Researchers have developed a novel sensor capable of detecting stress hormones in human blood and urine with remarkable accuracy. The new technology was developed by an international team of researchers, including those from National Taipei University of Technology, Taiwan; Thiagarajar College, Tamil Nadu; Nanyang Technological University, Singapore, and others. Their new method employs a novel nanohybrid material to track norepinephrine, the neurotransmitter responsible for the fight-or-flight response. The study, published in the journal Bioelectrochemistry, offers a faster and more affordable alternative to traditional medical tests, potentially opening the door for real-time health monitoring. 

The researchers, led by Rajalakshmi Sakthivel from the National Taipei University of Technology, combined two specialised materials to create the sensor: rhenium diselenide and a specific type of bismuth ferrite. Rhenium diselenide is a relatively new member of a family of materials called transition metal dichalcogenides, which are prized in the tech world for being incredibly thin (often only a few atoms thick) and having a large surface area. By decorating these thin nanosheets with bismuth ferrite, a material known for its stable and magnetic properties, the team created a platform that is highly effective at capturing and measuring the electrical signals of hormones.

The device’s operation relies on electrochemistry. When a blood serum or urine sample is applied to the sensor, norepinephrine molecules interact with the nanohybrid surface. This interaction triggers a chemical reaction involving the transfer of two electrons and two protons. Because the new nanohybrid material is such an efficient conductor, it can pick up even tiny electrical changes produced by this reaction. In laboratory tests, the sensor detected hormone levels at extremely low concentrations, with a detection limit of 0.112 micromolar. This level of sensitivity enables physicians to detect even subtle changes in a patient’s stress levels. 

Traditionally, hospitals rely on techniques like chromatography or fluorescence to measure stress hormones. While these methods are very accurate, they are often slow, require expensive laboratory equipment, and involve complex preparation steps that can take hours or even days.

Older electrochemical sensors often struggled with sluggish electron transfer, meaning they weren’t sensitive enough to be reliable. By engineering this specific nanohybrid, the researchers have overcome these hurdles, creating a device that is stable, selective, and effective even in complex biological fluids such as human urine.

However, although the device employs excellent conductors, the team had to determine the optimal thickness of the sensor coating. If the material was applied too thickly to the electrode, it impeded electron flow, reducing the sensor’s effectiveness. They eventually determined that a concentration of 4 milligrams per millilitre provided the optimal balance for high-speed detection.

The ability to monitor norepinephrine is vital because abnormal levels are linked to serious conditions, including heart disease, depression, and neurodegenerative disorders. By providing a stable and reusable platform that can distinguish stress hormones from other common molecules in the body, this research paves the way for portable medical kits. This leap in nanotechnology brings society closer to a future in which advanced medical diagnostics are as simple and accessible as a digital thermometer.