Currently, diagnosing diabetes and prediabetes means a visit to a doctor's office or lab work, both of which can be expensive and time-consuming. Research from Huanyu "Larry" Cheng at Penn State has yielded a sensor that can help diagnose diabetes and prediabetes on-site in a few minutes with just a breath sample.

Previous diagnostic methods have used glucose found in blood or sweat, but the current sensor  however, this non-invasive test uses a sensor to detect acetone levels in breath. While acetone in breath is a normal byproduct from the burning of fat, an acetone level of 1.8 parts per million is a sign of diabetes.

“While we have sensors that can detect glucose in sweat, these require that we induce sweat through exercise, chemicals or a sauna, which are not always practical or convenient,” Cheng said. “This sensor only requires that you exhale into a bag, dip the sensor in, and wait a few minutes for results.”

While there have been other breath detection methods in the past, they have required lab analysis. Acetone can be detected and read on-site, making the new sensors cost-effective and convenient.

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A team led by a researcher at Penn State has developed a sensor that can help diagnose diabetes and prediabetes on-site in a few minutes using just a breath sample. Courtesy of Penn State University.

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Beyond using acetone as the biomarker, Cheng said another novelty of the sensor came down to design and materials — primarily laser-induced graphene. To create this material, a CO2 laser is used to burn the carbon-containing materials, such as the polyimide film in this work, to create patterned porous graphene with large defects desirable for sensing. 

The porous nature of the graphene helps to let the gas pass through, which means there is a higher likelihood of the acetone molecules being captured. By itself, laser graphene didn’t identify acetone as precisely as needed, which the team remedied by combining the graphene with zinc oxide.

“A junction formed between these two materials that allowed for greater selective detection of acetone as opposed to other molecules,” Cheng said.  

Cheng said another challenge was that the sensor surface could also absorb water molecules, and because breath is humid, the water molecules could compete with the target acetone molecule. To address this, the researchers introduced a selective membrane, or moisture barrier layer, that could block water but allow the acetone to permeate the layer. 

Currently, the method requires that a person breathe directly into a bag to avoid interference from factors such as airflow in the ambient environment. The next step is to improve the sensor so that it can be used directly under the nose or attached to the inside of a mask, since the gas can be detected in the condensation of the exhaled breath. He said he also plans to investigate how an acetone-detecting breath sensor could be used to optimize health initiatives for individuals.  

“If we could better understand how acetone levels in the breath change with diet and exercise, in the same way we see fluctuations in glucose levels depending on when and what a person eats, it would be a very exciting opportunity to use this for health applications beyond diagnosing diabetes,” Cheng said. 

The research was published in Chemical Engineering Journal (www.doi.org/10.1016/j.cej.2025.164857).

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