Health

First-of-Its-Kind Wearable Glucose Monitoring Device – No Needles Required

Researchers at Pennsylvania State University have developed the first portable non-invasive blood glucose monitoring device prototype of its kind.

Non-invasive blood glucose monitoring equipment is currently not available in the United States, so diabetics must collect blood samples or use sensors embedded under the skin to measure blood glucose levels. Now, with a new wearable device created by researchers at Penn State University, less invasive glucose monitoring may become the norm.

Led by Huanyu “Larry” Cheng, Dorothy Quiggle Career Development Professor in the Department of Engineering, Science and Mechanics at Pennsylvania State University, the researchers published detailed information on low-cost, non-invasive sensors that can detect biosensors and bioelectronics. Sweat glucose. The document is available online and will be published in the December print edition of the magazine.

The researchers first built the device with laser-induced graphene (LIG), a material composed of monoatomic thick layers of carbon in various shapes. With its high conductivity and a convenient build time of just a few seconds, LIG ​​seems to be the ideal setting for sensing equipment, but there is an important caveat.

“The challenge here is that LIG is not sensitive to glucose at all,” Cheng said. “So we need to deposit a glucose sensitive material in LIG.”

According to Cheng, the team chose nickel because of its strong sensitivity to glucose and combined it with gold to reduce the potential risk of allergic reactions. The researchers hypothesized that LIG equipped with a nickel-gold alloy could detect low concentrations of glucose in sweat on the skin’s surface.

Non-invasive blood glucose monitoring equipment is currently not available in the United States, so diabetics must collect blood samples or use sensors embedded under the skin to measure blood glucose levels. Now, with a new wearable device created by researchers at Penn State University, less invasive glucose monitoring may become the norm.

Materials with high glucose sensitivity are a priority. Compared with blood, the glucose concentration in sweat is very low, but according to Cheng, there is a strong correlation between sweat and blood glucose levels. Although the concentration of glucose in sweat is about 100 times lower than that in blood, the device is sensitive enough to accurately measure glucose in sweat and reflect the concentration in blood.

The sensitivity of the nickel-gold alloy allowed Cheng’s team to rule out enzymes, which are often used to measure glucose in more invasive commercially available devices or non-invasive monitors proposed by other researchers. However, these enzymes degrade rapidly with time and temperature changes.

“Enzyme sensors must be maintained at a certain temperature and pH, and enzymes cannot be stored for a long time,” Cheng said. “On the other hand, regardless of these changes, non-enzymatic glucose sensors are advantageous in terms of stable performance and glucose sensitivity.”

Non-enzymatic sensors require alkaline solutions, which can damage the skin and often limit the usability of the device. To solve this problem, Cheng and his team installed a microfluidic chamber on LIG alloy. The chamber is smaller than previously developed configurations to improve usability and porosity to allow range of motion, such as stretching or squeezing. It is connected to the collection inlet to allow sweat to enter the solution without allowing the solution to touch the skin. The alkaline solution interacts with glucose molecules to produce compounds that react with the alloy. This response triggers an electrical signal that indicates the concentration of glucose in sweat.

Cheng said that with a smaller alkaline solution chamber, the entire device is about a quarter the size and flexible enough to maintain a safe connection with the human body.

In the proof-of-concept, researchers used a skin-safe adhesive to attach a reusable device to a person’s arm one and three hours after a meal. The subjects performed a short exercise before each measurement time, and the exercise time was long enough to produce sweat. Within minutes of collecting sweat, the researchers found that the detected glucose concentration dropped from the first measurement to the next. The device glucose measurement was verified by measurement using a commercially available glucose monitor.

Cheng and team plan to improve their prototype for future applications, including solving how patients or clinicians can use sensors for incremental glucose measurement or continuous monitoring to determine treatment measures, such as insulin delivery. They also intend to refine and expand this platform to more comfortably monitor other biomarkers, which can be found in sweat or interstitial fluid that fills the space between body cells.

“We hope to work with doctors and other healthcare providers to see how we can apply this technology to the daily monitoring of patients,” Cheng said. “This glucose sensor is a good example, showing that we can improve the detection of biomarkers in sweat at very low concentrations.”

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