Posted in | Medical Sensor | Biosensors

Sweat Holds the Most Promise for Noninvasive Testing, Concludes Study

Creating an innovative biosensor requires blood, sweat, and tears. And saliva, obviously. University of Cincinnati professor Jason Heikenfeld analyzed the capacity of these and other biofluids to check human health with small, portable sensors for the journal Nature Biotechnology.

UC’s sweat technology could have wellness applications apart from diagnosing illness or monitoring medicine. (Image credit: Lisa Ventre/UC Creative Services)

Heikenfeld creates wearable technology in his Novel Device Lab at UC’s College of Engineering and Applied Science. Last year, his lab developed the world’s first continuous-testing device that samples sweat as successfully as blood but in a noninvasive manner and for several hours.

“Ultimately, technological advances in wearables are constrained by human biology itself,” the study reported.

Heikenfeld’s innovations show UC’s dedication to research as summarized in its strategic plan, known as Next Lives Here.

Notably, most of the breakthroughs in the field of biosensors and sweat technology were made in Cincinnati. The first glucose monitor for diabetes was commercialized in Cincinnati. The world’s first antiperspirant, known as Odorono, was invented by Abraham Murphey, a Cincinnati physician.

We have such a strong history in this field here. It’s really fascinating,” stated Heikenfeld.

Heikenfeld recognizes the hard work of his team for the success of his lab.

We have been able to go far and fast here. We resonate with a certain type of student. As much as we have brilliant faculty at UC, if we didn’t have talented students here, this technology wouldn’t exist. We would just be talking theoretically about the potential.

Jason Heikenfeld, Professor, University of Cincinnati

In the Nature article, Heikenfeld classified four waves of discovery with respect to testing human health. First, physicians started drawing and sending blood to labs in an invasive, time-consuming, and labor-intensive process that patients experience to date.

Beginning around the 1980s, scientists, including pioneering UC engineering professor Chong Ahn, created point-of-care lab tests that enabled physicians to obtain instant results. Rather than transporting samples to a lab, doctors could test samples themselves with the help of small, self-contained devices.

Dr. Ahn has been at the forefront of developing these point-of-care devices,” stated Heikenfeld.

Recently, Heikenfeld stated that they are in the middle of a third wave, that is, continuous health monitoring with wearable devices such as those developed at UC. These give data over time, thus doctors can monitor health trends rather than depending on the snapshot that is offered by a single blood test.

That’s super powerful because it tells me am I getting better? Am I getting worse?

Jason Heikenfeld, Professor, University of Cincinnati

In due course, the field will see devices implanted in the body for long-term diagnosis or monitoring, he stated. However, scientists will initially have to develop robust sensors that can offer precise information over a much longer time frame.

That’s the big challenge,” Heikenfeld said. “Sensors are chemically reactive themselves. So they don’t last.”

After analyzing the use of tears, saliva, and interstitial fluid, Heikenfeld concluded in the Nature article that sweat is the most promising for noninvasive testing as it offers comparable information as blood and its secretion rate can be controlled and determined.

In his Novel Device Lab at UC, Heikenfeld and his students have been developing new sensors on a wearable patch in the size of a Band-Aid that induces sweat even if a patient is calm and relaxing. The sensor eventually determines particular analytes that can be used by physicians to determine how the patient is reacting to drug treatment.

Heikenfeld stated that the sensors can be customized to evaluate anything from drugs to hormones to dehydration.

In 2018, the lab developed the world’s first continuous-monitoring sensor that can obtain the same health information in sweat that doctors have analyzed in blood for generations. The milestone is noteworthy since the continuous sensor enables physicians to monitor health over time to envision whether a patient’s health is recovering or deteriorating. And they can perform this in a noninvasive manner with a small patch placed on the skin that induces sweat for up to 24 hours at a time.

This is the Holy Grail. For the first time, we can show here’s the blood data; here’s the sweat data – and they work beautifully together,” Heikenfeld said.

Heikenfeld and his students published their most recent experimental discoveries in December in the journal Lab on a Chip. UC’s study traced how test subjects metabolized ethanol. The research concluded that sweat offered nearly the same information as blood to determine a drug’s presence in the body.

The latest innovation at UC marked the zenith of over seven years of research, he said.

For medications, we can use sweat to get an exact measurement of concentrations in the blood. That’s important because once we can measure concentrations of therapeutics in blood, we can look at drug dosing. And that could make current dosing look like something from the Stone Age.

Jason Heikenfeld, Professor, University of Cincinnati

Cincinnati is home to a number of companies that are revolutionizing technologies for drug prescribing, delivery, and monitoring into commercial products. The list comprises of Enable Injections, Assurex Health, and Heikenfeld’s Eccrine Systems, where he is co-founder and chief science officer.

Tongli Zhang, study co-author and computational biologist, stated that devices of these types will help doctors to offer personalized care. Zhang is an assistant professor in the Department of Pharmacology and Systems Physiology at the UC College of Medicine.

You don’t give children the same drug dose as adults. Likewise, we can specify a dose based on a patient’s weight. But some patients might have liver or kidney failure. And others might metabolize a drug 10 times faster. So the same dose might be ineffective in some patients and toxic in others.

Tongli Zhang, Assistant Professor, Department of Pharmacology and Systems Physiology, UC College of Medicine

Zhang said continuous sensors could basically transform treatments.

Personalized or individualized medicine is becoming a bigger deal. We realize it’s important. If we can understand what’s going on in the body, we can tailor the treatment accordingly,” he said.

UC is leading in developing new biosensors that Heikenfeld thinks will transform the way they monitor disease and wellness.

UC continues to build on our rich regional history in revolutionizing diagnostics through this third wave of continuous biochemical sensing.

Jason Heikenfeld, Professor, University of Cincinnati

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