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‘A laboratory on the skin’: UC San Diego lab works to make new wearable health sensors part of our daily look

Health-monitoring sensors wearable on the skin are being developed in the lab of UC San Diego professor Joseph Wang.
(Courtesy of Joseph Wang)

Wearing a small patch that monitors health information may soon become as much a part of our daily routines as putting on clothes, a UC San Diego professor believes.

Joseph Wang, who works in UCSD’s Department of Nanoengineering and directs its Center for Wearable Sensors, said during a Feb. 8 virtual lecture presented by the La Jolla Community Center that we might be only months away from wearing “a laboratory on the skin.”

Wang detailed his work in “striving to meet the challenges of developing the next generation of wearable sensors,” noting that such sensors have come a long way from the rigid, invasive devices that have been around for decades.

The sensors developed by Wang’s lab are small, lightweight, flexible, patch-like devices that appear similar to temporary tattoos and follow his vision to “shrink a big laboratory” onto the skin.

As health care moves further into precision medicine — tailoring diagnostics or therapeutics based on patients’ genetic and physiologic characteristics — wearable sensors can be a key tool, he said.

UCSD nanoengineering professor Joseph Wang
UCSD nanoengineering professor Joseph Wang says he is “striving to meet the challenges of developing the next generation of wearable sensors.”
(Courtesy of La Jolla Community Center)

The highly sensitive electrochemical sensors that Wang’s lab has developed are an evolution from current devices worn around the wrist or finger to track mobility and vital signs like heartbeat.

“What was missing is the molecular information,” such as glucose, cortisol or electrolyte levels, Wang said.

His lab has worked on collecting that information continuously, non-invasively and digitally. The new wearable sensors also are made to be low-cost, with low energy use. The technology likely will be licensed, with prices set by local companies.

Wang said he has worked on various prototypes, all of which analyze body fluids for “different molecular biomarkers” to monitor nutrition and wellness.

Most types of sensors worn on the skin measure components in the sweat, he said. “The skin is the gateway to … our biochemistry.”

Combining printing and tattoo technology, the skin sensors contain electrodes and are very flexible and thin, a departure from inflexible devices and rigid electrodes, Wang said. They will stretch, bend and twist with the body.

“Our biology is very soft,” he said. “Our goal is to bridge the gap between the softness of biology and the hardness and the rigidity of” previous devices.

The sensors adhere all day without piercing the skin, Wang said. They can measure biomarkers like glucose every 20 minutes, transferring the data electronically to health professionals and one’s smartphone.

They also can be used to measure alcohol oxidants via sweat. “It takes two minutes … to tell you how drunk you are” via your mobile phone, Wang said.

Wearable health sensors being developed by Joseph Wang’s lab are thin, lightweight and flexible.
(Courtesy of Joseph Wang)

The technology, which Wang said companies are already using in Sweden, also can help personalize one’s diet, as people absorb vitamins differently. Taking a measurement via the skin 20 minutes after swallowing a vitamin pill can “tailor the nutrition to the person based upon the specific kinetic metabolism of the vitamins,” Wang said.

In addition, the sensors can check electrolyte, sodium and potassium levels, helping lead to “optimal nutrition on a personal level,” he said.

And they can measure blood pressure and other vital signs.

“You take your coffee, you can measure caffeine or stress,” Wang said. “You have your cheesecake, you can monitor your glucose. You exercise, you see the blood pressure changing.”

His lab is working with Parkinson’s disease researchers at UCSD to use the sensors to monitor the effectiveness of levodopa treatments in Parkinson’s patients.

The sensors also can detect enzymes known to appear in melanoma cases, enabling “rapid screening of potential skin cancer,” Wang said.

He added that he is able to monitor wound healing by printing pH sensors on a bandage, since pH level is a “very important biomarker” in healing.

Outside the body, Wang said, “we can monitor the surrounding environment for explosives or nerve agents.”

But this type of sensor isn’t just skin-deep. Wang’s laboratory also is working on sensors for inside the mouth, a place he said contains “a lot of salivary biomarkers.”

And contact lens sensors can be used to measure glucose in tears, he added.

Slightly more invasive are microneedle sensors, with an array of 64 electrodes on a 1-inch sensor. This project to “create a lab under the skin that is minimally invasive and painless” can monitor several biomarkers simultaneously, Wang said.

He said a La Jolla firm is in the final trial stages for approval by the U.S. Food and Drug Administration for a microneedle sensor, and he anticipates the sensor will launch by the end of 2023.

He said he expects the noninvasive sensors to be approved soon.

Efforts to develop wearable health sensors have accelerated during the COVID-19 pandemic as guidelines to stay distanced from others led to upticks in telemedicine and remote health monitoring, Wang said.

But progress in developing devices for the skin has been hindered by a lack of anatomically compliant power sources, he said. He added that his lab is working on ways to power the sensors without batteries, using the body’s energy instead.

“You can even go to sleep; we call it the … power of dreaming,” Wang said.

To reach Wang, email josephwang@eng.ucsd.edu.