Imagine being able to track muscular fatigue during a workout, measure blood sugar levels, and determine if you have had too much to drink, all from a little gadget worn on the skin.
Engineers from the University of California San Diego, have created a prototype of a wearable that can continually monitor various health stats in real-time, including glucose, alcohol and lactate levels.
The gadget is around the size of a six-quarter stack. It is applied to the skin through a Velcro-like patch containing minuscule needles, or microneedles, each about one-fifth the width of a human hair.
The gadget is not painful to use since the microneedles barely pierce the skin’s surface to detect biomolecules in interstitial fluid, which is the fluid that surrounds the cells under the skin. The device is worn on the upper arm, and it wirelessly transmits data to the designated smartphone app.
In a report published on May 9th, 2022, in Nature Biomedical Engineering, researchers from the UC San Diego Center for Wearable Sensors describe their technology.
This is like a complete lab on the skin. 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.
Joseph Wang, Co-Corresponding Author and Professor, Nanoengineering, University of California San Diego
Most commercial health monitors, such as continuous glucose monitors for diabetic patients, measure only one signal. According to the researchers, it excludes information that may help patients with diabetes to control their condition.
Monitoring alcohol levels is important since alcohol can reduce glucose levels. Knowing both levels can help people with diabetes as it will allow them to monitor their blood sugar levels before they drop too low after drinking.
Combining data on lactate, which can be measured during exercise as a biomarker for muscular tiredness, is particularly beneficial since physical activity alters the body’s capacity to manage glucose.
With our wearable, people can see the interplay between their glucose spikes or dips with their diet, exercise and drinking of alcoholic beverages. That could add to their quality of life as well.
Farshad Tehrani, Study Co-First Author and PhD student, Center for Wearable Sensors, University of California San Diego
Microneedles Merged with Electronics
The wearable is made out of a microneedle patch attached to an electronics casing. Different enzymes on the microneedle tips react with glucose, alcohol and lactate in interstitial fluid.
These reactions create tiny electric currents, which are measured by electronic sensors and remotely relayed to an app built by the researchers. On a smartphone, the findings are shown in real-time.
The microneedles have the benefit of directly sampling the interstitial fluid, and studies have demonstrated that biochemical levels measured in that fluid correspond well with those in blood.
We’re starting at a really good place with this technology in terms of clinical validity and relevance. That lowers the barriers to clinical translation.
Patrick Mercier, Co-corresponding Author and Professor, Electrical and Computer Engineering, University of California San Diego
The disposable microneedle patch can be easily removed from the electronic enclosure for replacement. The reusable electronic casing holds the battery, electronic sensors, wireless transmitter, and other electronic components. The gadget can be charged using any wireless charging station that is compatible with phones and smartwatches.
One of the team’s main problems was combining all of these components into a single compact, wireless wearable. Combining the reusable electronics, which must remain dry, with the microneedle patch, and is exposed to biological fluid, also needed some innovative design and engineering.
Mercier added, “The beauty of this is that it is a fully integrated system that someone can wear without being tethered to benchtop equipment.”
The wearable was tested on five volunteers who wore it on their upper arms while exercising, eating and drinking wine. The gadget was used to continually measure the participants’ glucose levels as well as their alcohol or lactate levels.
The glucose, alcohol and lactate values collected by the device closely matched those taken in the lab by a commercial blood glucose monitor, a Breathalyzer, and blood lactate measures.
Farshad Tehrani and Hazhir Teymourian, a former postdoctoral researcher in Wang’s lab, co-founded AquilX, a startup business, to further develop the technology for commercialization. The next stage is to evaluate and improve how long the microneedle patch can endure before needing to be changed.
The business is particularly enthusiastic about the prospect of adding extra sensors to the gadget to monitor medicine levels in patients as well as other health indications.
Multi-tasking wearable prototype tracks several health stats at once
Video Credit: University of California San Diego
Tehrani, F., et al. (2022) An integrated wearable microneedle array for the continuous monitoring of multiple biomarkers in interstitial fluid. Nature Biomedical Engineering. doi.org/10.1038/s41551-022-00887-1