Researchers at KAUST have developed a prototype sensor designed to measure glucose levels in saliva. The team believes that this technology could potentially provide a straightforward, swift, and painless way for individuals to track their diabetes.
Diabetes is a condition that arises when the body struggles to control its blood glucose levels. Elevated glucose levels can contribute to the development of cardiovascular disease and other related health issues. Therefore, it is crucial for individuals with diabetes to effectively manage their blood glucose levels within a moderate range.
Individuals with diabetes have traditionally tracked their blood glucose levels by utilizing devices that analyze a small blood droplet obtained through finger pricking multiple times each day. Recently, implanted sensors have emerged as a viable alternative, offering continuous glucose monitoring without the need for uncomfortable pinpricks. However, these devices can be less accurate for lower glucose levels and are not approved for children.
An easier way to track glucose could be via testing saliva, which is associated with blood glucose levels. However, glucose concentrations are much lower in saliva than in blood, making it challenging to measure precisely without advanced lab equipment.
To help combat this issue, the KAUST team has created a highly sensitive glucose detector that is based on a thin-film transistor. Such tiny, lightweight, and low-power devices could be suitable for mass production as cheap disposable sensors, says team member Abhinav Sharma.
An easy-to-use noninvasive glucose-measuring device using saliva as a medium could be life-changing for millions of patients worldwide.
Abhinav Sharma, King Abdullah University of Science and Technology
The transistor comprises thin layers of the semiconductors zinc oxide and indium oxide, topped with the enzyme glucose oxidase.
When a sample of saliva is placed on the sensor, the specific enzyme oxidizes any glucose present to produce D-gluconolactone and hydrogen peroxide. Electrical oxidation of the hydrogen peroxide then produces electrons that enter the semiconductor layers. That changes the current flowing through the semiconductors, and the size of this effect indicates the glucose concentration within the sample.
The scientists tested their device using human saliva samples that had varied amounts of glucose in them and also examined saliva from volunteers who had fasted before taking the tests (glucose levels in saliva might not associate with blood glucose instantly after a meal).
They identified that the device was able to correctly measure an extensive range of glucose concentrations in just one minute.
Crucially, the sensor was not foiled by other molecules in saliva, including sugar derivatives such as fructose and sucrose. Although the sensitivity of the device declined over time, it still offered good performance after being stored for two weeks at room temperature.
Now, the team is developing a collection of transistor sensors that could concurrently sense several metabolites in saliva. “The development of portable sensor arrays that can be integrated with a smartphone is a potential future direction for research,” states Thomas Anthopoulos, who headed the team.
Sharma, A., et al. Non-invasive, ultrasensitive detection of glucose in saliva using metal oxide transistors. Biosensors and Bioelectronics. doi.org/10.1016/j.bios.2023.115448.