers.

Recently, a group of engineers at the University of California, San Diego (UCSD) Center for Wearable Sensors developed a prototype of a wearable sensor that continuously monitors not only glucose, but alcohol and lactate as well. The simultaneous tracking of these biomarkers can help diabetic patients better understand how their glucose levels are affected by exercise and alcohol, all from their smartphone. The UCSD researchers published an article on May 9 in Nature Biomedical Engineering that describes their new device.

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Engineering a Continuous Monitoring Device

Most commercially available glucometers only measure glucose levels, excluding a lot of other health information. For example, consuming alcoholic drinks lowers blood glucose, so monitoring alcohol levels can help diabetics make decisions about their health before their glucose levels get too low. Lactate is a biomarker related to physical activity, which also influences glucose sensitivity and regulation.

The device is described by Joseph Wang, nanoengineering professor at UCSD and co-author of the study, as “a complete lab on the skin.” Wang states “it is capable of continuously measuring multiple biomarkers at the same time, allowing users to monitor their health and wellness as they perform their daily activities.”

The device itself is inconspicuous. It is attached painlessly to the upper arm skin through tiny microneedles that barely puncture the skin — just enough to be in contact with the interstitial fluid that surrounds the cells under the skin. The microneedle tips contain enzymes that react with the molecules of interest in the interstitial fluid. The reaction generates electrical currents that the sensors can read and analyze, and the attached electronics case wirelessly sends the real-time data to the wearer’s smartphone where it is visualized.

Other key features of the device include reusability (the electronics case can be detached from the disposable microneedle patch and charged wirelessly), cost-effectiveness in manufacturing and easy assembly.

Although further investigation is required, the results of the preliminary study are positive. In the initial trial, the device was tested on five volunteers who wore it on their arm while eating, drinking a glass of wine and exercising, causing changes in their glucose, alcohol and lactate levels, respectively. These biomolecules were measured by the device and closely matched results generated by a commercial glucose monitor, breathalyzer and blood lactate measurement. Additionally, the levels measured in the interstitial fluid correlated with levels in the blood.

Small Wearable Sensors with Big Results

The two first co-authors of the study, Farshad Tehrani and Hazhir Teymourian, have commercialization plans for the tiny sensor after improving the technology. The device will be tested within a larger population, and the sensor readings will be validated through laboratory testing to ensure the quality of the real-time measurements of several biomarkers at once. Additionally, they will investigate the longevity of the microneedle patch and the possibility of adding more sensors to read medication levels.

Numerous wearable health devices have been developed in previous years, some of which can also measure several biomarkers at once. Earlier this year Abbott announced the development of a wearable sensor called Lingo. It aims to track glucose, ketone and lactate levels to help people track their general health and make healthier decisions — Abbott also plans to add alcohol to the list.

Wearable devices can be valuable to the public. Wearers can use the continuously monitored data to make more informed decisions about their health in different contexts such as athletic training or disease management and develop a better understanding of the relationship between the biomolecules.