June 28, 2023 – A smartwatch can let you know lots about your health, but to guard against major threats like diabetes and heart disease, blood tests remain the gold standard – for now.
One day, a wearable patch could give you a similar information, but without the prick within the arm and the trip to the doctor's office.
The patch tracks markers in a fluid under your skin, between and around your cells, called interstitial fluid.
If you've ever seen or used a continuous glucose monitor, you've already seen a glimpse of this future. These skin patches, typically worn on the back of the upper arm, use interstitial fluid to observe blood sugar levels in real time.
Now scientists are asking themselves: What else could we measure using this technology?
“The vision is to ultimately develop a laboratory under the skin,” said Dr. Joseph Wang, professor of nanoengineering on the University of California San Diego.
The result: You can perform all laboratory tests – cholesterol, hormones, electrolytes and more – yourself. This relieves the burden on the healthcare system and provides you with real-time clinical details about your health status.
How does it work?
Sweat and saliva could also be easier to succeed in, but interstitial fluid is a greater mirror of blood. It comes out of tiny blood vessels (capillaries) and carries nutrients to the skin and removes waste products from it.
To collect this fluid, each monitor has either a tiny wire or a series of microneedles lower than a millimeter long that penetrate the skin for days or even weeks – or so long as you wear the device. “You don't feel it,” Wang said. “Once you put it on your skin, you forget it.”
The microneedles or wires are made from a polymer that absorbs the fluid, which flows to a biochemical sensor that targets the marker to be measured.
The first patents for this technology date back to the Nineties (the primary portable glucose meters for home use got here in the marketplace within the 2000s), but sensors have made great strides since then, becoming smaller, more accurate and more sophisticated.
Glucose sensors use an enzyme that responds to glucose to point its concentration within the blood. Some researchers – like Dr. Jason Heikenfeld and his team on the University of Cincinnati – are specializing in “aptamers,” short single strands of DNA that bind to focus on molecules. “You can use the body's ability to make things to find a needle in a haystack,” he said.
The big picture
With our population aging, healthcare costs rising and our medical infrastructure and workforce becoming overstretched, we’re seeing a trend toward decentralized medicine, Heikenfeld said. Like other at-home monitoring technologies, interstitial fluid measurement guarantees greater convenience and higher access to care.
“There's a lot that can be done through telemedicine, over the phone,” says Justin T. Baca, MD, PhD, associate professor on the University of New Mexico. “But we haven't figured out how to collect reliable biospecimens and analyze them remotely.”
Unlike traditional blood tests that provide a snapshot of health at a particular time limit, these devices collect data constantly, reveal trends and help doctors detect impending dangers earlier.
Take ketones, for instance, a chemical produced within the liver when fats are broken down. High levels in individuals with diabetes can result in a life-threatening condition called diabetic ketoacidosis, which regularly builds up slowly and will be missed in its early stages.
Baca and others use interstitial fluid to constantly measure ketone levels within the blood.
“It may be an early warning sign that someone needs to either be evaluated, rehydrate or get insulin,” Baca said, “a kind of early diagnosis to avoid subsequent hospital visits.”
This technology could also help us:
Treatment of chronic diseases
Seeing the health effects of medicines and weight loss program in real time could motivate patients to persist with their treatment plans, Heikenfeld said. Researchers in Taiwan are Development of a test This could help individuals with chronic kidney disease track levels of cystatin C, a protein that rises as kidney function declines. Heart patients could watch their levels of cholesterol drop over time, and diabetes patients can, after all, already track their blood sugar levels.
Monitoring of prescribed drugs
Providers could monitor drug levels in a patient's body – corresponding to antibiotics for an infection – to see how the drug is metabolized and adjust the dose as needed, Heikenfeld said.
Stress and hormone therapy
Interstitial fluid could help us measure hormone levels, corresponding to the stress hormone cortisol.
Scientists within the UK and Norway have developed a belt-worn device that constantly collects samples of interstitial fluid for up to 3 days. In their study, the samples were sent off for evaluation, but at some point the device might be fitted with a sensor to observe a single hormone in real time, said study writer Thomas Upton, PhD, a clinical research fellow on the University of Bristol in England. “There is a lot of interest in real-time monitoring of cortisol,” he said.
This may gain advantage patients with hormone deficiency, night shift employees with a disturbed circadian rhythm or anyone who desires to control their stress response.
Human performance and well-being
Athletes can use glucose and lactate monitors to optimize training, recovery time, and nutrition. Doing the keto weight loss program? A monitor could assist you adjust your carbohydrate intake based in your ketone levels. Abbott's Analyte Ventures The group is working on blood alcohol sensors to assist anyone who desires to avoid excessive alcohol consumption.
When are you able to get one?
Initial research results have been promising, but many more steps are needed before interstitial fluid sensors will be verified and approved.
Manufacturing shall be difficult. Producing these sensors at scale without sacrificing consistency or quality won't be low-cost, Heikenfeld said. Today's continuous glucose monitors have taken a long time to develop and price tons of of hundreds of thousands of dollars.
Nevertheless, the inspiration has been laid.
“As we all move more and more towards interstitial fluid, there is a proven roadmap for success that the major diagnostic companies have built up their experience on over decades,” said Heikenfeld.
Scientists are currently working on improving the sensors and considering how one can protect them from other bodily fluids during use, Wang said, but when all goes well, the result might be groundbreaking.
Wang's lab is developing a system to observe glucose and lactate, or glucose and alcohol. It might be available in as little as two years, he said.
In the subsequent decade, Wang predicts, we’ll have the ability to measure a dozen markers with a straightforward patch.