Researchers Develop Noninvasive Glucose Monitor

Nanoengineers at the UCSD Jacobs School of Engineering recently published a study describing a new, noninvasive method of monitoring glucose levels for patients living with Type 1 diabetes. The study was published in the journal Analytical Chemistry on Dec. 12 and Jacobs School of Engineering announced its success with test subjects on Jan. 14.

The team of researchers was part of a nanobioelectronics laboratory at the

Jacobs School led by Professor Joseph Wang, who is the Science Applications International Corporation-endowed department chair of nanoengineering as well as the director of the Center for Wearable Sensors.

Patients with diabetes typically have to poke a small hole in their fingers and withdraw a few drops of blood several times a day in order to measure if their glucose levels are too high. Graduate student Amay Bandodkar, one of the principal engineers, told the UCSD Guardian that his colleagues wanted to develop a device that avoids puncturing the skin entirely.

“Millions of people all over the globe suffer from diabetes and many of these [people] have to test their blood sugar levels several times a day. This is very inconvenient and painful,” Bandodkar said. “This motivated us to develop a simple rub-on, tattoo-based sensor that can measure blood glucose levels without the need for the painful blood sampling.”

Instead of the traditional method of continuous finger-pricking for blood samples, the team of researchers developed an epidermal tattoo-based technique that measures glucose levels under the skin without perforating it. According to the study, the device then uses the electrodes to attract sodium ions that carry glucose molecules and uses a reacting enzyme to measure the resulting strength of the electric charge produced. This calculates the patient’s overall glucose levels. The sensor only costs a few cents and currently lasts for an entire day, which eliminates the need to manually check blood sugar levels multiple times daily.

Bandodkar explained that the glucose sensor implanted inside the device is crucial when it comes to precisely measuring glucose levels.

“The concentration of glucose extracted by the noninvasive tattoo device is almost 100 times lower than the corresponding level in the human blood,” Bandodkar said in a Jan. 14 Jacobs School of Engineering press release. “Thus, we had to develop a highly sensitive glucose sensor that could detect such low levels of glucose with high selectivity.”

The team tested the tattoo on seven non-diabetic volunteers between the ages of 20 and 40. None of the subjects reported feeling any form of discomfort except for mild tingling within the first 10 seconds of application. This differentiates the device from its predecessor, a product called GlucoWatch, which was released in 2002 by Cygnus Inc. but discontinued due to reports of skin irritation. Wang’s team eliminated this issue by employing a lower amount of electricity during the extraction process.

Ceren Yardimci, a researcher and an associate professor from Hacettepe University in Turkey, told the Guardian that the team is currently working on implementing Bluetooth technology and added that the tattoo could potentially provide information about other conditions in the body.

“Our team is working toward developing wireless devices that would be able to send the information either to the patient’s doctor or to another device,” Yardimci said. “This kind of sensor would be able to detect other chemicals which can give information about other disease[s] or health conditions of patients.”

According to the study, these tattoo-based sensors have already successfully monitored sweat electrolytes and a metabolite called lactate, which can be used to analyze fitness activity. Bandodkar explained that measurements from sweat can also be used to gauge the amount of alcohol present in the bloodstream.

“There is a good correlation between blood alcohol level and alcoholcontentinsweat,” Bandodkar said. “So by measuring alcohol in sweat, one can identify how much alcohol must be there in the blood. This method is more reliable than the breath analyzers.”

He added that detailed analysis of amino acids in the skin’s interstitial fluid, which is the fluid used in the glucosesensor,can be used to detect illegal drugs in the blood.